Six jours

For various irrational but otherwise perfectly valid reasons I'd like to use Dura-Ace 9 speed downtube indexing shift levers and a 32 or 34 tooth maximum cog. As far as I can tell those cogs require a "mountain bike" derailleur. The spec sheets for Shimano's mountain bike derailleurs usually say something like "Compatible with all mountain bike shifters" so I'm not convinced the DT shifters will work with the off-road derailleurs.

Anybody know the facts?

NeilGunton

It's funny you should bring this up now, because I just had this very discussion with Shimano a couple of days ago myself. Recounted on this thread over on crazyguyonabike:

https://www.crazyguyonabike.com/forum...read_id=185783

In a nutshell, I had 9-speed Dura Ace bar end shifters (i.e. "road" shifters) combined with the Shimano XTR RD-M971 rear derailleur (i.e. a "mountain" derailleur). I was getting problems with ghost shifting - if I dialed it in at one end, then it would start skipping on the other end. Shimano told me that this derailleur may experience this type of problem with these shifters. According to them, the only shifters that are officially compatible with their "mountain" derailleur are the MTB trigger shifters. On an earlier conversation with a different Shimano rep, my bike shop guy was told that it's specifically the 971 derailleur that's having the problem, and earlier versions of the XT didn't have the issue. This is second hand, though, and I didn't get any more details about exactly which models would or wouldn't work. The guy I actually spoke to didn't tell me this, he just said flat out that mountain derailleurs won't work well with road shifters, period.

In any case, this was all a bit of a revelation to me, since I thought that 9-speed was 9-speed, I didn't realize there might be issues with mixing road shifters with mountain derailleurs. But there you go, two separate phone calls to different Shimano tech reps said pretty much the same thing.

But the thing is, I know that plenty of bikes are sold with this combination, so many people (most perhaps) never see this problem manifest... but I did (of course, if there's a potential problem then I'll probably see it). So it's just something to be aware of.

Incidentally, my "solution" was just to get a bit creative and go over to SRAM Gripshift + SRAM X.9 derailleur on the rear. It seems to shift correctly in all combinations, at least in the bike shop on the stand. I hacked some MTB bar end extensions to fit onto my drop bars, see the linked thread for details. I'll be testing the setup properly tomorrow.

Neil

Deanster04

I am using Dura Ace 9 spd bar ends with a mtb bike cassette 11-34 and the performance MTB derailluer without any problems...including a summer in the Alps: Austria, Julian, Dolomites, and sud triol. Another person on the ride used an SLX RD with the same cassette with no problems. There is a setup issue with the Barends where the last shift point 11 has a hitch that can be removed by someone who really knows the shifter can tune out. Once setup no shifting problems at all. I think the DT shifter has a positive stop and this problem may not occur. In any case It works for me.

BillyBob

Works for me on a trek 520. LX derailuer with dura ace down tube shifters.

gorshkov

Worked for me twice: once with LX, and once with Deore.

Bekologist

derailleurs are dumb, the indexing is all in the shifter.

I have seen bikes outfitted with STI and mountain rear derailleurs, and downtube and mountain derailleurs, and a whole heck of a lot of bikes with barends and mountain derailleurs.

Earlier this week I helped a woman set up her 10-speed STI bike with a new 10 speed 11-34 cassette and an SLX rear derailleur for lower gearing.

No problems!

Six jours

Thanks all. Sounds like excepting a bit of bad luck this should work.