Re: [RBW] Re: Shimmy cured
On Fri, 2013-01-04 at 20:51 -0800, allenmichael wrote: Probably too much to hope for that it will also quiet the front-wheel dive at low speeds going uphill with a front load (which was much better on second tour with less weight placed lower in the front), but i'm still wanting to try it out. What is front wheel dive? Are you perhaps talking about the effect of wheel flop? -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
at all speeds. This is very strange. Can you describe the feeling of the shimmy you experience? Usually shimmy occurs at very distinct speed ranges; for example, I once experienced it on my '95 custom at just under 20 mph. I had ridden the bike for Ks of miles and never had shimmy, until the shimmy showed up for a couple of weeks. After a couple of weeks, it disappeared. The cause could have been something as simple as a slightly different f/r weight distribution or f/r tire pressure, but it was a very particular phenomenon that lasted for only a very short time. On my current '03 Curt road, I've had it occur on a couple of rides at very particular speeds, only to disappear entirely on subsequent rides. Thus, to have shimmy on a bike over a wide range of speeds and for a long period is, to my experience, very odd. Note too that Rivendell bicycles, in my experience (3 customs, one Sam) are not the best for more than minimal (over 5 lb) front loads -- tho' of course, this too depends on how and where the front loads are attached to the bike. My Sam would not keep a straight line with heavy loads in a bar bag or in front low rider panniers. On Sat, Jan 5, 2013 at 12:54 PM, Scot Brooks scothinck...@gmail.com wrote: Great timing for this topic since I've noticed my Sam/Surly Rack/Saddlesack Large combo makes for a bike that has pretty extreme shimmy at nearly all speeds. With the bike stripped I can ride as long as I please no-handed but its a hairy proposition with the rack and bag, even without a load. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/kdGLTkKQLuwJ. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- - Patrick Moore, Albuquerque, NM, USA For professional resumes, contact Patrick Moore, ACRW http://resumespecialties.com/index.html - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
Patrick, In my case all speeds is really all speeds I ride at which is probably between 12mph and 20mph or thereabouts. It happens with and without front load. For instance, my grocery run last weekend was all loaded into my saddlesack, but this weekend I split it up between the saddlesack and the front basket. Same result, same shimmy. It DOESN'T happen at all when I have no racks/bags/baskets on the bike.Having said that, it's not any major inconvenience but I might have a look at the prescribed headset cure before too long. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/46xgRK-E_0MJ. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
Forgot to describe it; it's a back and forth wobble of maybe 4 or 5 inches total side-to-side movement. Maybe more. It doesn't get any more or less pronounced at different speeds that I can tell but the frequency gets a little scary when I'm going quickly. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/PBoDNctCq_8J. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
On Sat, 2013-01-05 at 12:52 -0800, Scot Brooks wrote: Patrick, In my case all speeds is really all speeds I ride at which is probably between 12mph and 20mph or thereabouts. It happens with and without front load. For instance, my grocery run last weekend was all loaded into my saddlesack, but this weekend I split it up between the saddlesack and the front basket. Same result, same shimmy. It DOESN'T happen at all when I have no racks/bags/baskets on the bike.Having said that, it's not any major inconvenience but I might have a look at the prescribed headset cure before too long. I'm with Patrick. That doesn't sound like a classic shimmy at all. I think you may be having issues with your load or your racks. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
When it shimmies at all speeds and doesn't dissipate when touching the top tube it is usually from what I've seen .. a:] Headset (either adjustment or worn out) b:] alignment (check forks If it was when loaded then moving loads etc would usually fix it. My experience with front loads is different than Patricks. My wife's Atlantis and my Bombadil handle 30 to 40 lbs with low riders beautifully ... My quickbeam does well with 5 to 10 lbs even on high speed down hills. We've both been very happy as well with the handling fully loaded going up hill at slow speeds.. slow cadence in 24x36 one handed while drinking coffee on a long climb. My point being there is something wrong that in my opinion can be fixed with some repair in your case if it happens loaded unloaded etc. It's not something to just accept. The only shimmy I would put up with would be a free handed shimmy that goes away instantly when touching the top tube at certain speeds only or when induced. Kelly On Saturday, January 5, 2013 2:57:04 PM UTC-6, Scot Brooks wrote: Forgot to describe it; it's a back and forth wobble of maybe 4 or 5 inches total side-to-side movement. Maybe more. It doesn't get any more or less pronounced at different speeds that I can tell but the frequency gets a little scary when I'm going quickly. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/CWyfGUt4oWUJ. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
