My new cx/gravel build is 2x hydro ultegra shifter based. The ultegra front mech is bottom pull. The frame has a braze on for a pulley to deal with this but will any top pull front mech work (xt mtb double worked fine with 10 speed 105 brifters)- I will be using Middleburn cranks spiders and rings.

Assuming you are using a 46/36 chainset, and even more so if you are using smaller rings, it sounds like you should be looking at the top pull version of this:

http://www.chainreactioncycles.com/shimano-ultegra-cx70-2x10sp-band-on-front-mech/rp-prod70123

Is the CX70 designed to give better tyre clearance than a standard road front mech?

Is the CX70 designed to give better tyre clearance than a standard road front mech?

I don’t think it’s designed with the intention of giving better tyre clearance, rather to work better with smaller chainrings, like cyclocross chainsets, where the need to position the mech lower down the seat tube may result in a standard mech hitting the chainstay when changing to the small ring. I guess the design might possibly also result in better tyre clearance.

Couple of photos here of the mech (first one bottom pull version):

http://hubjub.co.uk/shimano-cx-70-front-mech-1922-p.asp

Shimano CX70 top-pull front derailleur

Thanks the photos are much better than the ones in the shop. It doesn’t look that much better than any other FD in terms of where the arm sits

aren’t the CX70 front mechs geared up for use with 10 speed?
11 speed uses a slightly different pull ratio.
Might need some fiddling.

The issue isn’t tyre clearance, but chainline but I’ve run up to 40mm tyres with a road chainset without problems – if the XT mech worked fine previously then don’t see an issue – why don’t you try it? Top pull is preferable for muddy conditions as pulley’s tend to cause more cable drag and cause mud to collect IME.

I’ve got an XTR FD-M961 front derailleur for triple for sale that can work either pulling from above or below. In good condition, not much used. PM if you want pictures.

Just use a pulley

^^^^ +1, just use the Ultegra setup the way it is. Tyre clearance can be limited, but not sure if that is your issue ?

Is the pull ratio going to be any different for the front mech? Would it matter if you used the above CX70 which is marked for 10speed – it will be on Middleburn 22/40 set up.

The pulley as a last resort but it looks like a bit of a bodge. It to go on one of these: