bottom-pull FD on a top-pull frame? how?
#1
Amazing, but true...
Thread Starter
bottom-pull FD on a top-pull frame? how?
I was transferring components from a full-sus. mtb onto a new frame. it has a sram bottom-pull FD, and the new frame doesn't have routing under the BB, only a top-pull stop on the seat tube. is there anyway to make this FD work with this frame? am i missing something? do they make some kind of pulley to adapt it? suggestions appreciated, as are specific part number from qbp, hawley, or bti
#2
surly old man
Join Date: Sep 2006
Location: Carlisle, PA
Posts: 3,392
Bikes: IRO Mark V, Karate Monkey half fat, Trek 620 IGH, Cannondale 26/24 MTB, Amp Research B3, and more.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Likes: 0
Liked 42 Times
in
18 Posts
You can buy a cheapo plastic under BB router. From the factory they are screwed or riveted on. But since the tension of the cable(s) tends to keep in place you could just put a dab of silicon glue (or somesuch) under it to keep in place.
You would still need a cable stop for it on the downtube. They do sell clip and bolt-on ones.
jim
jim
You would still need a cable stop for it on the downtube. They do sell clip and bolt-on ones.
jim
jim
__________________
Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
--------------------------
SB forever
Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
--------------------------
SB forever
#3
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,656
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: 2026 Post(s)
Likes: 0
Liked 1,096 Times
in
742 Posts
My early '90's Trek MTB came with a bottom pull fd and routed the cable along the top tube and down the seat tube.
To make it work they added a anchor bolt just above the bottom bracket at the back of the seat tube to attach the inner cable end. Then, the fd (a Deore LX) had it's anchor bolt replaced by an adapter that accepted the end of the cable housing from above. So, front shifting is accomplished by the housing being pushed down on top of the fd's arm. It's easy to see but tough to explain.
To make it work they added a anchor bolt just above the bottom bracket at the back of the seat tube to attach the inner cable end. Then, the fd (a Deore LX) had it's anchor bolt replaced by an adapter that accepted the end of the cable housing from above. So, front shifting is accomplished by the housing being pushed down on top of the fd's arm. It's easy to see but tough to explain.
#4
Surf Bum
Join Date: Aug 2008
Location: Pacifica, CA
Posts: 2,184
Bikes: Lapierre Pulsium 500 FdJ, Ritchey breakaway cyclocross, vintage trek mtb.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Likes: 0
Liked 5 Times
in
3 Posts
Many cyclocross bikes route the front derailleur cable along the top tube and still use a "bottom pull" derailleur. There are pulleys that mount below the derailleur to make this possible. They even make clamp on type for bikes that originally weren't designed for that routing.
Like this one: https://cyclocrossworld.stores.yahoo....ipu34news.html
Like this one: https://cyclocrossworld.stores.yahoo....ipu34news.html
#5
Senior Member
I have this situation on my current Schwinn hybrid. I made my own direction change pulley out of a 3- speed aluminum guide pulley and a handmade frame clamp. Allows you to operate a bottom pull front derailler on a frame designed for top pull deraillers.
The pics aren't the greatest quality but do show you what I did:
Enjoy!
The pics aren't the greatest quality but do show you what I did:
Enjoy!
#6
Senior Member
Join Date: Apr 2008
Location: A Latvian in Seattle
Posts: 1,020
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
It might be cheaper (and easier) just to install a new FD. I've had good luck with the X Gens (which can handle either top or bottom pull, and come with shims for all 3 standard seat tube sizes). It's hard to beat $9 + shipping: https://shop.vendio.com/benscycle/ite...753/index.html
#7
Senior Member
Join Date: Aug 2008
Location: Madison, WI
Posts: 811
Bikes: '08 Trek 7.3FX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Are you sure that particular FD isn't dual pull to begin with? Some FDs can do bottom OR top pull without any sort of adapter. The one on my 7.3fx is like this, a top swing dual pull.
Do a Google search on the model FD and see what pops up...
Do a Google search on the model FD and see what pops up...