Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

How do Trek downtube shifters mount on carbon tubes?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

How do Trek downtube shifters mount on carbon tubes?

Old 02-11-21, 07:28 PM
  #1  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 940
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked 85 Times in 63 Posts
How do Trek downtube shifters mount on carbon tubes?

So I have this Trek 2100 carbon frame with these downtube shifter mounts. The left mount is just a bit loose. It looks like it mounts with a screw which likely runs through to the other side. But I am not sure. I can't see in there well. How do these mounts...umm....mount and how can I make it secure?

Jicafold is offline  
Old 02-11-21, 07:35 PM
  #2  
Russ Roth
Senior Member
 
Join Date: Dec 2019
Location: South Shore of Long Island
Posts: 2,113

Bikes: 2010 Carrera Volans, 2015 C-Dale Trail 2sl, 2017 Raleigh Rush Hour, 2017 Blue Proseccio, 1992 Giant Perigee, 80s Gitane Rallye Tandem

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 798 Post(s)
Liked 640 Times in 482 Posts
Usually the base is epoxied and the mount is riveted to that. Might need to see a dealer on that, some with have the tools to fix it.
Russ Roth is offline  
Old 02-11-21, 09:50 PM
  #3  
cxwrench
Senior Member
 
cxwrench's Avatar
 
Join Date: Jul 2013
Location: Nor-Cal
Posts: 3,530

Bikes: lots

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 1782 Post(s)
Liked 2,617 Times in 1,355 Posts
That's an old one. I always thought they were just bonded on.
cxwrench is offline  
Old 02-11-21, 10:18 PM
  #4  
ScottRiqui 
Senior Member
 
Join Date: Jun 2020
Posts: 92
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
Liked 34 Times in 22 Posts
Originally Posted by Jicafold View Post
So I have this Trek 2100 carbon frame with these downtube shifter mounts. The left mount is just a bit loose. It looks like it mounts with a screw which likely runs through to the other side. But I am not sure. I can't see in there well. How do these mounts...umm....mount and how can I make it secure?

Is the "Trek" logo that starts next to the mount a decal or a badge? It might just be the angle and the lighting, but it really seems to "pop" off of the tube.
ScottRiqui is offline  
Old 02-11-21, 10:36 PM
  #5  
veganbikes
Clark W. Griswold
 
Join Date: Mar 2014
Location: ,location, location
Posts: 10,219

Bikes: Foundry Chilkoot Ti W/Ultegra Di2, Salsa Timberjack Ti, Cinelli Mash Work RandoCross Fun Time Machine, 1x9 XT Parts Hybrid, Co-Motion Cascadia, Specialized Langster, Phil Wood Apple VeloXS Frame (w/DA 7400), R+M Supercharger2 Rohloff, Habanero Ti 26

Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 2981 Post(s)
Liked 2,208 Times in 1,459 Posts
It is probably bonded/glued to the tubes. Maybe a rivet is in there as well. There is a member on the forums who worked for Trek back in the day but I can't remember name maybe JohnDThompson but I could be wrong (Sorry John if I am wrong or if you don't know).

You might consider reaching out to trek or finding an older Trek dealer they might know.
veganbikes is offline  
Old 02-12-21, 07:40 AM
  #6  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 940
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked 85 Times in 63 Posts
Originally Posted by ScottRiqui View Post
Is the "Trek" logo that starts next to the mount a decal or a badge? It might just be the angle and the lighting, but it really seems to "pop" off of the tube.
It's a decal.

Originally Posted by Russ Roth View Post
Usually the base is epoxied and the mount is riveted to that. Might need to see a dealer on that, some with have the tools to fix it.
That's true. Could be a rivet. It's loose and yet not coming off so it must be something other than glue.
Jicafold is offline  
Old 02-12-21, 08:10 AM
  #7  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,213

Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1714 Post(s)
Liked 1,793 Times in 1,111 Posts
I can’t speak for a 2100, but Cannondale used a threaded rod to pinch the 2 shifter bosses together against the downtube.

I believe the 2100 is epoxied, but it may also have a threaded rod for more support. What I don’t know is how the bosses come apart.

If the concern is keeping the boss from being loose, I would guess an epoxy could be used; but I wouldn’t want to guess which one to use.