My Atlantis handles 50 or 60 pounds, with maybe 25 up front on lowriders, with aplomb. The only time I get shimmy is when putting a lot of weight in my handlebar bag; then I get shimmy on the downhills. It is alleviated at once if I remove a couple of heavy things from the handlebar bag. I use an Ortlieb front handlebar bag with no decaleur. I don't want to use a decaleur, but if I did I'm sure it would remove the shimmy. My experience with front loads is different than Patricks. My wife's Atlantis and my Bombadil handle 30 to 40 lbs with low riders beautifully ... -- -- Anne Paulson My hovercraft is full of eels -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
has anybody tried overtightening their headset to replicate 'roller bearing drag' which seems to cure shimmy? mike goldman warwick,r.i. Woman is 53 But Looks 25 Mom reveals 1 simple wrinkle trick that has angered doctors... http://thirdpartyoffers.juno.com/TGL3131/50e6fa57be7d57a572926st01duc -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy cured
I tried that but then I just got notchiness which was aggravating for the whole trip. On Fri, Jan 4, 2013 at 10:49 AM, mikel66...@juno.com mikel66...@juno.comwrote: has anybody tried overtightening their headset to replicate 'roller bearing drag' which seems to cure shimmy? mike goldman warwick,r.i. *Woman is 53 But Looks 25* Mom reveals 1 simple wrinkle trick that has angered doctors... http://thirdpartyoffers.juno.com/TGL3132/50e6fa57be7d57a572926st01duc ConsumerLifestyleMag.comhttp://thirdpartyoffers.juno.com/TGL3132/50e6fa57be7d57a572926st01duc -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Tue, Dec 21, 2010 at 13:25, William tapebu...@gmail.com wrote: I loaded my 56cm Bombadil with the trunksack small on the Nitto Mini front. I moved the Nitto R-14 rear and the loaded Saddlesack Large over to the Bombadil. The Bombadil does shimmy with that load. But it is at a much higher frequency and a smaller amplitude. The amplitude was almost small enough to just ignore. It also happened at a somewhat higher speed. More notes for the notebook. The R-14 looks to my eye like it would be very flexible. I still think that it is the main culprit here. It would be an interesting experiment to keep everything the same but have the bag on a stiffer rack. James Black Los Angeles, CA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Tue, 2010-12-21 at 14:29 -0800, William wrote: Nobody conclusively says that such things are causes or enablers of shimmy, or will bet their life on removing such loads being a cure to shimmy They'd be very foolish to do so, since there are many things that can cause shimmy including rider behavior. Another near-term experiment will be to load the same Saddlesack large to a much stiffer rear rack. The Hillborne now has the rack that came with my Burley Piccolo. It's a beast. Fat cro-mo tubes welded, bomber. If the shimmy comes from rear load floppiness, and if the critical flopiness comes from the rack, then that Burley rack should change the shimmy properties substantially. If the critical flopiness comes from the Saddlesack large, then the rack won't change anything. I hope you solve your problem, but when you've done it you still won't be able to make any kind of sweeping, definitive statement about what causes and what cures shimmy. At most you'll be able to say I did this to cure mine. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
I've got a 56 Sam that I ran a R-14 on with 2 Ortliebs fairly well loaded, or (alternatively) a Big Loafer on top... nary a shimmy (with a mini+loaf on the front). ymmv, of course, but i never noticed any flexiness from the R-14. -a On Dec 21, 2010, at 8:08 PM, doug peterson wrote: Just looked up the R-14 on Riv's site: 13 lbs capacity. It's surprising how quickly weight can add up. The R-14 is an elegant looking rack but with just the support struts for stability it may lack lateral stiffness. dougP On Dec 21, 2:20 pm, james black chocot...@gmail.com wrote: On Tue, Dec 21, 2010 at 13:25, William tapebu...@gmail.com wrote: I loaded my 56cm Bombadil with the trunksack small on the Nitto Mini front. I moved the Nitto R-14 rear and the loaded Saddlesack Large over to the Bombadil. The Bombadil does shimmy with that load. But it is at a much higher frequency and a smaller amplitude. The amplitude was almost small enough to just ignore. It also happened at a somewhat higher speed. More notes for the notebook. The R-14 looks to my eye like it would be very flexible. I still think that it is the main culprit here. It would be an interesting experiment to keep everything the same but have the bag on a stiffer rack. James Black Los Angeles, CA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
