Front derailleur clamp size
08-02-18, 03:01 PM
#1
Generally bewildered
Thread Starter
Join Date: Aug 2015
Location: Eastern PA, USA
Posts: 2,973
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1121 Post(s)
Liked 307 Times
in
230 Posts
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
#2
Senior Member
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,317
Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta
Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1437 Post(s)
Liked 1,085 Times
in
720 Posts
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
#3
Senior Member
Join Date: Jan 2015
Location: Richmond, Virginia
Posts: 8,781
Bikes: Waterford Paramount Touring, Giant CFM-2, Raleigh Sports 3-speeds in M23 & L23, Schwinn Cimarron oddball build, Marin Palisades Trail dropbar conversion, Nishiki Cresta GT
Mentioned: 65 Post(s)
Tagged: 0 Thread(s)
Quoted: 2556 Post(s)
Liked 2,083 Times
in
1,354 Posts
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
#4
Generally bewildered
Thread Starter
Join Date: Aug 2015
Location: Eastern PA, USA
Posts: 2,973
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1121 Post(s)
Liked 307 Times
in
230 Posts
I may give the small band a shot.
08-02-18, 10:38 PM
#6
Senior Member
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,446
Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1815 Post(s)
Liked 1,965 Times
in
1,205 Posts
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
#7
Senior Member
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,446
Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1815 Post(s)
Liked 1,965 Times
in
1,205 Posts
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
#8
Generally bewildered
Thread Starter
Join Date: Aug 2015
Location: Eastern PA, USA
Posts: 2,973
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1121 Post(s)
Liked 307 Times
in
230 Posts
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
#9
Senior Member
Join Date: Feb 2005
Location: St. Louis
Posts: 261
Bikes: 2011 Surly LHT, 2007 Specialized Roubaix, 2004 Giant Cypress, 1990 Simoncini Super Professional
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
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
#10
- Soli Deo Gloria -
Join Date: Aug 2015
Location: Northwest Georgia
Posts: 14,782
Bikes: 2018 Rodriguez Custom Fixed Gear, 2017 Niner RLT 9 RDO, 2015 Bianchi Pista, 2002 Fuji Robaix
Mentioned: 235 Post(s)
Tagged: 0 Thread(s)
Quoted: 6840 Post(s)
Liked 729 Times
in
463 Posts
Shimano Braze On Adaptor | Chain Reaction Cycles
-Tim-
08-03-18, 11:33 AM
#11
Banned
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
#12
Generally bewildered
Thread Starter
Join Date: Aug 2015
Location: Eastern PA, USA
Posts: 2,973
Bikes: 2014 Trek Domane 6.9, 1999 LeMond Zurich, 1978 Schwinn Superior
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1121 Post(s)
Liked 307 Times
in
230 Posts
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.
