Road mechs on MTBs

[jimo746]

I used a drilled out Ultegra 600 rear mech fir a while in the early 90's, think I'd seen a Pro doing similar in a magazine and followed suit
It was ok, worked about as well as a MTB rear mech as I remember, collected mud more though.

 

[frkl]

I used a drilled out Ultegra 600 rear mech fir a while in the early 90's, think I'd seen a Pro doing similar in a magazine and followed suit
It was ok, worked about as well as a MTB rear mech as I remember, collected mud more though.

Oh no, something new I need to try.

Just a note that I have a 600 Ultegra RD 6401 shifting up to a 32 teeth cog without modification or using a hanger extension--I need a really low gear on my road bike where I live. It works just fine, despite being rated to only 28 teeth.

 

[hamster]

A lot of the max cog size depends on the length of drop on the gear hanger. Shimano always errs on the side of caution and it's guaranteed to work inside their limits. Normally there is some extra leeway.

Back to the original question, happily running an M735 short cage on an 11-30 with 34/44 chainset. I always keep big-big available, it's always when tired or distracted that I cross-chain. I'd rather not blow up the rear wheel by having a chain too short.

 

[dirttorpedo]

I remember seeing people do this BITD and thinking they were nuts, but every vintage 7 speed I've picked up over the last bit had a 28 tooth low gear so its probably not a big deal. Particularly if you were using a microdrive crank. I'm surprised it would lock up though - I ran a 27x50 on my modern road bike and never had an issue with the short cage ultegra.

 

[rogerzilla]

I used to run a 1055 rear mech (the one with the funky "aero" cage, like Ultegra 6401) with 46/36/24 and 13-30.

 

[minor_LEGEND]

This trend swept through our riding clan back in the 90's, when I approached my LBS for an Ultegra rear mech he insisted I bought a certain variant of the mech to work on my DX equipped bike.

 

[Fatal Swan]

And not just on retrobikes... I'm running a Dura Ace 7900 short cage rear mech on a 3 x 9 XTR M960/970 setup. The M960 chainset has a 22t granny ring, so there's no way I need a larger sprocket than 27, which means I can use a nice light 11-27 Dura Ace cassette (175g) and keep the cassette ratio close. I did try the mid cage XTR rear mech but the short cage Dura Ace works better with the close ratio, and is also lighter at 165g. The chain is sized to make sure big-to-big doesn't snap, and while it's definitely a bit slack on the smallest few sprockets when using the granny ring, that combination has no real use anyway.

 

[rigidftw]

And not just on retrobikes... I'm running a Dura Ace 7900 short cage rear mech on a 3 x 9 XTR M960/970 setup. The M960 chainset has a 22t granny ring, so there's no way I need a larger sprocket than 27, which means I can use a nice light 11-27 Dura Ace cassette (175g) and keep the cassette ratio close. I did try the mid cage XTR rear mech but the short cage Dura Ace works better with the close ratio, and is also lighter at 165g. The chain is sized to make sure big-to-big doesn't snap, and while it's definitely a bit slack on the smallest few sprockets when using the granny ring, that combination has no real use anyway.

I‘d like to see some photos of that setup!

 

[KermitGKona88]

I used to run a 1055 rear mech (the one with the funky "aero" cage, like Ultegra 6401) with 46/36/24 and 13-30.

I used to run exactly the same setup worked brilliantly, and as LGF I swapped road cages on MTB mechs for years and still do...

 

[Fatal Swan]

I‘d like to see some photos of that setup!

Here you go https://www.retrobike.co.uk/threads/cannondale-scalpel-sub-20lb-full-sus-26er-build.427637/