I was thinking that the factor is the weight of the rear bag, not the rack. Can you verify if without the rack but with the bag anything changes? My Atlantis with the same rack-bag combo + Noodle bars and shimmies. When I put the Albatross bars it didn't shimmy but I couldn't get used to them. Now I'm putting the Noodles back on and will see what happens. Running 50mm Marathon Supremes. Rene Sent from my iPhone 4 On Dec 21, 2010, at 3:27 PM, Michael_S mikeybi...@rocketmail.com wrote: I was thinking another variable may be wheels. Have you tried swapping wheels from another bike to see if that changes or helps anything? Or tire switching as well? both seem like easy changes to make. Rotating components can certainly affect the dynamic response of the bike. Other things like frame alignment, new headsets and such are more costly to do. Keep trying.. ~Mike~ On Dec 21, 2:37 pm, Steve Palincsar palin...@his.com wrote: On Tue, 2010-12-21 at 14:29 -0800, William wrote: Nobody conclusively says that such things are causes or enablers of shimmy, or will bet their life on removing such loads being a cure to shimmy They'd be very foolish to do so, since there are many things that can cause shimmy including rider behavior. Another near-term experiment will be to load the same Saddlesack large to a much stiffer rear rack. The Hillborne now has the rack that came with my Burley Piccolo. It's a beast. Fat cro-mo tubes welded, bomber. If the shimmy comes from rear load floppiness, and if the critical flopiness comes from the rack, then that Burley rack should change the shimmy properties substantially. If the critical flopiness comes from the Saddlesack large, then the rack won't change anything. I hope you solve your problem, but when you've done it you still won't be able to make any kind of sweeping, definitive statement about what causes and what cures shimmy. At most you'll be able to say I did this to cure mine. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ NRC
I did in fact, mean 26 frame w/ 27 wheels. Sent from my Verizon Wireless BlackBerry -Original Message- From: Bill M. bmenn...@comcast.net Sender: rbw-owners-bunch@googlegroups.com Date: Sun, 12 Dec 2010 22:22:52 To: RBW Owners Bunchrbw-owners-bunch@googlegroups.com Reply-To: rbw-owners-bunch@googlegroups.com Subject: [RBW] Re: Shimmy, according to BQ NRC You sure he didn't mean a 26 frame size (not wheel size)? On Dec 12, 11:42 am, Steve Palincsar palin...@his.com wrote: On Sun, 2010-12-12 at 14:40 -0500, Robert Zeidler wrote: I concur with your opinion on the Paramount. I, too, have a few of the 26 bikes, all 531 , and find they are rock steady. Is this a 27 wheel thing maybe? I do not recall a 1972 Paramount coming with 26 wheels. FWIW, mine had 27. The other option was tubulars. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Mon, Dec 13, 2010 at 16:13, William tapebu...@gmail.com wrote: The fundamental conclusion I can make already is that front end shimmy at moderate speed no-handed is not a fundamental property of this bicycle. What kind of rear rack do you have? Based on your account, I'm guessing that an overly flexible rear rack is contributing to the shimmy problem on your bike. I really wouldn't expect a bike with the geometry and stout tubing of the Sam Hillborne to shimmy under less than extreme loading, and was surprised to read your account when you first brought it up. James Black Los Angeles, CA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Mon, Dec 13, 2010 at 7:13 PM, William tapebu...@gmail.com wrote: The fundamental conclusion I can make already is that front end shimmy at moderate speed no-handed is not a fundamental property of this bicycle. It's a property of a particular configuration on this bicycle. If I don't like it, I can configure this bike differently. If I choose to configure my bike this way, I should be prepared to accept some shimmy. Jan's article encouraged me to experiment, and I've started doing that, and I'm learning more about my bike, and that's all good stuff. How much do you weigh + yourstuff? How Are the bars set up vis-a-vis the saddle? -sv -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ NRC
It would interesting to know what combination of factors are attributable to a bike having a tendency for speed wobbles. Jim Cloud Tucson, AZ Which is the subject of the Shimmy Review in the Winter BQ! The Winter BQ recounts opinions and experiences from the past 100 years in a few pages, and points toward ways to reduce or eliminate the phenomenon. Subscribe, and you will not regret it! Well, I don't know that, but I haven't regretted it. I went ahead and got the whole set. If you do, too, you'll see how groups of riders, some of whom have considerable training in science, have been exploring French bicycles, yes, but also other than French bicycles, discovering and introducing a rich body of cycling knowledge that never made it to the mass market in the USA, but which was extremely influential, and promises further progress as we develop new materials and, I hope, a new society as we rebuild American cities and a better way of life...But, that is just my fond fantasy... -- Bill Gibson Tempe, Arizona, USA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ NRC
