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Shimano front derailleur top pull madness

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Shimano front derailleur top pull madness

Old 07-01-20, 02:52 PM
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icepick_trotsky 
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Shimano front derailleur top pull madness

Hi all. It's been a long while since I posted on this forum, since I haven't been wrenching much. But I have a new project and I have already run into a headscratcher. That's why we do it, right?

I'm installing a front derailleur on a Bianchi Volpe. Early nineties I'm guessing. It came originally with Suntour command shifters and components, including a top pull FD. Then I set it up as a 1x10 with 10 speed shimano 105 (5700 series). Now I added a double crank and I want to use a FD with the shimano shifter, but need a compatible top pull derailleur.

Most of the top pull FDs around are mountain bike triples. I recall that Shimano 6-10 speed road and mountain stuff was cross-compatible for the rear shifter/derailleur (with some exceptions), but I seem to recall that was not the case for the FD. Is that right? Is there a top pull derailleur that will fit the bill?
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Old 07-01-20, 03:40 PM
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Yes, the cable pull is different between Shimano's road and mtb derailleurs. I think it also changed between 10- and 11-speed road. For a double, there's a very good chance you could make it work. I once got a triple to shift tolerably with Tiagra shifters and a Deore front derailleur.

That said, there is one option. Shimano makes a top-pull front derailleur for cyclocross bikes. https://bike.shimano.com/en-EU/produ...-CX70-F-T.html It's probably optimized for a 46-36 crank, but I expect you could make it work with other combinations.
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Old 07-01-20, 04:46 PM
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There is also a bolt on pulley that allows you to use any bottom pull FD.

Edit: Here is a link to one. https://www.universalcycles.com/shop...&category=1613
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Old 07-01-20, 06:42 PM
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Maybe this one...

https://bike.shimano.com/en-EU/produ...-CX70-F-T.html

John

Edit Added: Didn't notice this recommendation was already given. If you need one you'll probably have to go to eBay and buy international.

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Old 07-01-20, 08:19 PM
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Um, does the cable pull matter if it's only a double?
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Old 07-01-20, 09:02 PM
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Originally Posted by madpogue View Post
Um, does the cable pull matter if it's only a double?
Yes, no, maybe, it depends.

I "think" that mountain bike front trigger shifters pull more cable because the front derailleur attach point is further away from the pivot so it makes it easier to push the thumb shifter. Road and mountain chainrings are spaced the same. If the road brifter does pull less cable it won't move the derailleur enough to make the shift. I think this is true, but I don't mind if someone corrects me.

There "could" be a work around to be able to use a MTB front derailleur. There was a thread on MTBR years ago where someone used an XT-732 front derailleur and attached the cable to the opposite side. Everything depends on the orientation of the attach pinch bolt. If it moves it closer to the pivot it might work. In the MTBR thread it did. I have an XTR-901 on one of my mountain bikes and can see how swapping the cable to the other side has potential.

John

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Old 07-01-20, 10:40 PM
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Originally Posted by 70sSanO View Post
If the road brifter does pull less cable it won't move the derailleur enough to make the shift.
Oh, didn't realize it was a brifter in play. I read "Shimano shifter" in the opening post, and just assumed we were talking downtube.
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Old 07-01-20, 10:47 PM
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Originally Posted by madpogue View Post
Oh, didn't realize it was a brifter in play. I read "Shimano shifter" in the opening post, and just assumed we were talking downtube.
I understand. Iím running XTR-900 front and rear derailleurs on my road bike with downtube shifters. Itís like running a wide range Dura Ace.

John
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