[Closed] 42-30-20 cranks

as I want to run a 12-27 cassette

Been there, done that, found no matter what you need to change gear way too much on an MTB with a close ratio cassette. Fine for DH, but for XC the standard 11-32 9 speed is about spot on I reckon (well, unless you go 10spd with 11-36!).

One less ring, with a wider ratio cassette is the way forward IMO.

🙁
thanks. . . like the look of those really lightweight KCNC 12-27 cassettes. . . and losing that little bit up front with smaller rings. . . but the shifting issue makes sense.

Can get silly light wider range cassettes too if you shop about and don't mind spending mega bucks.

Losing a chainring up front is likely to save you more weight though. And constantly shifting to find the right gear was a PITA with a 12-27 on an XC bike.

Go 10spd, honestly! It's bloody ace... In fact, on one of my bikes I've gone 1x10 with a 32 ring up front, and 11-36 out back, and its pretty much all the gear ratios I ever need. Any lower than 32/36 and I just have to tell myself "get out the saddle, people ride up here on a singlespeed", and any taller than 32/11 and I'm spinning out going downhill on tarmac anyway.

KCNC do 11-32s too, and they're still crap. The alu sprockets are very fragile, prone to snapping. Buy one if you want to hang your bike on the scales, not if you wanna ride it.

mboy, what crank do use up front on the 1X10? I wonder what my gear ratios were on my 18 speed hardrock circa '89. . .

Just an XT, can use anything you want in a 1x10, just use an unramped chainring.

sram do an 11 - 28 road cassette.

The cassette isn't the issue though. To be honest I think it's a rubbish idea, unless you want to weigh your bike not ride it as I said.

I found a close ratio cassette of no real benefit on an MTB, but it does result in lots and lots of shifting on the front unnecessarily. YMMV of course.

You can get a Middleburn 5-bolt compact spider and the 58mm and 94mm rings for 20T, 30T and 42T. Remember Shimano front mechs like 12 teeth difference or they do not change to the larger ring easily.

I bought a few 20T granny rings from these guys recently...truly a bargain.

http://www.bikedock.com/home?page=shop.product_details&flypage=flypage-bd.tpl&product_id=1246&category_id=13

PaulD

i once had a 12 - 25 on my dh bike as it happens.

probably the worst decision ever.

it was essentially 9 versions of exactly the same gear.

And constantly shifting to find the right gear was a PITA with a 12-27 on an XC bike.

Why was say 32 x 16 more wrong more often than it would have been in the middle of a less closely spaced cassette?

Did the fact that there was another gear really close by make you think more often about whether you were in the perfect gear?

Middleburn is the way forward. 20 32 42 or 44 with an 11 32 and short cage rear mech at the back. In theory the short arm mech shouldn't really work but I find it works really well.

Think Surly used to do a chainset for the snow bikes on the Iditarod race. Called something like a Mr Whippy or Mr Whirly or something.

The closer spacing is partly what I'm after for cadences. but 12-25 would be too close I reckon.
this is helpful stuff, thanks

Called middleburn, guy was very helpful. Looks like I'm going to go for a two ring 26t - 39t up front. They don't do a 30t middle ring and very limited ring sizes for my XTR cranks anyway