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On Dec 31, 2010, at 8:56 AM, PATRICK MOORE wrote: > 31? 41? Where is coffee .... > > What number am I thinking of? > > On Fri, Dec 31, 2010 at 9:49 AM, doug peterson <[email protected]> wrote: >> Got it; many thanks. >> >> Patrick, RR31 is 7 years old. We're up in the 40s now. >> >> dougP >> >> On Dec 31, 8:25 am, David Faller <[email protected]> wrote: >>> Drink a little more coffee, Patrick... >>> >>> On 12/31/2010 8:15 AM, PATRICK MOORE wrote: >>> >>> >>> >>>> So RR 31 is out -- great, must buy it. Good article. Whatever G's take >>>> on trail, he's built me three excellently handling bikes. >>> >>>> On Thu, Dec 30, 2010 at 9:50 PM, Bill Gibson<[email protected]> >>>> wrote: >>>>> Did you know the pdf author was Milhouse Vanhouten? Cali is a mythical >>>>> place, you know...I have it, but I bought the pdfs from Rivendell...I >>>>> hesitate to violate copyright , but I will quote, assuming you are a loyal >>>>> customer..."Experiments With Rake& Trail" >>>>> Fork rake is how much the front wheel is offset from >>>>> the steering axis a straight line through the center of >>>>> the head tube. The aspect of the bike s steering geometry >>>>> that s affected by fork rake is called trail. Don t confuse >>>>> it with a trail you ride on. >>>>> Road bikes typically have between 2-inches (50.6mm) >>>>> and 2 1/2-inches (63.5mm) of trail, and bike journalists >>>>> who ve written about trail have said 2 1/4-inches >>>>> (57/58mm) of trail makes a bike not too quick, not too >>>>> slow, just right. >>>>> Trail theory says that more trail makes a bike easier to >>>>> control at high speeds and over rough ground. >>>>> Mountain bikes typically have between 2 3/4-inches >>>>> (69.8mm) and three inches 76.2mm) of trail. >>>>> Less trail, according to theory, makes a bike easier to >>>>> control at slow speeds, but harder to control when >>>>> you re going fast, hitting bumps, or both. >>>>> Trail is affected by: (1) the wheel radius; (2) the head >>>>> tube angle; and (3) the fork rake (offset).There are three >>>>> ways to increase trail: >>>>> Bigger front wheel. >>>>> Shallower head tube angle. >>>>> Less fork rake. Most folks who start thinking about >>>>> trail temporarily get confused at least three times, and >>>>> think more rake makes more trail. Nupe. >>>>> To calculate trail using arithmetic: >>>>> Trail = Wheel radius/Tan. of head tube angle minus >>>>> fork offset/Sin. of head tube angle. >>>>> If that s Greek to you, we should be in the same club. I >>>>> have it programmed on my computer here, so I just >>>>> plug in the numbers and there you go >>> >>>>> How Trail Affects Our Frame Designs >>>>> When I design a Rivendell, I find the typical tire the rider >>>>> will ride, and then the biggest. For all-purpose road riding, >>>>> I shoot for 60-61mm of trail with the most common >>>>> tire. That s more than what experts have said results in >>>>> neutral handling, but they are not the boss of me. Nor >>>>> should they be of you! >>>>> Then I see what the trail is with the largest tire. Normally >>>>> a customer will say, I ll ride a 700x28 most of the time, >>>>> but there are some fire roads here, >>>>> and I ll ride 700x35s when I go >>>>> there. Well, that works out just >>>>> fine, because the bigger tire will >>>>> increase the trail, making the bike >>>>> better for the fire road (so goes trail >>>>> theory). >>>>> Most frame designers have a trail >>>>> figure they re comfortable with, >>>>> depending on the bike s intended >>>>> purpose. But some copy other manufacturer s >>>>> geometries not a bad >>>>> thing to do, and I hope we haven t >>>>> reached the point where somebody >>>>> out there considers Xmm of trail to >>>>> be intellectual property. Finally, >>>>> some builders just know from experience >>>>> what works, and don t think about trail. That s >>>>> fine, too! >>>>> In Italy in the 80s it was common for the top makers to >>>>> put 45mm of rake on each fork, regardless of the >>>>> frame s head tube angle. The big bikes, which almost >>>>> always had steeper head tubes, didn t have much trail, >>>>> but the little bikes (with slacker head tubes) had more >>>>> than plenty. I wouldn t say that s all that fine; in fact it >>>>> seems odd to me. But these same Italian frames were >>>>> ridden to many prestigious victories, which will impress >>>>> those in the results speak for themselves camp. I m in >>>>> the trail doesn t win races camp. >>>>> When you first learn about trail, you may find yourself >>>>> getting obsessed. It happened to me and I ve seen it happen >>>>> to others. Trail is interesting, but it is not the sole >>>>> splainer of bike handling, something nobody knows better >>>>> than Waterford s Marc Muller (more on