front derailer...

[Simon Llewellyn]

Hey guys I just swapped my cranks on my cervelo to ultegra 170mm 53/39 & no matter what I do the chain touches the front derailer... Whether it is on the 39 chainring & the 23 cog, then if I prevent that then it touches on the 53 chainring and 11 cog.. It's almost like I have to choose between big gears or small gears?

I remember on the compact it used to touch to. Is there a solution? or is it just fine tuning to perfection?

[weiyun]

Is there no trimming feature on the brifter? I understand that some Shimano brifters have a half position setting. Although not fully tested, a slight change in the cable clamp position (on the cable) may also have an influence on this problem, or just use the in-line cable tensioner if you have it on the bike.

[Grant Bond]

Is the cage length/ curvature appropriate for the 53 or is it "compact specific"?- Assume you have moved it up to give a 2-3mm gap to the 53?

[weiyun]

CT FD should have no problems handling a regular double in theory. Not sure if there's something peculiar with Shimano's CT FD design.

[T-Bone]

shimano doesn't have a compact front derailleur, and i find they're a waste of time anyway, as a normal front derailleur will work fine, the only situation it may not is when the mount is fixed and doesn't provide for a large enough range in adjustment to get sufficient drop to the compact chainrings.

Anyway, there shouldn't be any touching, if there is it should only occur in extreme cross chaining (53-23). Use the shimano instructions for adjusting the derailleur, following them gives perfect adjustment. From memory you adjust the inner limit screw before attaching cable, so that chain is not rubbing when in 39-23 (23 is your biggest cog right?). Then attach cable, taking up as much slack as possible in the process, and use the cable adjustment screw to take up the remainder (can't remember if cervelo have any of these....), otherwise a cable puller might be useful. Next, shift onto 53-11, and adjust outer limit screw so chain is not rubbing. Think that's about it.

[Simon Llewellyn]

I'll give it a go. I think I"ll just take it down to the track tomorrow night and get the advice of grand master technician Munksy for some support...

[weiyun]

I'll give it a go. I think I"ll just take it down to the track tomorrow night and get the advice of grand master technician Munksy for some support...

May I guess that you are a track fixie rider?

[Simon Llewellyn]

May I guess that you are a track fixie rider?

Pretty much. I ride my road bike abit but it is the designated 'racing' bike for the road. I"ve started doing all my heart rates (roller work) on it though lately, that's why I bought the shorter cranks to standardise all my bikes....

[weiyun]

So why did you buy the original bike with the longer crank?

[FAswad]

Adjust limit screws. Then adjust cable.

Hey guys I just swapped my cranks on my cervelo to ultegra 170mm 53/39 & no matter what I do the chain touches the front derailer... Whether it is on the 39 chainring & the 23 cog, then if I prevent that then it touches on the 53 chainring and 11 cog.. It's almost like I have to choose between big gears or small gears?

I remember on the compact it used to touch to. Is there a solution? or is it just fine tuning to perfection?

[Simon Llewellyn]

So why did you buy the original bike with the longer crank?

It just came standard and to swap them they wanted an extra $400 or something. So I though I would just swap them later for half the price and end up with an extra set of cranks. I plan to put the compact gearing onto my touring bike. You need smaller gears with 10kgs of paniers to get up the hills, so there was always a plan...