Glad to hear you got rid of the slippage, Mike. On Monday, August 27, 2012 7:21:35 AM UTC-7, Mike wrote: > > Hey William, thanks so much for pointing out that a shorter bolt holding > the shifter to the braze-on might take care of the slippage. I hadn't > ridden my randonneuring bike since finishing the Cascade back in June. > Yesterday before heading out to Larch Mtn I filed the bolt down put it back > on my bike and headed out for a ride where I was able to enjoy standing up > and riding in the big ring with the shifter slipping. > > --mike--who is looking forward to going back to DT shifters on his Hilsen. > > On Monday, July 2, 2012 11:22:42 AM UTC-7, William wrote: >> >> Mike >> >> This is a very common issue with several very simple fixes. I apologize >> in advance for a long post >> >> As you know, there's a spring in the front derailer that wants to pull >> the chain down to the small ring. The only thing stopping that from >> happening is the friction in the shiftlever. If there's more static >> friction in the shiftlever, it'll keep the front derailer in place. If the >> force in the derailer spring is stronger, it'll win and pull the chain >> over. When you pedal out of the saddle, the frame flexes some and makes >> the cable a little tighter a little looser in phase with your pedalling. If >> the friction in the lever is just barely strong enough to hold the derailer >> in place, this part can make the derailer walk down to where it's >> constantly rubbing and requires you to pull the shifter again to take up >> the slack. >> >> This problem is more common these days because modern front derailers >> have ridiculously strong return springs because of all the mashers who >> insist on being able to downshift to a smaller chainring while hammering >> out of the saddle. Furthermore, the lever arm on the ft derailer linkage >> is much shorter today than in older derailers, making the front derailer >> 'stronger' because of an increased mechanical advantage. This >> 'enhancement' developed to get brifters to work. So the fixes can include: >> >> 1. If you have a 'modern' front derailer, consider swapping it with an >> older design. One with a lighter spring and/or longer lever arm >> 2. Get more friction out of your friction shifter. If you tighten up >> the d-ring all the way, you should no longer even be able to move your >> shifter in the downshift direction. If you can't do that, then you aren't >> really tightening the friction part of your shifter. You've merely >> bottomed out on the bolt and you are tightening against that. You need a >> shorter bolt, or a slightly thicker friction washer inside. >> 3. Another modern front derailer 'enhancement' is a SUPER narrow cage. >> One of the consequences of that is you have to have your limit screws set >> really precisely, and you have to slam the derailer against the limit screw >> when you are in the big ring and a smallish cog. In this situation, the >> tug-of-war is no longer the front derailer spring against the shifter >> friction. It's an immovable object (the limit screw) against the friction >> in your shifter. The limit screw always wins, and you'll always be able to >> get a tiny bit of slack in the cable. To check if this is what you are >> experiencing, deliberately back off the upper limit screw a lot. Like a >> full 360 degree rotation. You'll have to be careful not to overshift when >> you go into the big ring. When in the big ring, see if you can make the >> rubbing happen. You might not be able to. If you find that backing off >> the limit screw 'solves' the problem, then you'll be left trying to find a >> balance where there's a combination of limit screw setting + technique that >> keeps you from overshifting and avoids this phenomenon. Another surprising >> fix for this particular corner case is flexier shift cables. People forget >> how springy shift cables used to be. These days, they are super stiff in >> tension to make indexing work. A springier cable can take the stress >> cycles associated with pedaling without moving the shifter. It's hard to >> find springy shift cables, these days, though. >> >
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