Gearing ratio's and crank length questions

mfereborn

Right guys, im running XT hollowtech 2 cranks on my bike with a 44t outer ring. I often find myself outpacing this ring on road especially but sometimes also on trails (rare) is it worthwhile me putting up with it or would it be worth sourcing a 45 or 46teeth ring for the outer.

Furthermore, would a longer crank allow me more torque, and other than clearance issues would there be a downside?

louse

Yes you will run out of gears with that one the road which is why the touring version have a bigger set of cogs with the big cog being 48t.
Many people find 44 to much for off road and manage fine with the 32 and a bash and just don't pedal as madly when decending.

mfereborn

Maybe i'm just being too balsy then :P

i'll look into a chainring one or two teeth bigger, i think 48 would be much too excessive for the MTB regardless of where i am!

mrmonkfinger

what cassette do you have?

mfereborn

i think its a 9 speed pg970

Chunkers1980

2 teeth extra over 44 is only 4.5% bigger. Not really worth the cash. Much better to make sure you've got 11 and 12 t on the rear. Clearance is a factor too. PS do you know an outer XT ring is over 70 quid? If you're still keen try finding a cassette that has 9 or 10t

nicklouse

Chunkers1980 wrote:

If you're still keen try finding a cassette that has 9 or 10t

none that fit standard hubs.

mfereborn

cheers guys, cost doesnt bother me as i likely wont be going XT rings anyway, i feel there must be better quality for less money somewhere - also XT rings dont appear to come in the sizes im after. and 4.5% bigger sound like a hell of a difference to me?

386ka

My Trance has a high gear of 44t front and 11t back, and, I have never, never run out of speed on the road. What is your smallest cog on the cassete?

The Rookie

mfereborn wrote:

4.5% bigger sound like a hell of a difference to me?

The difference between most gears on the cassette is around 10%, so it's only half a gear bigger.

Simon

mfereborn

my highest gear is 44-11 and im out pedalling this on the flat (like i said, rarely but often enough to annoy me)

bails87

Isn't that like 30mph+.......on the flat.....on a full sus MTB? :shock:

mfereborn

Even i myself am doubting what im saying thinking this...

i certainly dont think im doing 30+ as im sure a road bike would struggle that!

Somethings a miss here

bails87

Well I hit over 30mph on my Boardman, that had a triple (22-32-44) and an 11-32 cassette. I wasn't spinning out. We might have different definitions of 'spinning out' though

I've hit 40mph on my road bike BTW, and if I try there's a few not-too-major hills that I can hit 30 on, but that's on a road bike, and when I've done them on an MTB, again, I havent spun out.

The Rookie

At a cadance of 90rpm, 42/11 and 26" wheels is about 21mph, 120rpm is 28mph.

I've hit 26mph on 32/11 (about 150rpm), the single speeder on the ride was hitting nearly 200rpm, but wanted to slow down for a drink (sake, brand by the name of lux I think he said........)

I really can't see you spinning out 42/11 off road, or even on road with an MTB, I don't spin out my Hybrid commuter with 46/11 at a GPS logged 40mph (Downhill, I'm not superhuman).

Simon

njee20

Yep, 44/11 at 100rpm (which is a pretty modest cadence) is 30.9mph. Doubt you're spinning out regularly on the flat, descending maybe, but do you really need to be able to pedal quicker than that and potentially compromise elsewhere?

386ka

Also, be aware that a bigger ring will decrease off-road clearance. PS, a bigger crank will allow you a greater torque, but you have problem with RPM, not torque.