I understand that the pull ratios are the same for shimano 10 speed road brifters and 9 speed mtb rear mechs, and this is sometimes used on CX / adventure bikes. I had thought this was to make use of the clutch in mtb mechs to prevent chain slap, but a bit of research suggests that clutch mechs weren’t available until 10 speed. Is this right?

If it is true, why do people do it, is it just to get a long cage option for 1x set ups? If it isn’t right, can anyone tell me which model numbers had a clutch? Cheers.

People have done this to use longer cage mtb mechs on road/cx/gravel bikes so they can use cassettes with lower low gears (bigger cogs). It will work with the older tier of 10 speed shifters (Ultegra 6700, 105 5600 and 5700, Tiagra 4600) but not new Tiagra 4700 as that uses the same pull ratio as newer 11 speed shifters. You can’t get a Shimano clutch mech below 10 speed and they’re not compatible with road shifters. But you can mod a non-clutch Shimano mech (MTB – Deore or above; road – Tiagra or above) by opening up the knuckle and putting the spring in a different hole to add tension to the derailleur. There’s a small hole on the knuckle which houses a bln hex bolt (2mm or 2.5mm I think).

Some 9spd mtb mechs are designed to work properly with 11-36t cassettes (road mechs aren’t).
We run 2 bikes like this, but the 10spd mtb cassettes seem to index better running a 1mm spacer between 3rd and 4th sprocket.

Thanks for the info, that clears it up for me.

Just about to do this myself. I’ve run a few 1x and it’s apparent that it’s the NW chainring that does most of the retention work, with a shortened chain.

Bear in mind that not all shimano 10 speed road stuff has the same pull ratio.

Recently changed from 10 speed 105 shifters which were around 9 years old (can’t remember the model number) to Tiagra 4700. Couldn’t work out why the existing 105 mech wouldn’t work, then realised the pull ratio is different so had to get a 4700 rear mech. Not sure which other group sets are the same…

[mick_r – Member
Some 9spd mtb mechs are designed to work properly with 11-36t cassettes (road mechs aren’t).
We run 2 bikes like this, but the 10spd mtb cassettes seem to index better running a 1mm spacer between 3rd and 4th sprocket.

Hi mick-r could you tell me more about that mode I have a 10 speed tiagra flat bar set up with 9 speed deore LC rear mech the shifting is perfect on the first 7 cogs but not so good on the bigest 3 especially shifting down to the smaller, the cassette is sram 12/36 can i mod this the smae way do you know?

Some 9spd mtb mechs are designed to work properly with 11-36t cassettes (road mechs aren’t).
We run 2 bikes like this, but the 10spd mtb cassettes seem to index better running a 1mm spacer between 3rd and 4th sprocket.

Wow interesting and maybe explains why my Fargo with this set up doesnt fully index correctly. Odd though as the identical set up on my Tripster is fine so I thought something was slightly bent on the fargo (mech or alternator drop out).

I never found a full explanation. Initially I thought it was the 1mm difference road vs mtb 10spd cassettes. But a road cassette had the same issue.

Machinist at work made me a 1mm spacer. On xt cassette it goes between the main sprockets and the biggest 3 on spider. Looks slightly odd but indexes perfectly.

We run the tiagra 10 shifters with external cable and barrel adjuster (not under tape) as they are easier for CX friendly cable lube and don’t need unreliable in line adjuster (no barrel adjuster on mtb mechs)

Deore m592 shadow rear mech. Hope this helps!

It’s because the Tiagra shifters pull different amounts of cable to other road 10 speed shifters (assuming 4700 series) as above. If you use a 4700 series rear mech it will work perfectly without the spacer. But then you won’t have the clutch.

Been using an old xtr 9 speed medium cage with 10 speed STIs, narrow-wide ring and 11 – 40 cassette with no problems.

Bought a jtex shiftmate thingy to allow for use with a clutch mech after discussion on the ‘tanpan thread’ and realised I was looking for a solution to a problem that didn’t exist!

It is worth mentioning that the new 4700 Tiagra mech’ is rated to 34 teeth.

So I’m assuming that it should be OK 36 teeth. Given that people seem to be able to get 105 rear mechs that are rated to 32 teeth are running 36 teeth cassettes. Infact spec’ even sell a bike with a 105 mech’ and a 36 tooth MTB cassette

Well that explains why the indexing was screwy 🙂

Did shimano really need to invent yet another 10 speed cable pull standard?….

Ok I fixed mine with a new mech hanger the old one had a very slight twist only visable when removed and lying on a glas plate.

Did shimano really need to invent yet another 10 speed cable pull standard?….

It’s the same as 11 speed Shimano road, but the levers have one less click. It means you can run an 11 speed 105, Ultegra or Dura-Ace rear mech with your 4700 levers. or conversely a 4700 rear mech with 11 speed levers.