Shimano dyna sys compatibility.
 

Hi folks,

I'm in the process of collecting parts to update MTB drive train from 1 x 9 to 10sp.

I have several 10sp cassettes for my TT and road/commute bike, the big ones I have are a 11-28 and a 12-30 and I would like to have interchangeability as I'm considering going from 2x10 to 1x10 on the commuter. It has ultegra GS rear mech so hopefully will handle a 11-34.

I read on Shimano's site that dyna sys is 'not compatible with 10 sp road chains' is this actually true or is it just trying to seperate road and dirt?

The MTB wheel goes in the commuter, same 160mm rotor, 1.95 tire clears, but will the chain chew the cassette or vice versa?

Your Ultegra rear derailleur won't handle a 34T large cog no matter what the cage length. Ultegra rear derailleurs are rated to handle a 27 or 28T maximum cog. This limit can be exceeded slightly but not as far as a 34T cog. You need a MTB rear derailleur and it must be 9-speed or earlier to work with 10-speed road shifters.

Dyna sys rear derailleurs are not compatible with 10-speed road shifters but I've never heard they require a specific chain.

the road and mountain chains are different. they will probably work but shimano would call it a "B" fit

Only when running 57/67/7900 double, and then only when using Shimano symmetrical chains, this was never an issue for triple groups, and has been dropped for 11 speed.

For the RD, a GS will take upto a 32t with the B screw filpped backwards (I have used this setup for the last 2 years), but going to a 34t will be pushing it, an alternate option would be to use a Deore 9 speed RD, not tried this, but this is a common suggestion when the question of running large cassettes with 10 speed road is asked

Ok, seems like I may need to leave them seperate.
I regularly run the 12-30 cassette with the Ultegra and it is fine, B screw a fair way in to throw its position back.

Because my commuter (Planet X Kaffenback) can only clear a 35 tire on a 700c rim, I tried my 26" MTB wheel in there with the 1.95 tire and it clears fine.
I'm wanting to use this bike on the canal tow paths and when the weather is like it is now, a CX 35 tire is a bit narrow.
throwing the MTB wheel in is quick, changing cassettes is more trouble than I wanted to go to each time.

Oh, and 34 is the smallest I wanted to go with the top gear on the MTB cassette as I make the upgrade to 10sp, as I run a 34T ring at the front.

Unless you have disc brakes, this wheel size change won't work. A 26" (ISO 559) rim will be over 31 mm (1/1/4") lower than the 700c (ISO 622) rim and no rims brake will adjust that far.

Got to ask, how much does sticking 26" wheels in the Kaffenback affect it, looking at mine, it would bring the BB down far to low.

For the brakes, take it that alex jb as a MK2 which has disc mounts

Correct.
swapout dropouts with disc mount.
Wheels are 24mm wide rims so can run a skinny 25/28mm road tire if I fancy, but I'm more going for the monster cross build.
Avid BB road calipers work great from the ultegra Brifters.

as for the BB height, I only had the 26er wheel in there for a looksee, leaving the 29er up front it didn't look too low, not that I'm going to need massive clearance for canal tow paths.

a dyna sys chain is not the same as any road chain. the profiling is different