Front derailleur clamp size
08-02-18, 03:01 PM
#1
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Front derailleur clamp size
I've an old (1999) Lemond Zurich frame that I'm restomodding. I'll be putting Ultegra R8000 on the thing. The front derailleur is available for a braze-on, or as a clamp. The frame does not have a braze-on tab, The size of the two clamp sizes listed for Shimano FDs are 21.6-31.8mm, or 34.9mm. But the seat tube in a Lemond is 32-32.1 mm.
0) Did I mis-measure, and is the tube really a 31.8mm?
1) Will the smaller clamp work?
2) If not, are there appropriate after-market clamps for 32mm tube that mimic a braze-on tab?
3) If not, are there shims available that would allow me to bridge the 2.9mm diametral difference so that I could use a 34.9mm clamp? Is it that simple, just using a 1.45mm shim?
4) If not, can an FD tab easily be welded to the frame without damage? It's an 853 frame.
Thanks.
0) Did I mis-measure, and is the tube really a 31.8mm?
1) Will the smaller clamp work?
2) If not, are there appropriate after-market clamps for 32mm tube that mimic a braze-on tab?
3) If not, are there shims available that would allow me to bridge the 2.9mm diametral difference so that I could use a 34.9mm clamp? Is it that simple, just using a 1.45mm shim?
4) If not, can an FD tab easily be welded to the frame without damage? It's an 853 frame.
Thanks.
08-02-18, 03:31 PM
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I suspect that your 31.8mm seat tube has 0.1-0.15mm (measured twice) of paint on it, making the total 32.0-32.1mm.
08-02-18, 03:36 PM
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0) Probably. Perhaps someone with the same bike can chime in.
1) No.
2) Probably. There's a lot of wild stuff out there. More all the time.
3) Probably, or you can make your own from "generic shim stock" (soda can).
4) No.
1) No.
2) Probably. There's a lot of wild stuff out there. More all the time.
3) Probably, or you can make your own from "generic shim stock" (soda can).
4) No.
08-02-18, 04:07 PM
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I may give the small band a shot.
08-02-18, 10:38 PM
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It will probably fit, but if you are not happy with it, just sand out the diameter .006/.008 of an inch larger. I have a mountain bike with Columbus max tubing that is slightly oval. Sandpaper on soft aluminum does wonders to get it to a particular shape.
The other route is to get 34.9 and use Shimano plastic derailleur clamp shims and sand the shims to fit. I had a tough fit to get a chainline I wanted and have the derailluer shift to the inner chainring. Took a 34.9 to 28.6 shim set and sanded the shims to be slightly offset to bring the derailleur clfrom the seat tube.
The other route is to get 34.9 and use Shimano plastic derailleur clamp shims and sand the shims to fit. I had a tough fit to get a chainline I wanted and have the derailluer shift to the inner chainring. Took a 34.9 to 28.6 shim set and sanded the shims to be slightly offset to bring the derailleur clfrom the seat tube.
08-02-18, 10:43 PM
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Since I once again accidentally hit submit reply on my phone and BF's Big Lots software won't let me edit, I will continue.
... I basically sanded the shims so the derailleur sat closer to the seat tube and moving it just enough to shift to the inner ring. After all the shims are plastic.
John
... I basically sanded the shims so the derailleur sat closer to the seat tube and moving it just enough to shift to the inner ring. After all the shims are plastic.
John
08-03-18, 09:18 AM
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Well, I ordered the small clamp version. Will see if this works,
Regarding mismeasuring, I used a Starrett caliper (the US made 797, not the Chinese 799) and am pretty sure I got a pretty accurate number. I'm hoping that there's 0.3mm tolerance in the thing. Else, I have to sand or buy the larger one and clamp.
So is it difficult to weld to 853? Is this an allow that requires post weld heat-treat?
PS I had to order the whole groupset, plus the small banded version of the FD. So I'll have a brand-new RD8000 FD for sale....
Regarding mismeasuring, I used a Starrett caliper (the US made 797, not the Chinese 799) and am pretty sure I got a pretty accurate number. I'm hoping that there's 0.3mm tolerance in the thing. Else, I have to sand or buy the larger one and clamp.
So is it difficult to weld to 853? Is this an allow that requires post weld heat-treat?
PS I had to order the whole groupset, plus the small banded version of the FD. So I'll have a brand-new RD8000 FD for sale....
Last edited by WizardOfBoz; 08-03-18 at 09:31 AM.
08-03-18, 10:39 AM
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If it's like the Shimano FD I recently purchased, it will come with one clamp and two sets of shims. One shim set was too thin, the other too thick. I inserted the thicker set, and I could easily get the clamp bolt to squeeze it down for a good, solid mount.
08-03-18, 11:11 AM
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Shimano Braze On Adaptor | Chain Reaction Cycles
-Tim-
08-03-18, 11:33 AM
#11
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Powder coating of a handlebar required me to sand some off,
to fit a 22.2 grip shift on it ..
it measured 22.5, originally..
to fit a 22.2 grip shift on it ..
it measured 22.5, originally..
08-13-18, 09:40 AM
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I ended up touching up the paint as the previous owner somehow thought that cream-colored paint would mask the chips in the brilliant, titanium white paint on the underside of the top tube. Looked horrible, so I wet-sanded down the paint with 600 grit SiCarbide paper, and used white urethane enamel. Overcoated with clear enamel. Looks pretty good. I could use some automotive cutting compound, and some carnauba wax.
The paint was all bunched up under the original derailleur. I did the same wet-sanding and refinishing on that area as well, and the clamp-on derailleur fits perfectly. Will post a pic when I get the thing on the stand next.
The paint was all bunched up under the original derailleur. I did the same wet-sanding and refinishing on that area as well, and the clamp-on derailleur fits perfectly. Will post a pic when I get the thing on the stand next.