him later). >>>>> The Educational-Type Fun Begins >>>>> FOR ABOUT SEVEN YEARS I VE WANTED to experiment with trail >>>>> by getting some forks with adjustable rakes, so we did. >>>>> We also got non-adjustable forks with no rake, and with >>>>> 65mm (whopping lot) of rake. You can do that when you >>>>> have your own bike company and a publication to get >>>>> out, but it takes more than snapping your fingers. >>>>> The bikes are 59cm Romuluses. The Romulus is a road >>>>> bike with what I think is a perfect geometry for allaround >>>>> road riding. Pertinent to this story, it has a 73- >>>>> degree head tube with 42.5mm of rake, which, with the >>>>> stock Ruffy-Tuffy tire (343mm radius), results in 60mm >>>>> of trail. It is as familiar to me as it gets. >>>>> We equipped three bikes with different forks adjustable >>>>> rake, 0mm rake, and 65mm rake; and of course we have >>>>> a normal one, too (42.5mm rake), so really, four. I rode >>>>> it up and down Mount Diablo and the local streets and >>>>> roads. I rode it loaded and unloaded, on smooth and >>>>> rough ground, holding onto the >>>>> bars like you re supposed to, and >>>>> no hands; over speed bumps (with >>>>> hands and no hands), with a heavy >>>>> basket, and at different speeds. >>>>> The Problem With This Test >>>>> It combines objective numbers and >>>>> subjective feelings, and what I feel >>>>> may not be what you d feel, because >>>>> maybe we re used to different >>>>> bikes, or one of us is more sensitive >>>>> than the other. Also keep in mind >>>>> that describing bicycle handling >>>>> with normal language isn t always >>>>> satisfactory. What I call quick >>>>> might not feel so quick to somebody >>>>> who s used to a 1987 64cm Ciocc (rhymes with >>>>> poach ) Italian racing bike, for instance. >>>>> Then this: I headed into this test knowing it would make >>>>> a Reader story, and I found myself looking harder for >>>>> things that I might not notice normally. I went out hoping >>>>> to find hugely noticeable differences, and any >>>>> nuance of the bike that suggested that got pounced on >>>>> promptly and may be overplayed. I m not saying I couldn t >>>>> tell a difference, I m just saying there s a natural tendency >>>>> to overstate the differences for the sake of a good >>>>> story, even when I m aware of that phenomenon. >>>>> But After All That, Here s What I Think >>>>> I could get used to any bike here. Off the bat I d say I d >>>>> have a harder time getting used to a bike with too much >>>>> trail than I would to a bike with too little, but bikes are >>>>> fun to ride no matter what, so I d get over it. >>>>> Also, I suspect the differences in the extreme versions >>>>> tend to get neutralized when you re on the bike manhandling >>>>> it. I think this because the biggest difference >>>>> came out in no-hands riding the low-trail bikes were >>>>> easy to ride at slow speed, where the tons-o -trail bikes >>>>> were hard; and at high speeds it was just the opposite. >>>>> But at slow or high speed, as long as I had my hands on >>>>> the bars, it didn t seem difficult either way. >>>>> As a bike designer, I find that quite comforting, but I still >>>>> work hard to thread the needle. (Go to the next page now.)... >>> >>>>> There's lot's more and pictures that explain a lot, so if Grant& co. give >>>>> permission, or if we can do this in secret with nobody seeing... >>>>> or buy Part No. 24-127, RR 26-35! >>> >>>>> On Thu, Dec 30, 2010 at 9:21 PM, doug peterson<[email protected]> wrote: >>>>>> Does anyone have this as a PDF? Specifically looking Grant's article >>>>>> on the eternal trail question. The Atlantis& I have been out messing >>>>>> with loading again....the things you start mulling about during >>>>>> winter... >>> >>>>>> dougP >>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google Groups >>>>>> "RBW Owners Bunch" group. >>>>>> To post to this group, send email to [email protected]. >>>>>> To unsubscribe from this group, send email to >>>>>> [email protected]. >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/group/rbw-owners-bunch?hl=en. >>> >>>>> -- >>>>> 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 [email protected]. >>>>> To unsubscribe from this group, send email to >>>>> [email protected]. >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/rbw-owners-bunch?hl=en.- 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 [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/rbw-owners-bunch?hl=en. >> >> > > > > -- > Patrick Moore > Albuquerque, NM > For professional resumes, contact > Patrick Moore, ACRW at [email protected] > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > 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. 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