Tech docs say 27 is max, but general consensus online seems to think that is a conservative estimate.
Anyone actually tried it and did it work. Can't justify/be fussed spending big bucks on a compact right now, so trying to get squeeze additional ratios from the cassette.
Mech is a Ultegra 6600, think its the standard ss model, although it doesn't state this on it.
ta
Just wind the B-tension screw in.I tend to view shimano's listed capacities as 'guidelines' 😉
Yep, 28 is fine.
so how big do you reckon I could go? I notice they sell them in 30s as well!
Pushing it? or will it work if I jiggle with the limit screws?
ta
I run a 32 as an off-road alternative on my Frankenbike. No mech/spoke interface yet - just avoid shifting too low down the block when you're in the big ring.
Edit : Same mech BTW, with a 53-39 CS
web wisdom says 28 is max. apparently its the fact that the mech can't clear the cassette. is your mech 6600ss teasel? I'm tempted to give it a go but can't be assed ending up with a 50 quid cassette I can't use.
and what happens when you do shift to far down the block in big ring?
and what happens when you do shift to far down the block in big ring?
Dunno, but I imagine it wouldn't be pretty.
I'll take pic tomorrow in the the lowest gear so you can see the set-up for yourself. Watch this space...
I think it's the overall capacity you have to watch for.
The 6600 is 29 teeth IIRC, so your front teeth difference is 14 (53-39) and your rear 16 (28-12?) so your total capacity is 30 so only 1 over?
I had a problem recently when I tried to put a 11-28 with a 50-34, total capacity was 33 and the mech couldn't take up the slack in the chain when on small chainring and small end of the cassette 🙁
Okay - as promised, here are the pics. A 6600 mech with a 32t block. No shifting issues whatsoever. No dropped chain, either.
39t chainring...
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53t chainring...
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Just fitted one to my roadie tonite, seems fine. Granted I left the chain a link too long, but that's easy to sort.
Shifts up & down the block easily with a short 105 mech on 50/34 front.
thanks teasel, is that defo the ss verion of the mech? Steve, what mech were you running? Is it a 30 tooth you fitted?
may give it a go...it appears to work.
is that defo the ss verion of the mech?
Yessum
As far as I know it's the SS mech, I've fitted a 28t but don't see any reason why a 39t won't fit
there is no universal answer because dropout lengths are, surprisingly, not all the same.
28 is usually doable though, with a tension-screw tweak, but any more teeth is pushing it. Some people get 30t+ without jockey rubbing but I've had frames where 27t is close. Chain length helps obviously, as a short chain pulls the mech arm forward, freeing up more clearance.
The newer mechs (6700, 7900 etc.) have more clearance so are officially good for 28t.
Tick
Reggiegasket is right. For example, at the 3 Peaks, I used a 12-36 cassette with 39/46 rings and a 6700 rear mech. No problems at all. I must have an extraordinarily long hanger. If you'll pardon the expression.
If you have trouble clearing the bottom gear, say when maxing it out to 32, you can get a 10t pulley top cog to replace the stock 11t one.
With some care about the chain length it should work. Big-front to big-rear is not a gear you want to run a lot anyway.