whobiggs

I have just tried to fit a shadow rear mech with 105 shifters to suit a 12-36 cassette and found they have changed the pull ratio. Is there another 10 speed rear mech I can use?

rdtompki

I don't think you want a 10-spd RD. The 9-spd RD have the correct pull ratio. My wife has 105 on her single with an 11-36 10-spd cassette and a Deore RD

MNRon

This is spoke for truth... The RD should be a 9spd for the 105 shifters.

DCB0

Yes. 7, 8, and 9 speed MTB rear Shimano derailleurs work with 10 speed road shifters and cassettes. The newer 'Dyna-Sys' rear derauilleurs will not work with road shifters, only with the 'Dyna-Sys' mtb shifters.

alex jb

An Ultegra 6600 GS (med cage) would work also, I use one on a 10sp with 32t large cog.

shelbyfv

You may also want to avoid the Shadow models. My understanding is they may work, but the others work better.

FastJake

With a 36T cog? Doubt it, I'd just get a MTB RD.

+1 Any non-DynaSys Shimano MTB RD will work, like a 9-speed Deore, LX, XT, XTR, etc.

alex jb

I stand corrected.
It does work with a 28 and a 32 though.

cyclist2000

I have a 9 speed rear xt with 105 10 speed shifters on my touring bike, works fine.

Jed19

Are you telling me that your Ultegra 6600 (medium cage) can do a 32t on your bike without issue(s)?

well biked

It's not uncommon, there's a lot of leeway depending primarily on the derailleur hanger's orientation relative to the rear axle. There's certainly no guarantee it will work, but it might; and there's a possibility it will work, but not well.

One of the most common mistakes on this forum is when folks post definitively about a rear derailleur working with a largest cog that's well beyond the derailleur's stated spec. Folks need to understand that it might work, it might not. Trying it on a particular bike is the only way to know for sure. I've seen bikes with 27t largest cogs equipped with Shimano road derailleurs rated for a 27t largest cog, and the upper derailleur pulley hits the largest cog unacceptably even when the b screw is screwed all the way in. Bottom line: the results will vary from one bike to another.

whobiggs

You are right, I have just tried a 9sp Shadow and it almost works. I can get it working fairly well but I think once it wears a bit it will be a constant fiddling nightmare to keep it so.

whobiggs

You are right, I have just tried a 9sp Shadow and it almost works. I can get it working fairly well but I think once it wears a bit it will be a constant fiddling nightmare to keep it so.

Papa Ado

Shimano recommends Shadow RD's for 12-36 (HG61):
M772 Deore XT 9
M662 SLX 9
M592 Deore 9
M810 Saint 9

rosswog

Shadow rear derailleurs don't have a barrel adjuster, which is necessary to set the shift cable tension when used with 10 speed road shifters.

I currently have 105 5700 10 speed shifters, XT 772 9 speed rear derailleur, and SRAM pg1070 12-36 10 speed cassette on my bike and its been a nightmare to keep tuned. There's no proper barrel adjuster in the system, so I'm using an inline cable adjuster ahead of the downtube cable stop, and in my opinion - it's no permanent fix. I also believe the direct cable routing causes an issue too, because shift cable tension is too loose in high gears (12t) and too tight in low gears (32t/36t). Not to mention the fact that the cable / housing wants to sit right over the skewer and makes it difficult to remove the rear wheel or mount the bike on a trainer.

The deore m591 rear derailleur looks like it has a barrel adjuster on it, and uses the traditional loop / bend in the cable housing - I am most likely going to order on and see if it works better.

oldbobcat

Thanks for explaining this so well. I've been getting tired of doing it and getting a lot of dumb looks from people who should know better.

All a GS road derailleur does is change the capacity to pull tension on slack chain, as in a triple application. It does not change distance between the jockey pulley and the largest cog.

alex jb

Yes my Planet X Kaffenback with a 6600GS happily runs a 32t top gear on my dirt wheels.
I went with a GS more to deal with the tension change between the lower gears in the 34 small front ring and the second cassette gear 29/50 chain ring combo.
i do have the B screw 3/4 way in, but could also be the relative position of the axle/derailleur on Planet X's replaceable dropouts.