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I'm building up a Fuji CX frame that has top-routed cables. That means I'll need a top-pull front derailleur ...I would prefer not to use one of the small rollers to adapt a bottom pull. Any suggestions on a derailleur (31.8 clamp dia)? They seem to be hard to find unless I use a MTB part and shim it for the smaller seat tube?
 

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bcullins said:
I'm building up a Fuji CX frame that has top-routed cables. That means I'll need a top-pull front derailleur ...I would prefer not to use one of the small rollers to adapt a bottom pull. Any suggestions on a derailleur (31.8 clamp dia)? They seem to be hard to find unless I use a MTB part and shim it for the smaller seat tube?
Shimano and SRAM road and MTB front derailleurs require different amounts of cable pull. Every cross frame I have uses those pulleys to re-route the cable and they work fine. Your making it harder than it needs to be.
 

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Also an MTB derailluer cage is much longer than a road derailleur, so you would probably run into tire/derailleur clearance issues.

Just use the pulley system and a normal road derailleur.
 

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I've used

XTR on my last 3 of 4 cx bikes, have yet to have an issue
I use XTR because it will shift a 48
shifted as smooth or smoother than my Ultegra FD w/ pulley on bike 1 of 4
 

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MTB FD cages are wider too. Setup is going to be more demanding to make sure it will shift right.
 

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Like ATP, I've used an XTR with no issues, on 2 separate bikes.
 

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Like ATP and Kram, I've used an XT top pull with a 38X46 ultegra crank, and it works without a problem. The only minor issue is more careful adjustment of my 3rd eye chain guide so it doesn't interfere with the inner MTB derailleur cage. But otherwise if anything it shifts more cleanly and easily than my other bike that uses a shimano road derailleur with a pulley. The pulley can be a mud and grass catcher sometimes too.
 

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I used a dual-pull XTR-M971 on my cross bike. I am running bottom pull, but it is supposed to work top pull as well. I picked up a set of seat post shims at the LBS to fit the smaller seat tube. It works fine, no clearance issues.

Only thing I needed to do was modify the shim and the FD body a little because I mounted the crank with no spacers on the drive side to get a better (45mm) chain line. I just used a Dremel and removed a bit of aluminum that was stopping the mech. from moving closer to the frame and a small sanding drum to take about 1mm off one side of the shim. If I ran the recommended BB spacers, I would not have had to do that extra work.
 

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Shimano CX-70 front derailleur. Works better than a MTB der, and doesnt need a cable routing pulley. Comes in braze-on, clamp on for many diameters.

Can't make it any easier.
 

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Shimano CX-70 front derailleur. Works better than a MTB der, and doesnt need a cable routing pulley.
A couple considerations if running DA7900 shifters that I and the wife learned earlier this year. I thought it required a bit more effort to shift into the big chainring than when using a cable pulley setup and the wife found it required a whole lot more effort and was not always able to pull it off. Also, the deraileur cage is like ~.1-.3mm narrower than that of a FD-7900 so there may be an issue with chain rub.
 

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Pulleys always require more effort....no way around it.
With mtb derailers or the CX70 line or a Speen Adapter....there is no reason to run a roller.
Btw....we are replying to a 2 year old thread????? D'oh!
 

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Shimano CX-70 front derailleur. Works better than a MTB der, and doesnt need a cable routing pulley. Comes in braze-on, clamp on for many diameters.

Can't make it any easier.
This, cant believe it took 11 posts to get here.

edit: well ****, 2 year old thread. CX 70 wasn't on the market then....whoops
 
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