Are Deore trekking / MTB groupsets compatible with cyclocross frames for touring conversion?

Question

I have a pre-disc-brake vintage 10 speed cyclocross bike that has already seen me through some tours, however, I find the compact chainring is sometimes not geared low enough. I'm also growing increasingly frustrated with the lack of support for 10 speed shifters / components now that Shimano's road components have moved-on... I've previously converted from drop bars to flat bars.

It seems like the "trekking" T6000 and T8000 groupsets might be worth considering, but they are hard to find, and appear to be slightly modified versions of the M series mountain versions.

I'm curious if touring cyclists have had much luck finding and using the T6000 or T8000 series components on road frames, or else the M6000 / M8000 mountain bike equivalents. Any issues with compatibility?

Answer 1

Some general rules of thumb:

The front crank does not care how many speeds are in the back. 9-10-11 speed chains all have the same internal width, it is the external width that is different. Using a 10 or 11 speed crank with 9 speed chain and vice versa provides acceptable performance in my experience.

I have had very good luck using deore XT 10 and 11 speed cranks with 9 speed gearing. The one caveat is that the chainline for road and mtb is slightly different. MTB axles are wider.

The really hard part is finding an appropriate shifter/derailluer combo to shift an MTB triple. If you are currently running a compact crankset, then keeping your current derailluer/shifter and switching to an MTB crankset should be a workable solution, provided you can lower your current derailluer enough to match the outer chainring. You might also need to grind the derailluer cage a bit to match the curvature of the outer chainring.

The thing to keep in mind is that everyone has a different definition of "works". The more you stray from shimano's recommended configuration, the less guarantee of flawless shifting. Only you can decide if it's good enough. I'm sure that there are people that would find the bikes I build and ride completely usable.

My 2 cents:

If money isn't a limiting factor, I would seriously consider switching to an 11 speed MTB 11-40 cassette in the back and a double chainring in the front. With the explosion in gravel bikes, support for this setup is increasing. Shimano MTB 11 speed will work on any older shimano 9 speed or greater capable freehub.

There are also conversion kits that allow you to add a 40t cog to an existing 10spd cassette. With add-ons like the Wolftooth road-link, you can shift these cassettes with current long cage road derailluers.

Answer 2

Presumably you're saying you have the bike set up now with 2x10 Shimano flatbar road shifters, so the left shifter along with the FD will need to change regardless if you get a trekking triple type crank. It's not clear what you're asking and whether or not you're starting from the place of planning on getting a compatible shifter and trekking FD to go along with the new crank.

Shimano road triple front derailers and shifters do tend to work fine with their 48/36/26 trekking cranks. It pushes slightly past the 20t total capacity of most or all contemporary ones, with the effect of causing rub on the bottom of the FD cage in the cross gears. But the only reason to do that would be creating an aesthetic or tactile match with the existing right shifter. The correct left shifter and FD combination would be any triple or triple-compatible shifter plus FD-T6000, FD-T8000, etc. Performance will be better that way.

What doesn't work with the trekking cranks are normal mountain FDs with any shifter, or trekking FDs with road shifters, or road triple FDs with mountain shifters.

That said, there's not much reason to not just use a left friction thumbshifter, which eliminates any finickiness with getting the adjustment just right on a setup that's not really made to be compatible. For touring in particular this keeps things way simpler and more reliable.

It's possible to encounter clearance issues when adding a triple to any bike, although it's not particularly likely here with the 26t ring in question. If you wanted to mitigate that risk you could get a similar crank in square taper, allowing you to dial in your spindle length, although that can only be pushed so far before chainline takes a hit.