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

steel-era downtube shifters on modern aluminum frame?

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.

steel-era downtube shifters on modern aluminum frame?

Old 02-20-11, 11:48 PM
  #1  
slopvehicle
ass hatchet
Thread Starter
 
slopvehicle's Avatar
 
Join Date: Nov 2003
Posts: 1,284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
steel-era downtube shifters on modern aluminum frame?

I picked up a Performance / Nashbar aluminum road frame on the cheap. My plan is to turn it into a commuter / beater, since I have some clunky parts to spare.

I've got a set of Shimano RX 100 downtube shifters from the early 90s that I intended to use. However, when I install 'em, the mounts seem to fit poorly-- the inside curve of the chrome shifter plate (the part that contacts the frame) seems intended for smaller gauge tubing. The Al downtube on my frame isn't especially oversized, but apparently it's enough to make the shifters not seat very well against it.

Am I out of luck? I really don't want to spend a lot of money to get this project rolling.
slopvehicle is offline  
Old 02-21-11, 01:34 AM
  #2  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,319 Times in 829 Posts
Steel era is not over..
fietsbob is offline  
Old 02-21-11, 01:38 AM
  #3  
slopvehicle
ass hatchet
Thread Starter
 
slopvehicle's Avatar
 
Join Date: Nov 2003
Posts: 1,284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by fietsbob View Post
Steel era is not over..
Believe me, I know-- this is the first aluminum frame I've owned in a long time.

Anyhow, I think I answered my own question by searching elsewhere: I'm out of luck.
slopvehicle is offline  
Old 02-21-11, 01:41 AM
  #4  
tomio
Senior Member
 
Join Date: Oct 2009
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
You are talking about the curved plates that go on before the shifters right? Some of the larger diameter tubed bikes (i.e. old Cannondales) used the elusive shallow curve plates.
tomio is offline  
Old 02-21-11, 01:48 AM
  #5  
slopvehicle
ass hatchet
Thread Starter
 
slopvehicle's Avatar
 
Join Date: Nov 2003
Posts: 1,284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Yeah, it makes sense that the shallow plates are out there somewhere. But It's not what I've got...which is a bummer.

Didn't anticipate this challenge when I began assembling the project in my mind. The RX 100s were purchased on the cheap for a different frame, now sold.

I have some Campy friction shifters that might work, but I was hoping for an indexed 1x9 commuter setup.
slopvehicle is offline  
Old 02-21-11, 06:09 AM
  #6  
rccardr 
aka: Dr. Cannondale
 
rccardr's Avatar
 
Join Date: Jul 2009
Posts: 6,479

Bikes: Lots. Just...lots.

Mentioned: 178 Post(s)
Tagged: 0 Thread(s)
Quoted: 1526 Post(s)
Liked 898 Times in 437 Posts
The Cannondale plates are an option if your DT is drilled to accept them- no other way for them to work. Then you will need to take those curved pieces and make them flat- a Dremel and a grinding stone do the job very quickly since they are pretty soft. If you already have mounts brazed on, then you can re-radius the trim pieces with a Dremel- just take your time and do it slowly.
__________________
Hard at work in the Secret Underground Laboratory...
rccardr is offline  
Old 02-21-11, 06:24 AM
  #7  
rob_g
Classics lover
 
rob_g's Avatar
 
Join Date: Feb 2011
Location: Niagara, Ontario
Posts: 15

Bikes: early 90's Bianchi Trofeo, others

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by slopvehicle View Post
I've got a set of Shimano RX 100 downtube shifters from the early 90s that I intended to use. However, when I install 'em, the mounts seem to fit poorly-- the inside curve of the chrome shifter plate (the part that contacts the frame) seems intended for smaller gauge tubing. The Al downtube on my frame isn't especially oversized, but apparently it's enough to make the shifters not seat very well against it.

Am I out of luck? I really don't want to spend a lot of money to get this project rolling.
I have the same shifters, part of the complete group set on my Bianchi. It works wonderfully.

Had been looking for a more modern 8 speed Shimano indexed shifter, and noticed they are available in two model numbers - one with the more rounded flange mount, like yours; and a variant where the mount is a lot flatter, described as for modern, large diameter frames.

The one you have could be ground down (the horror!) a bit, to make it fit better. Careful work with some files could be the answer.

I was going to buy that 8 speed shifter, with the flatter mount, only because it was cheaper - about $33 (for the 'modern frame' version) versus $42 or so for old school. I would be swapping the mount with one of the older ones I have from other bikes, since I need the old style one.
rob_g is offline  
Old 02-21-11, 09:10 AM
  #8  
HillRider
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 32,859

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

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 1671 Post(s)
Likes: 0
Liked 529 Times in 396 Posts
Originally Posted by rob_g View Post
The one you have could be ground down (the horror!) a bit, to make it fit better. Careful work with some files could be the answer.
It's not a horror, it's easy. Place the bases curved side down on a flat sheet of sandpaper and sand them until they fit.

I have a set of 8-speed Shimano dt shifters mounted on Kelly Take-Off adapters that require a completely flat base mounting plate. Chris Kelly used to supply these by taking regular mounting plates and grinding them down. They work fine.
HillRider is offline  
Old 02-21-11, 09:54 AM
  #9  
rob_g
Classics lover
 
rob_g's Avatar
 
Join Date: Feb 2011
Location: Niagara, Ontario
Posts: 15

Bikes: early 90's Bianchi Trofeo, others

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by HillRider View Post
It's not a horror, it's easy. Place the bases curved side down on a flat sheet of sandpaper and sand them until they fit.
That sounds like a great way to do it, HillRider. Good tip!
rob_g is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
taguy4
Classic & Vintage
4
09-16-17 09:35 PM
impulse7675
General Cycling Discussion
12
08-10-17 06:12 AM
daf1009
Bicycle Mechanics
7
03-22-11 06:47 PM
ptle
Bicycle Mechanics
25
11-23-10 01:33 PM
stevegor
Bicycle Mechanics
9
04-22-10 01:22 PM

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.