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Top Pull FD (for road cranks)(17 posts)

Top Pull FD (for road cranks)B2
Nov 20, 2002 12:35 PM
I haven't been able to locate a 105 or Ultegra front derailleur that is a top pull (1-1/8" clamp preferred). Does Shimano (or any other mfgr) make one that's suitable for a 39/53 or similar setup?

Thanks,
Bryan
re: Top Pull FD (for road cranks)The Walrus
Nov 20, 2002 1:15 PM
Don't waste your time looking--I spent ages trying to find a top-pull road derailleur, and as far as I could tell, there isn't/wasn't any such animal. New/used, Shimano, Campy, Suntour, etc.--no luck. You'll need to come up with a pulley to mount on the seat tube below the derailleur that will reverse the direction of the cable pull. Some posters addressing this topic before managed to find Sturmey-Archer pulleys; I wound up cobbling together my own version from assorted parts. Alternatively, you could get some of those clamp-type cable stops for the down tube and re-route the cable, but they're about $20 apiece.

What kind of frame is it? From the clamp size you mentioned, it sounds like steel.
re: Top Pull FD (for road cranks)B2
Nov 20, 2002 1:43 PM
Thanks for your input. Yeah you guessed it. It's a 1996 Bontrager.

The pulley system sounds like it could be a bit delicate depneding on how you rigged it up.

I was thinking rerouting the cable might be the way to go. It doesn't look too difficult to do. I found a clamp on cable stop in the correct diameter. I just need to figure out the best way to mount the plastic cable guide that goes under the BB. Could you drill and tap it or is the shell too thin?

Bryan
re: Top Pull FD (for road cranks)Wheelz
Nov 20, 2002 3:53 PM
I'm pretty sure, if you use a Shimano XT top pull derailleur, it should work fine.
re: Top Pull FD (for road cranks)OffRoadTourer
Nov 20, 2002 5:46 PM
MTB front deraillers require a different amount of cable pull, so will not work well with road shifters. (As discussed in previous posts). I know from experience, I tried to use an XTR with STI levers and never got it going right.

What you need is this little doohickey. A purpose built pulley and clamp (available in different clamp sizes). It works extremely well for converting top-pull to bottom-pull or bottom-pull to top-pull. I bought it in Australia through Dirt Works (www.dirtworks.com.au) but I'm pretty sure it's a QBP product, available through most US stores.
re: Top Pull FD (for road cranks)OffRoadTourer
Nov 20, 2002 6:02 PM
I just remembered, it's called the "mech-verter". Best of luck...
Wow - That Looks Like Great!B2
Nov 20, 2002 8:20 PM
Looks like a better option than rerouting cables.

Thanks,
Bryan
That looks suspiciously familiar...The Walrus
Nov 20, 2002 11:38 PM
...in fact, almost exactly like what I pieced together from one of QBP's E-clamps and the pulley from a Travel Agent. Now, why weren't they selling that damned thing when I needed it?

Here's what I wound up doing...
re: Top Pull FD (for road cranks)Wheelz
Nov 21, 2002 9:05 AM
I am running XT derailleur with Ultegra shifters on my cross bike. The only thing I was not sure about, because I run a 34/48-chain ring set, is the amount of curve in the guide. I checked that last night and it should work fine for a 53/39-chain ring set up. I have not had any shifting issues with my Ultegra/XT set up. The problem may be with XTR, but I am sure that XT works fine. It'll save you a few bucks too.

wheelz
more MTB plus STIatpjunkie
Nov 21, 2002 9:59 AM
Running 48x36 double and a 48x36x26 triple w/ XTR's and no trouble if that helps. A 53 on a cross bike? Don't see the need but if it's for commuting sure. 48 x 36 is a 12 tooth jump, very similar to 53x39, and another poster was 48x 34 which is identical. Maybe won't work with road triple but I doubt it. They can cover about the same gear throws.
Brian, I have one...dcm311
Nov 20, 2002 9:03 PM
My first 'cross bike (year and a half old) came with a silver Shimano derailer labeled 105CX. I don't need it anymore, so if you're interested e-mail me and I'll dig it up and give you specifics.
Cheers,
Daniel
dcm311@~nospam~yahoo.com
also.atpjunkie
Nov 20, 2002 9:31 PM
running XTR FD on 2 cx bikes. No Problems with cable throw/pull
also.laffeaux
Nov 20, 2002 11:13 PM
There are a lot of top tube routed bikes out there that seem to shift fine. I can't imagine that the MTB deraileur would not work. Maybe they work better on triples than doubles?
also.The Walrus
Nov 20, 2002 11:44 PM
An MTB derailleur wouldn't have a problem handling up to a 48T, but B2 was talking about a 53/39 setup. XT or XTR might work, but not smoothly.
also.OffRoadTourer
Nov 21, 2002 6:48 AM
My experience with the XTR mech was actually on a road triple crankset (30/42/52T). My XTR mech is old-school (non compact drive) and doesn't seem to mind the big ring. The problem is in the throw of the derailler not being able to cover all three rings. With limit screws all the way out, it has terminal chain rub in top gear. Running a bottom bracket 1.5mm narrower results in a complete inability to access granny ring. Chain line looks good throughout. Go figure!

Have a look at http://www.shimano.com/road/flathandlebar/index.asp and you will find a front mech (no particular groupset?!) made specifically for road cranks using a MTB-style RapidFire shifter. They must make these deraillers for a reason, the systems don't appear to be 100% interchangeable.

I reckon people are having success with MTB deraillers because they are running smaller rings (like a MTB) and/or using double rings (which don't require as much derailler throw as triples). Is it fair to say a lot of cross racers use something like a 38/48 double?

So, back to B2! If you can't grab the very tasty sounding 105CX, I'd say go "mech-verter", or make your own if you think you can do one as well as Walrus (wow!). Try a MTB derailler if you have no choice, but keep your fingers crossed throughout installation!
Great AdviceB2
Nov 21, 2002 7:17 AM
Thanks everyone for the input. Photos and all, I couldn't ask for more. The options list is growing - this is good. You guys are great.

Thanks,
Bryan
re: Top Pull FD (for road cranks)mackgoo
Nov 21, 2002 10:27 AM
Is there a boss on the back of your seat tube? www.cyclo-cross.com has the pullys and you just screw it in.