John
70sSanO is offline  
Old 02-12-21, 08:30 AM
  #8  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 940
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked 85 Times in 63 Posts
Originally Posted by 70sSanO View Post
I canít speak for a 2100, but Cannondale used a threaded rod to pinch the 2 shifter bosses together against the downtube.
Yes, the Cannondale does use a threaded rod. I'm considering that as a repair for this one. Of course that may involve using a nut on the outer ends of the shifters. Even if I switch to brake/shift levers I'd still have to secure those cable mounts.
Jicafold is offline  
Old 02-12-21, 09:14 AM
  #9  
HillRider
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,409

Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1893 Post(s)
Likes: 0
Liked 872 Times in 616 Posts
Originally Posted by 70sSanO View Post
I canít speak for a 2100, but Cannondale used a threaded rod to pinch the 2 shifter bosses together against the downtube.
So did the Trek- built Kleins from the late 1990's. There was a thin threaded rod that passed through the bosses and the downtube along with double sided tape to hold the bosses in place. The rod had a screwdriver slot accessible at the bottom of the threaded shifter mounting hole. These rods tended to vibrate loose and/or strip the threads which allow the bosses to fall off. Trek sold repair kits for a while.
HillRider is offline  
Old 02-12-21, 09:26 AM
  #10  
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 23,745

Bikes: Several, mostly not name brands.

Mentioned: 142 Post(s)
Tagged: 0 Thread(s)
Quoted: 3045 Post(s)
Liked 2,170 Times in 1,295 Posts
Yes, there is a rod that passes through the tube to the boss on the other side. The curved bases are epoxied to the tube to prevent any wiggling of the boss in use.
JohnDThompson is offline  
Old 02-12-21, 10:20 AM
  #11  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 940
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked 85 Times in 63 Posts
Originally Posted by HillRider View Post
There was a thin threaded rod that passed through the bosses and the downtube along with double sided tape to hold the bosses in place. The rod had a screwdriver slot accessible at the bottom of the threaded shifter mounting hole. .
Thank you. If I canít get this out Iíll have to drill it out.
Jicafold is offline  
Old 02-13-21, 01:39 PM
  #12  
Jicafold
Senior Member
Thread Starter
 
Join Date: Jun 2013
Posts: 940
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked 85 Times in 63 Posts
So I drilled it out. I don't think that any kind of adhesive, epoxy would be strong enough to hold this on. JB Weld? I dunno. I'll need a skinny threaded rod to run through there and 2 nuts on the end...which would prohibit me from using downtube shifters but I could put on the cable mounts for the brake/shift levers. And I am going to lightly sand and clear coat the carbon tubes because of the flaking.

Jicafold is offline  
Old 02-13-21, 10:57 PM
  #13  
Camilo
Senior Member
 
Join Date: Apr 2007
Posts: 5,682
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 657 Post(s)
Liked 540 Times in 351 Posts
I have no idea if threaded rod of that small diameter is available, but if not, you could make "treaded rod" out of an appropriate diameter bolt by cutting off the head and dressing the threads on that end.
Camilo is offline  
Old 02-13-21, 11:56 PM
  #14  
wesley77803
Member
 
Join Date: Oct 2016
Location: Texas
Posts: 29

Bikes: 1989 Trek 660, 1985 Trek 620

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked 10 Times in 5 Posts
Originally Posted by Jicafold View Post
So I drilled it out. I don't think that any kind of adhesive, epoxy would be strong enough to hold this on. JB Weld? I dunno. I'll need a skinny threaded rod to run through there and 2 nuts on the end...which would prohibit me from using downtube shifters but I could put on the cable mounts for the brake/shift levers. And I am going to lightly sand and clear coat the carbon tubes because of the flaking.
Originally Posted by Camilo View Post
I have no idea if threaded rod of that small diameter is available, but if not, you could make "treaded rod" out of an appropriate diameter bolt by cutting off the head and dressing the threads on that end.
If you can find or make a long enough rod that is M5 you may be able to keep the downtube shifters. Cut a slot in the M5 rod so you can use a screw driver to turn it. (Possibly one on each end.) The big question is: is the distance between the innermost set of M5 threads on the two bosses an even number of threads.

Cut the rod to a length that will allow it to go through the tube and into the bottom 3 to 5 threads on each boss. Thread the rod into one of the bosses. Set the bosses in place and clamp them (check the fit dry then the final assembly would use epoxy to hold the bosses). Then screw the rod into the second boss. Make sure the rod is evenly spaced to give the same number of available threads in both bosses. You may need to increase clamp pressure to squeeze the tube to flex it so the rod will fit into second boss. You may also need to shim under the boss depending on how close to an even number of threads fit between the bosses.

After the epoxy is set, you should still be able to install the downtube shifters although you might need to shorten the bolts holding the shifters in place.
wesley77803 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.