Frame Friction Shifter Problems

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mattraisin
Posts: 73
Joined: 23 Feb 2010, 6:15am

Frame Friction Shifter Problems

Postby mattraisin » 14 Aug 2011, 3:14am

I have an Old 5 Speed Claud Butler racing bike that I have been cleaning up and recently I have struggled with the Frame Shifter. It will go into gear and then slip off and sit between two of the rings and repeat. With some very sensitive adjusting I can get it to sit in gear but I am afraid of putting the power down in case it goes. I am pretty sure this wasn't a problem before so I am not sure what caused it. Any ideas? It is fine in the highest and lowest positions but the middle 3 are tetchy.
A puncture in the middle of nowhere simply gives you more time to admire the view.

thirdcrank
Posts: 28008
Joined: 9 Jan 2007, 2:44pm

Re: Frame Friction Shifter Problems

Postby thirdcrank » 14 Aug 2011, 7:33am

Is the lever properly assembled? I'm not really clear what the you are experiencing but a traditional friction lever is infinitely adjustable between the limits of its movement. If the lever is too tight, fine adjustment may be difficult, if it's too loose, the mech may be able to move out of gear.

Depending on how old the frame is, have you got an incompatible lever / mech combination? Pre-parallelogram levers had to pull a lot more cable and so the pulley part of the lever on, say, an old Simplex or Benelux lever will have a much greater diameter and will shift gears with only a small movement.

The only other thing I can think of is the outer cable not fitting properly at the stops.

james01
Posts: 2021
Joined: 6 Aug 2007, 4:48am

Re: Frame Friction Shifter Problems

Postby james01 » 14 Aug 2011, 8:32am

Your system is one of the most simple and reliable there is. If the friction adjuster is set so that it's gripping correctly, then apart from Thirdcrank's checklist above I'd also check the geometry of the mech: is it running out of line with the chain due to old damage/wear to the mech and/or dropout? Are there any bent teeth on the freewheel? Another old favourite is wear in the freewheel bearings - you can set it up to run perfectly on a stand, but as soon as you put the pedal pressure on, the block can deviate by a couple of millimeters, enough to throw the chain off.

cromo
Posts: 56
Joined: 3 Aug 2009, 9:10am

Re: Frame Friction Shifter Problems

Postby cromo » 14 Aug 2011, 10:22am

It could be that on cleaning the bike something (bike cleaner or lubricant) has got into the friction mechanism. I did have a similar problem and had to strip down the
mechanism and wipe off anything that might interfere with friction between the surfaces.

thirdcrank
Posts: 28008
Joined: 9 Jan 2007, 2:44pm

Re: Frame Friction Shifter Problems

Postby thirdcrank » 14 Aug 2011, 11:30am

cromo's post is a reminder of an alternative approach: instead of think what might be wrong, think through everything you have done which might have changed something - you do think it was Ok before you worked on it. Cleaning a gunged-up drivetrain can expose problems the gunge was suppressing.

mattraisin
Posts: 73
Joined: 23 Feb 2010, 6:15am

Re: Frame Friction Shifter Problems

Postby mattraisin » 14 Aug 2011, 2:21pm

What it was doing was sitting on top and not engaging. Replaced the freewheel with a different one that I know not to be very worn and the problems seem to have gone. It was obviously a not very worn chain when I got it but there is a posibilty that it is the wrong speed chain and the wear on the other one made that problem worse. The current one will sit on top and not engage but only in the stand and not when out riding. Thanks for the help. Any thoughts on what could cause it to sit on top appreciated though.
A puncture in the middle of nowhere simply gives you more time to admire the view.

thirdcrank
Posts: 28008
Joined: 9 Jan 2007, 2:44pm

Re: Frame Friction Shifter Problems

Postby thirdcrank » 14 Aug 2011, 8:13pm

If by 'sit on top' you mean that the chain sometimes runs along the top of the teeth of a sprocket instead of the teeth engaging the chain, that used to be a regular feature of non-indexed gears.