Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

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.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 05-20-06, 02:51 AM   #1
7500fx
Newbie
Thread Starter
 
Join Date: May 2006
Bikes:
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Installing a bottom pull front derailleur on a top pull cyclocross bike.

So I inherited a Trek 7500fx from my dad, and it has some Sora STI brifters on a drop bar. Now I wanted to adjust the front derailleur because you had to hold the lever to get it into the biggest cog, turns out it's a Nexave mtn derailleur, and now it won't go between more than two cogs. I check this forum and it turns out Shimano road and mtn components don't mix (except rear derailleurs from what I understand), so I go and grab a Ultegra road derailleur at the local used store. As I walk out I realise it's a a bottom pull derailleur (duh!), and the store doesn't accept returns. So how do I go about solving this problem? I have only found clamp on pulleys for smaller diameter tubes (mine's a 34.9mm). Suggestions?
7500fx is offline   Reply With Quote
Old 05-20-06, 10:08 AM   #2
grolby
Senior Member
 
grolby's Avatar
 
Join Date: Jan 2005
Location: BOSTON BABY
Bikes:
Posts: 9,376
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 106 Post(s)
Hmmm. What about a Sturmey-Archer shift cable pulley? Clamp it down by the bottom bracket, run the cable around it, it'll reverse the direction of the cable so it'll be coming up from below the derailer. Will it work? I dunno, but it might be worth a shot.

Oh, wait. Upon closer reading, I see that you have considered this and couldn't find anything that would clamp your tubes. Well, you might be able to find away to come up with a way of clamping it. I can't really think of any other way to solve the problem.
grolby is offline   Reply With Quote
Old 05-20-06, 01:55 PM   #3
head_wind
Hypoxic Member
 
head_wind's Avatar
 
Join Date: Oct 2005
Location: Colorado Springs
Bikes:
Posts: 545
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My CX bike has a welded boss for a screw to hold the pulley. I don't know the material that your frame is made of: is welding or brazing practical?? Also, wondering out loud perhaps the Zefal Gizmo Clamps would be strong enough for the pulley?? See: http://www.bikeforums.net/archive/in.../t-111754.html which leads to: http://www.nordicgroup.us/cageboss.htm. Hope that helps.
head_wind is offline   Reply With Quote
Old 05-20-06, 02:19 PM   #4
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Posts: 26,904
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
How big is your down tube?

Problem Solvers makes cnc clamp on cable stops in sizes up to 1 1/2". If that'll fit your down tube you can run your shift cable under the bottom bracket in the conventional manner. If you decide to order one through your LBS the QBP part number is BR5461. Unfortunately, they ain't cheap.
Retro Grouch is offline   Reply With Quote
Old 05-20-06, 03:05 PM   #5
7500fx
Newbie
Thread Starter
 
Join Date: May 2006
Bikes:
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ok, so the Sturmey-Archer clamp pulley was a good idea, but it only comes in 1 1/8" diameter, i need 1 3/8" (34.9mm). As for the downtube, it's one of them oval suckers so a traditional road bike cable routing won't work with clamp ons. I was actually thinking about using two clamp on cable stops and routing the cable so as to have it come around if that makes sense. More or less a pulley using cable stops and a piece of cable housing. Think this'll work? Thanks, for the help thus far.
7500fx is offline   Reply With Quote
Old 05-20-06, 08:09 PM   #6
7500fx
Newbie
Thread Starter
 
Join Date: May 2006
Bikes:
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Also, does anyone know if this thing has two stops (one on each side of the hinge it looks like) per clamp? I wouldn't want to buy two if I can get away with one.

http://www.biketoolsetc.com/index.cg...id=TK-105A/38S
7500fx is offline   Reply With Quote
Old 05-21-06, 06:12 AM   #7
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Posts: 26,904
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
Quote:
Originally Posted by 7500fx
Also, does anyone know if this thing has two stops (one on each side of the hinge it looks like) per clamp? I wouldn't want to buy two if I can get away with one.

http://www.biketoolsetc.com/index.cg...id=TK-105A/38S
Sure looks like 2 to me but I really don't know. Do you think you will have enough room beneath your derailleur for a big enough cable housing loop? You might want to check out your rear derailleur for a comparison.

What are you using for front chainrings? A Shimano Deore LX M571 downpull derailleur is rated for 48 tooth chainrings. The QBP part number in 31.8mm clamp size is FD5676. It's a big step up in quality from your old Nexave derailleur.
Retro Grouch is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 03:21 AM.