I concur with your opinion on the Paramount. I, too, have a few of the 26 bikes, all 531 , and find they are rock steady. Is this a 27 wheel thing maybe? Sent from my iPad On Dec 12, 2010, at 12:43 PM, Jim Cloud cloud...@aol.com wrote: Your experience with a 1972 Paramount is interesting. I have a 1977 P-15 Paramount, that I'm still riding, and I've never experienced any problems with speed wobbles. It's a 26 frame bike with a 110mm extension on the stem. It's rock steady descending on steep roads with speeds attained of 45-55mph.. The only bike, that I've ridden, that exhibited a tendency toward speed wobbles was a 63 cm Pogliaghi Italcorse bike I purchased in 1974. It would occasionally develop a speed wobble riding on a level road, that I could dampen fairly easily by pressing one knee against the top tube. For some reason, it never developed a speed wobble while descending (and this was while I lived in Boulder, CO where there were many opportunities for fast descents!). It would interesting to know what combination of factors are attributable to a bike having a tendency for speed wobbles. Jim Cloud Tucson, AZ On Dec 12, 10:08 am, Steve Palincsar palin...@his.com wrote: On Sat, 2010-12-11 at 20:18 -0800, james black wrote: On Sat, Dec 11, 2010 at 04:59, Steve Palincsar palin...@his.com wrote: Knee to top tube is a highly effective and well known (in my experience) way to stop /speed wobble/ -- as distinguished from shimmy. And speed wobble happens with hands on the bars, in fact can be caused by those hands on the bar (death grip or shivering). In discussions about shimmy (of which there have been many over the years on this and other lists) I have often described a distinction between what I call speed wobble and what I call shimmy. Knee to top tube is effective on shimmy (meaning the oscillation one encounters riding no hands at normal cruising speeds of 15-20 mph), but it's hard to put a knee to top tube while pedaling, so this is of limited application (especially on a fixed gear bike). My 1972 P-15 Paramount had a terrifying speed wobble back when it was new. Clamping the top tube between my knees and trying my best to squeeze the bejeezus out of the tube did in fact stop the shaking. I subsequently changed the stem length and the speed wobble permanently stopped. The bike always felt marginally unstable on fast descents, though -- I used to describe it as holding my life in a little goldfish bowl by the fingertips, arms outstretched. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ NRC
On Sun, 2010-12-12 at 14:40 -0500, Robert Zeidler wrote: I concur with your opinion on the Paramount. I, too, have a few of the 26 bikes, all 531 , and find they are rock steady. Is this a 27 wheel thing maybe? I do not recall a 1972 Paramount coming with 26 wheels. FWIW, mine had 27. The other option was tubulars. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Fri, 2010-12-10 at 10:29 -0800, Jan Heine wrote: I am beginning to believe that all bikes have a tendency to shimmy, and depending on a number of factors, the oscillations either are dampened or self-reinforce. Which is exactly what Jobst Brandt says in the rec.bicycles.tech FAQ. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
On Fri, 2010-12-10 at 11:04 -0800, newenglandbike wrote: OK, hoping not to spoil for folks who haven't seen the article yet- I thought it was a decent survey of plausible causes for shimmy.It didn't reveal a catch-all cure for the problem, but that's probably b/ c none could possibly exist, since there are so many possible causes, some of them combining with each other.BTW if you're going to try the needle-bearing route, I think velo orange has them now(?) whereas they were getting scarce before. Anyway good luck with sorting out the on your rivendell. The VO 1 threaded roller bearing headset is in fact in stock right now, $36. http://store.velo-orange.com/index.php/components/headsets/vo-roller-bearing-headset-1-threaded.html -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
At last, a voice of reason! In a message dated 12/10/2010 4:21:39 P.M. Eastern Standard Time, montclairbob...@gmail.com writes: With some exceptions (like life-threatening high-speed wobs, no thanks)... maybe it's time we just embrace the shimmy... it could just be our bikes telling us: Slow the F down... Put your damn hands back on the bars Get a trailer if you wanna haul sh** Turn off that awful music on your iPod, it's giving me the shimmies Get me some decent tires and a nice headset, you cheapskate Don't worry about it... It's what makes me ride so nicely at all other times I fully expect to discover a shimmy in my Bomba (at some point)... I'll try not to freak out... Happy Friday, everyone... I'm ready to shimmy myself... Peace, BB On Dec 10, 3:12 pm, William tapebu...@gmail.com wrote: Mike This is part of the voodoo feel to the whole thing. You can find an article that says knobbies damp out shimmy. You can find another that says knobbies supply the excitation force for shimmy. You can find another article that states that wide tires like knobbies are typically more compliant and therefore enable low frequency oscillations to be amplified by the system. My first few experiments are going to be: 1. Baseline the bike. Log initial condition of all independent variables that I might change. Attempt to measure the frequency and amplitude of the shimmy 2. Vary front tire pressure and ride. Note changes 3. Vary rear tire pressure and ride. Note changes 4. take reference weight (like maybe two full water bottles) and put them at various locations on the system and note any changes A. On front rack B. In H2O cages C. In jersey pocket D. On rear rack E. maybe elsewhere 5. Change tires 6. Change front wheel 7. Change rear wheel 8. Tighten headset or similarly damp steering 9. Load rear end heavily 10. Load front end heavily On Dec 10, 11:44 am, Michael_S mikeybi...