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SRAM Force/KCNC Pulley Question (noob)

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SRAM Force/KCNC Pulley Question (noob)

Postby rhane » Tue Mar 29, 2011 12:34 am

Total noob looking for help: SRAM Force uses an M4 upper and M5 lower pulley diameter, ok. KCNC pulleys are M5 diameter, ok. If I actually want things to fit nicely without having to rely on magic, what is the solution to replacing the stock SRAM Force RD pulleys with KCNC ones? Can I simply take off the Force pulleys, put the KCNC ones on in their place, and then use some type of shim over the SRAM Force stock pulley upper M4 bolt in order to have a proper fitting? If so, can someone hold my hand and show me where to look for this shim? Is this even the best solution in this situation? I have no machining tools/experience and truly no idea to even know what to look for. Thanks for the help.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby Ypsylon » Tue Mar 29, 2011 7:08 am

That's not a noob question, actually. Or I am one myself.

Anyways, on the FWB shop site it says:

Compatible with all Campagnolo, SRAM (road and X-0), and Shimano rear derailleurs.


I'm figuring the way this works is that the pulley isn't actually held in place by the bolt itself, but clamped by the two cage plates.

I could be wrong though. :roll:

I've got a rival RD and KCNC pulley here, if I find the time I can try to check it out tonight, if nobody provides an answer before that.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby rhane » Tue Mar 29, 2011 8:38 pm

Actually that would really help me out. I've read some posts saying that in order for the upper KCNC pulley to work properly with SRAM derailleurs you either need to tighten the bolt more than usual or use a shim. If the hole size of the KCNC pulley is still going to be larger than the standard M4 bolts used on the SRAM RD's then would the shim be the best choice? If so, where can I buy such a shim? If I can do that I would prefer to do it that way, I just need some idea of where to look and what for.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby larry_ck » Tue Mar 29, 2011 9:35 pm

KCNC (and most other after-market) pulleys use a dia 5mm hole so you’ll need a shim, as you said in your post. Aluminium tube 5mm OD 4.1mm ID worked fine for me. In the UK (and I guess elsewhere) you can get that in small packs from a hobby shops. Just cut a piece to the pulley width and place it over the M4 bolt when you go to fit the pulley. That will keep the pulley wheel aligned. I hope this helps.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby t0ph0id » Tue Mar 29, 2011 9:49 pm

I'm tuning my Fore RD at the moment. I went for Roth Shek pulley wheels. With the Roth Shek ones you get one 4mm & one 5mm so they fit.

The problem I'm facing is replacing the M4 bolt. M5 ones are everywhere, I need to replace the M4 one because I rounded it off by accident.

If anyone know's where to get one it;d be appreciated!
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby larry_ck » Tue Mar 29, 2011 11:03 pm

For replacement jockey wheels bolts I used Carbon-Ti "X-Jockey" 16mm/19mm - Sram Red.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby Boonen » Wed Mar 30, 2011 6:45 pm

You can shim the upper pulley but there's not really a need for it. Give it a try like it is first and if you think you notice a decrease in the shifting you can always shim the bolt so there's no play in the pulley.

The bolts you should be able to get anywhere, any M4 TCS bolt will work just fine. t0ph0id, where you located? If you're in the US Fairwheel should be able to help you out, in Europe you could try Jäger in Germany or Probolt in the UK.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby UpFromOne » Sun Nov 20, 2011 12:41 am

This thread not that old, and the issue persists.

I've thought about re-tapping the 4mm threads to 5mm, so both pulleys can take the same bolt.
Might make the upper pulley slightly more stable too.
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby UpFromOne » Wed Dec 07, 2011 5:08 am

Dare I ask, has anyone ever attempted to re-tap the M4 hole to M5? Is there enough room in that pivot shaft?
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Re: SRAM Force/KCNC Pulley Question (noob)

Postby Boonen » Wed Dec 07, 2011 12:41 pm

I haven't tried it as I don't see the need but I don't think there's enough room in the insert to drill it and tap one size larger threading in there. It's really move of a pivoting rod for the outer cage then an insert.

If you're worried about the shifting performance I'd rather shim the upper pulley so it fits snugly around an M4 bolt then drill the derailleur to fit an M5. :dunno:
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