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Front detailleur shim

Old 06-15-12, 05:47 PM
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Front detailleur shim

How should I measure this, and where can I buy one?

The bike my new front derailleur came off of used a 27.2 seatpost, and the bike I want to put it on uses a 26.4.

It's a DA FD-7700 clamp on, if that matters.
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Old 06-15-12, 05:56 PM
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The clamp diameter should be stamped on the inside of the derailleur clamp, and is determined by the diameter of the Seat Tube, not the seat post.
There are three sizes of clamps; 28.6, 31.8, and 34.9 mm. Shims to make the larger clamp sizes work on smaller seat tubes are available, but only
to a degree.

Find out the clamp size, and someone will advise you forthwith.
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Old 06-16-12, 05:48 PM
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Old FD is stamped 28.6, new FD is stamped 31.8
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Old 06-16-12, 06:04 PM
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Front detailleur shim

Shimano derailleur? Your local shop probably has shims laying around.
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Old 06-16-12, 06:15 PM
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https://www.universalcycles.com/shopp...61&category=77
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Old 06-16-12, 07:28 PM
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Originally Posted by JonathanGennick
Shimano derailleur? Your local shop probably has shims laying around.
I tried both local shops, one did not have the right size and would need to order (thanks I can do that myself and avoid the return trip) and the other shop only stocks bikes/helmets/shoes/tires/tubes unfortunately, no parts.

thanks for the link to universalcycles, looks like the $6 s-type 31.8 to 28.6 is what I need.
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Old 06-17-12, 06:43 AM
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Had no idea those were sold separately. Learn something new every day, I guess.
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Old 06-17-12, 08:00 PM
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I hate how FD hangers aren't considered as de rigeur as RD hangers.

Clamp-on FDs look nearly as crappy as a RD claw to me.

And they create this problem.

The issue with integral FD hangers about an appropriate height can be addressed by making it a bit taller, for a start. Or by making it not really integral, like most carbon frames where it's rivetted or preferably bolted on through slotted holes.

Last edited by Kimmo; 06-17-12 at 08:04 PM.
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Old 06-17-12, 11:00 PM
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looking at my new FD closer I've realized it's actually a braze on mounted style with a shimano braze on 31.8 adapter, so I just ordered a 'problem solvers' braze on to 28.6 FD adapter. I think that will be cleaner/lighter and easier to setup than the 31.8 with a shim.

I agree, I think a braze on of the frame is a better idea, if the FD's were slotted for height adjustment with different chainrings it would be a whole lot easier!
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