@rocketmail.com wrote: Funny, Bill, that you say your Hillborne shimmied. The one I had (now sold) was the most stable bike I've ever ridden with no hands in my life. I could have had a 3 course dinner while riding and not even think about touching the bars. I had the standard Riv supplied Tange headset and even with Schwalbe Smart Sams ( a knobbie tire) it was smooth as glass. The replacement bike, a used Ram, is not as stable, but is more like other bikes I've had. Neither bike has any shimmy at all. I did own, for a while, a Cotic Roadrat , but that baby was shimmy city and was sold quickly. On that bike a headset change quieted it as did a tire switch. But I could not get rid of it. I even think the size and shape of the rider could influence it dynamically as much as bike geometry and even things like tire tread pattern. As others have mentioned above, shimmy is a complex set of factors, and due to system (bike/rider) to system variation it can affect one of identical bikes and not the other. ~Mike~ On Dec 10, 11:18 am, William tapebu...@gmail.com wrote: Allan, thanks for that suggestion. On Dec 10, 11:10 am, Allan in Portland allan_f...@aracnet.com wrote: BTW, there's the Bicycle Quarterly Reader's Review list,http://groups.google.com/group/bqrr, that was created as a venue for precisely these types of discussions. Not saying you can't discuss the mag anywhere you please, just saying we'd really appreciate the discussion there. :-) Carry on, -Allan- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy, according to BQ
wish I had my BQ already. On Fri, Dec 10, 2010 at 2:11 PM, bpus...@aol.com wrote: At last, a voice of reason! In a message dated 12/10/2010 4:21:39 P.M. Eastern Standard Time, montclairbob...@gmail.com writes: With some exceptions (like life-threatening high-speed wobs, no thanks)... maybe it's time we just embrace the shimmy... it could just be our bikes telling us: Slow the F down... Put your damn hands back on the bars Get a trailer if you wanna haul sh** Turn off that awful music on your iPod, it's giving me the shimmies Get me some decent tires and a nice headset, you cheapskate Don't worry about it... It's what makes me ride so nicely at all other times I fully expect to discover a shimmy in my Bomba (at some point)... I'll try not to freak out... Happy Friday, everyone... I'm ready to shimmy myself... Peace, BB On Dec 10, 3:12 pm, William tapebu...@gmail.com wrote: Mike This is part of the voodoo feel to the whole thing. You can find an article that says knobbies damp out shimmy. You can find another that says knobbies supply the excitation force for shimmy. You can find another article that states that wide tires like knobbies are typically more compliant and therefore enable low frequency oscillations to be amplified by the system. My first few experiments are going to be: 1. Baseline the bike. Log initial condition of all independent variables that I might change. Attempt to measure the frequency and amplitude of the shimmy 2. Vary front tire pressure and ride. Note changes 3. Vary rear tire pressure and ride. Note changes 4. take reference weight (like maybe two full water bottles) and put them at various locations on the system and note any changes A. On front rack B. In H2O cages C. In jersey pocket D. On rear rack E. maybe elsewhere 5. Change tires 6. Change front wheel 7. Change rear wheel 8. Tighten headset or similarly damp steering 9. Load rear end heavily 10. Load front end heavily On Dec 10, 11:44 am, Michael_S mikeybi...@rocketmail.com wrote: Funny, Bill, that you say your Hillborne shimmied. The one I had (now sold) was the most stable bike I've ever ridden with no hands in my life. I could have had a 3 course dinner while riding and not even think about touching the bars. I had the standard Riv supplied Tange headset and even with Schwalbe Smart Sams ( a knobbie tire) it was smooth as glass. The replacement bike, a used Ram, is not as stable, but is more like other bikes I've had. Neither bike has any shimmy at all. I did own, for a while, a Cotic Roadrat , but that baby was shimmy city and was sold quickly. On that bike a headset change quieted it as did a tire switch. But I could not get rid of it. I even think the size and shape of the rider could influence it dynamically as much as bike geometry and even things like tire tread pattern. As others have mentioned above, shimmy is a complex set of factors, and due to system (bike/rider) to system variation it can affect one of identical bikes and not the other. ~Mike~ On Dec 10, 11:18 am, William tapebu...@gmail.com wrote: Allan, thanks for that suggestion. On Dec 10, 11:10 am, Allan in Portland allan_f...@aracnet.com wrote: BTW, there's the Bicycle Quarterly Reader's Review list, http://groups.google.com/group/bqrr, that was created as a venue for precisely these types of discussions. Not saying you can't discuss the mag anywhere you please, just saying we'd really appreciate the discussion there. :-) Carry on, -Allan- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.comrbw-owners-bunch%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.comrbw-owners-bunch%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at
Re: [RBW] Re: Shimmy!
