Bicycle Mechanics - How to get the lowest gears possible?

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erbfarm
05-29-08, 07:46 AM
I live in a very hilly area, there is no flat ground to ride on and the hills are *very* steep. My triple 48-38-28 is way too big for my use. I never use the big chain ring. I use the 38 a little but spend most of my time on the 28 (with a 34t in the back). My question: I'm thinking about getting the Sugino Impel triple which has 42-34-24t rings (I wanted the 42-32-22 version but it only comes in size 175mm and the 650B wheels on my early 80's Specialized Sequoia frame won't allow anything longer than the 170mm cranks I have now). Is the 42-34-24 the lowest gear combo possible for me? Or should I just strip off the 48t on my current cranks and replace the 28t with a 24t and ride a double? If so, how would I know what size Bb to use? Thanks for the info!

Maria


Little Darwin
05-29-08, 08:54 AM
You need to get yourself into a bike shop and not just looking online...

Chainrings can be purchased to customize things in a lot of ways. I don't know your current crank, but unless it is the type with chainrings rivetted in place, you can theoretically run a 42-32-22 on your current crank simply by replacing the chainrings.

dobber
05-29-08, 09:24 AM
You could always get goofy and go quad

http://www.abundantadventures.com/quads.html


Joshua A.C. New
05-29-08, 12:41 PM
I suggest an 23-tooth granny gear to a 23-tooth Sturmey-Archer hub in low gear. That gives you a ratio of 3:1.

Good luck staying upright.

(I'm joking, of course, but I just realized that that setup would give you a huge range for three speeds: 3:1, 1:1, 1:3. Huh. It might make sense to approximate that. So, yeah, go visit a local store and see what they advise, since they know the local terrain better than anyone on the Internet.)

HillRider
05-29-08, 03:34 PM
I suggest an 23-tooth granny gear to a 23-tooth Sturmey-Archer hub in low gear. That gives you a ratio of 3:1.
It will also probably shatter the planetary gears. Most internal gear hubs have a specified minimum chainring/cog gear ratio to keep the torque load on the internal gears load within the design limits.

To the OP: an MTB crank with 22/32/42 or 44T chainrings will give you as low a ratio as is feasible with a 12x34 or 11x34 cassette. Many of the Shimano MTB cranks (Deore XT and LX for example) are available with 170 mm arms.

DDYTDY
05-29-08, 07:54 PM
TA Carmina Triple cranks with a 94/58 mm bolt circle. You can get as low as a 20T chainring with that set up. Crank arm lengths from 155mm to 185mm.
Lots of $$ though

DDYTDY
05-29-08, 07:55 PM
Or NOS Suntour Micro Drive?