Wider gear ratio for 10 speed

MedsACG

I've got 10 speed dura ace 7800 with short cage mech running a 11 to 28 cassette, but want a lower gear so considering 12-32.
1.Will an Ultegra 6700 medium cage mech work with my 7800 shifters?

2. None of the internet retailers seem to have the 6700 mech (I realise 11 sp is standard now). Apart from ebay, any suggestions where a new one might be available?

dj58

Shimano only did a 12-30T in 10sp, CS-6700 or CS-4600, SRAM do a 12-32T in 10sp PG-1050. Both the SS and GS Ultegra RD-6700-A derailleurs are only rated for a 30T low sprocket however, you may be able to get them to work with a 32T sprocket with experimentation, B-Tension screw adjustment and longer chain.

viewtopic.php?f=40004&t=12952412

https://www.merlincycles.com/shimano-ul ... 56074.html

If you can't obtain a RD-6700-A then the alternative is the RD-5701 GS which is rated for a 32T low sprocket.
https://www.evanscycles.com/shimano-rd- ... r-EV177775

I can't see that they would not be compatible with your 7800 STI's, though I cannot find a compatibility chart showing those combinations.

Vino'sGhost

like wot dj said.

The alternative route would be to fit a mountain bike rear mech. Youd need a new chain but it should work. Ive got an XTR one here that was fitted to an older guys bike so he could still ride in the mountains without his knees hurting the next day.

craigus89

Or get the Tiagra 11-32 10 speed cassette, stick it on, tighten the B-screw and see how it goes? It'll likely be absolutely fine if you don't cross chain big to big.

http://www.wiggle.co.uk/shimano-tiagra- ... 0907659346

Yes it's heavier than the dura-ace, but if you're strong enough to need or notice the 100 grams saving then you wouldn't need the 32 tooth in the first place.

MedsACG

Thanks all, really useful advice.

svetty

Craigus89 wrote:

Or get the Tiagra 11-32 10 speed cassette, stick it on, tighten the B-screw and see how it goes? It'll likely be absolutely fine if you don't cross chain big to big.

http://www.wiggle.co.uk/shimano-tiagra- ... 0907659346

Yes it's heavier than the dura-ace, but if you're strong enough to need or notice the 100 grams saving then you wouldn't need the 32 tooth in the first place.

That might work with the 7900 series but is likely stretching things for the 7800. Granted if you avoid big:big it would be OK but I'm always wary of suggesting a combination that requires this as the cost of inadvertently shifting one cog too many and ripping off your hanger or worse is always there.

craigus89

Svetty wrote:

That might work with the 7900 series but is likely stretching things for the 7800. Granted if you avoid big:big it would be OK but I'm always wary of suggesting a combination that requires this as the cost of inadvertently shifting one cog too many and ripping off your hanger or worse is always there.

Fair point, I'm quick to suggest it but that's because I'm personally very conscious of my gearing and forget others may not be, I also love saving a quid or two!