Here's why I made my assumption: i tense up and apply the brakes a little. I sit down reflexively to lower my center of gravity, which we all do when it looks like we are going to fall. To not do this requires extraordinary will power and confidence. Instantly, your Quickbeam starts to shake violently. My arms go stiff, and I grip the brakes harder to make it stop, but of course all this makes it shake harder. I'm sure you meant what you just wrote, but the initial post clearly alluded to tensing up and braking. Thanks for the added clarificatioms and detailed explanations from everyone. René On Monday, August 9, 2010, MichaelH mhech...@gmail.com wrote: Actually, I said no such thing. I wrote that I was going 45 mph and moved from the drops to the tops a tuck when the slight vibration started. I immediately reverted to the drops the vibration stopped. Thanks for the reference to the ibob, discusiion Brandt's thoughts. The thing that most struck me was Jobst assertion that shimmy should be repeatable event, so I set out today, the last day of my vacation, to climb the same mountain road with exactly the same set up and see if I could repeat the shimmy on the descent. Unfortunately I got rained out before I could complete this exercise. I did take a much hillier route over the the base of the mountain to see if I could reproduce it at somewhat slower speeds. When Prof. Garmin recorded my speed at 37.5, I let go of the handlebars on my Rambouillet. Then I shifted my weight between the pedals and seat, but was unable to create any shimmy. The road was relatively smooth, like the downhill that originally created a vibration, but it did have a long series of vertical tar snakes running across the road. I repeated this exercise on a bumpy road at 31 mph, and again, nothing. I headed up the mountain road, but only got about one mile when the skies opened; so I spent a pleasant half hour in a barn with a farm worker overhauling a tractor engine. We hit it off despite the fact that his english wasn't any better than my spanish. After thatI decided it wasn't a good day for high balling down the mountain. Michael On Aug 9, 6:28 pm, Rene Sterental orthie...@gmail.com wrote: y confusion. It's just that the OP stated that at speed he'd see a bump or something, would tense and hit the brakes and the vibrations would start; it threw me off. René -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
on 8/10/10 4:38 AM, Rene Sterental at orthie...@gmail.com wrote: Here's why I made my assumption: i tense up and apply the brakes a little... (snipped) That was a follow up post made by Bob C. Not the original post. Further, I'm not quite sure why this was referenced to Angus' Quickbeam, other than a this could happen to you... example. If I followed Bob's post appropriately, he was saying _all_ bicycles exhibited shimmy, when he rode them. This gets back to the variability of the rider's mass and position, etc., rather than anything intrinsic to Riv/GP designs. - J -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
Thanks for setting me straight again! :-) I obviously missed the beginning of the thread. My apologies to the OP... :-) René On 8/10/10, CycloFiend cyclofi...@earthlink.net wrote: on 8/10/10 4:38 AM, Rene Sterental at orthie...@gmail.com wrote: Here's why I made my assumption: i tense up and apply the brakes a little... (snipped) That was a follow up post made by Bob C. Not the original post. Further, I'm not quite sure why this was referenced to Angus' Quickbeam, other than a this could happen to you... example. If I followed Bob's post appropriately, he was saying _all_ bicycles exhibited shimmy, when he rode them. This gets back to the variability of the rider's mass and position, etc., rather than anything intrinsic to Riv/GP designs. - J -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- Sent from my mobile device -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
on 8/8/10 4:12 AM, MichaelH at mhech...@gmail.com wrote: Lots of interesting thoughts and suggestions here. I haven't heard from anyone who thinks the very narrow tires might have contributed to it. Tires can definitely be a factor. Ride buddy JimG had consistent shimmy issues on his Kog P/R 700C and reduced them by (among other things) using larger tires. He'd posted about them over on the iBob list and blogged about them as well. http://sfcyclotouring.blogspot.com/search?q=shimmy - Jim -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
on 8/8/10 12:21 PM, MichaelH at mhech...@gmail.com wrote: Up till yesterday the Rambouillet has had impeccable road manners. I don't think I would buy a second bike from someone who had sold me a frame with built in shimmy. True shimmy is a reproduceable event. There is typically a specific speed that it starts at - not necessarily fast. It also has a lot of variables, and it doesn't seem like anyone has ever actually nailed them down. Jobst, Sheldon, etc... a little more forward weight, a little less tire pressure, slightly tighter headset all change things, it appears. It sounds like the event could have been more of a wobble - maybe caused by specific circumstances than intrinsic behavior. I've had that happen once and have never been able to reproduce it. (wet road descent, heavily rear loaded, uneven but smooth road surface, who-knows-what-else...) - J -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes Gallery updates now appear here - http://cyclofiend.blogspot.com Then I sat up, wiped the water out of my eyes, and looked at my bike, and just like that I knew it was dead -- Robert McCammon, Boy's Life -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
Does this only happen when you brake and goes away if you stop braking? Does I happen in bikes with canti brakes but not on bikes with sidepull brakes? I've had this problem only on a Gunnar with canti brakes. Have yet to descend fast on the Atlantis to see if it will happen. Front cantilever brakes when applied hard at high speeds produce this effect due to fork flex and forces applied when braking as the fork flexes and extends back repeatedly (my crude explanation). The first time this happened to me on a long fast descent it scared me badly as I thought the fork was broken (carbon). This doesn't seem to happen with sidepulls as they are bolted where there is no fork flex. I'm pretty sure brake type, leverage, pads, rim quality are some additional variables that play a role here. A highly modulating brake setup should help. There was very little modulation on the Gunnar setup compared to how I've now learned to set up high profile cantis after doing some research. René On 8/9/10, Bob Cooper robertcoo...@frontiernet.net wrote: Hello Angus, et al, The scenario is this: I’m riding Angus’ Quickbeam down Italy Turnpike outside Naples, New York. Your Quickbeam has just been serviced by a great mechanic. The frame is straight; the wheels are perfect; the tires are perfect; this headset is perfect. By coincidence, the fit is perfect. I have my spare tube and a set of allen wrenches in a little bag under my saddle. It’s a cold, sunny spring morning, and I’m shivering slightly. The fast guys are pulling away from me at 53 mph. I hit a bump in the road hidden by a shadow from a tree. I tense up and apply the brakes a little. I sit down reflexively to lower my center of gravity, which we all do when it looks like we are going to fall. To not do this requires extraordinary will power and confidence. Instantly, your Quickbeam starts to shake violently. My arms go stiff, and I grip the brakes harder to make it stop, but of course all this makes it shake harder. No one has been able to satisfactorily explain this phenomenon. Many have tried; all have failed. I watched the video that Jim G made of his bike shimmy. I couldn’t make a video of this on a big descent, because I can’t do anything when it starts. It’s progressive. It’s violent. It’s profoundly frightening. My 55 cm Raleigh with oversize aluminum tubing does this. My 59 cm Peugeot PX-10 with one-inch top tube does this. All bikes do this, when I am the rider. All of my bikes do this at almost any speed, even 15 mph, but the story ends differently at lower speeds, because I’m not frightened out of my wits at 15 mph. To stay relaxed on a bike that going fast and going out of control is very difficult. When the gradient ahead is INCREASING, it’s even more difficult. Experience, skill, confidence, will power. Sometimes I have these at my disposal, sometimes not. Regards, Bob Cooper -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- Sent from my mobile device -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
On Mon, 2010-08-09 at 08:44 -0700, Bob Cooper wrote: It’s a cold, sunny spring morning, and I’m shivering slightly. That right there is enough to initiate a shimmy. I hit a bump in the road hidden by a shadow from a tree. I tense up And per the FAQ that itself is a contributing factor in shimmy. and apply the brakes a little. I sit down reflexively to lower my center of gravity, which we all do when it looks like we are going to fall. To not do this requires extraordinary will power and confidence. Instantly, your Quickbeam starts to shake violently. My arms go stiff, and I grip the brakes harder to make it stop, but of course all this makes it shake harder. Quoting from the FAQ: Shimmy that concerns riders the most occurs with hands firmly on the bars and it is rider generated by muscular effect whose natural response is the same as the shimmy frequency, about that of Human shivering. Descending in cold weather can be difficult for this reason. The rider's death grip only enhances the incidence of shimmy in this situation. Loosely holding the bars between thumb and forefinger is a way of avoiding shimmy when cold. -- http://www.faqs.org/faqs/bicycles-faq/part4/section-25.html Plenty more good info about this phenomenon at the above URL. No one has been able to satisfactorily explain this phenomenon. Many have tried; all have failed. On the contrary, although some aspects are a bit mysterious the FAQ has lots of successful explanation. I watched the video that Jim G made of his bike shimmy. I couldn’t make a video of this on a big descent, because I can’t do anything when it starts. It’s progressive. It’s violent. It’s profoundly frightening. Your description fits classic speed wobble perfectly. If so, it's NOT what JimG had. That's the other kind of shimmy. And by the way, I agree, there's little in life that's more frightening than speed wobble. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
On Mon, Aug 9, 2010 at 10:32, Bob Cooper robertcoo...@frontiernet.net wrote: Jobst is the only person who has shed enough light on this problem of mine that, when I actually apply his advise, it has an effect. All praise to Jobst for that post to the FAQ all those years ago. http://sheldonbrown.com/brandt/shimmy.html We have discussed shimmy at much length over on the iBOB list. My opinion is that there is a distinction between what I term speed wobble, which is what you get coasting down a hill at very high speeds, and shimmy, which is what you get when you ride along at 16 mph no-hands. In terms of physics, they might be the same phenomenon, but it seems like bikes are often prone to one or the other, so I think there is good basis for the distinction. I think low-trail bikes are more prone to shimmy, and high-trail bikes relatively more prone to speed wobble. I would expect Rivendells to be more prone to speed wobble - the high trail geometries that started to supplant lower trail geometries a few decades ago seem to have been motivated in part by a desire to eliminate garden-variety shimmy. Pretty much all my bikes exhibit shimmy under some circumstances, and most of my road bikes can shimmy if I ride along no-hands, even when coasting. It's hard to imagine that it's something I am doing as a rider if I am not even pedaling. My low-trail bikes all shimmy riding no-hands, particularly when loaded. Flexible racks contribute to this phenomenon. My mid-trail Centurion hasn't shimmied, but I also don't have any racks on it. I did find recently a slight speed wobble while coasting down a steep hill, though. My 20-wheeled Swift Folder is the only bike I have that has never shimmied, but it's a fixed gear, so I have never tried going 40 mph down a hill on it. My 20-wheeled cargo bike shimmies ferociously, so I know it's not the wheel size, but the frame flex characteristics. I think Jobst's description is lacking, because it only addresses the speed wobble aspect, and not the shimmy aspect of this phenomenon. James Black -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
On Mon, 2010-08-09 at 17:28 -0500, Rene Sterental wrote: You're correct. My confusion. It's just that the OP stated that at speed he'd see a bump or something, would tense and hit the brakes and the vibrations would start; it threw me off. This is quite an interesting discussion but seeing as there is no cure and it's just another bike trait to understand, I'd like to know what is the best way to address it when it happens at high speed on a downhill. That's when things get scary. The low speed wobble is not a real safety concern. Clamp the top tube between your knees. According to the FAQ, a light touch is sufficient; the times it happened to me, I squeezed the bejeezus out of it, trying my best to squash the tube flat - and that worked fine. And then, somehow, without knowing what I did, I changed the setup on the bike and it never did it again. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
I guess that's the best way to get rid of it! :-) Thanks for the emergency solution! René -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Shimmy!
On Sun, 2010-08-08 at 15:31 -0700, Bob Cooper wrote: If I have ten bikes and they all shimmy, and Rider X has ten bikes and none of them shimmy, I think this points in this direction: It’s the rider, not the bike. Certainly, rider actions can initiate or exacerbate a bike's tendency to shimmy. I believe Jobst's FAQ discusses this. However, if some characteristic as a side effect makes a bike more likely to shimmy and the rider selects for the presence of that characteristic, that could explain this as well. How else can it be explained? If a badly loaded handlebar bag caused it, and the rider transferred that badly loaded bag from bike to bike, that could also explain it. If certain sizes were more likely than others to do it, and this rider happened to need that particular size, that might explain it as well. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
