ok, I'll be getting me mits on a new Alfine hub tomorrow. Will be just a collection of bits for a few months whilst I wait with anticipation for my new frame (Singular Swift 29er) Lots of new Hope bits knocking around, and as said the Hub will be here tomorrow... Question.. I want to be able to replicate my granny gearing... which begs the question-
What ratio do I need if I run a 32T ring up front?- not worried about the fact I'm on big wheels, would just like to get it to what I'm used to.. so 32x? equals my granny gearing of 22X34?
try this calculator......also figures out for IGH
Sheldon Brown's Bicycle Gear Calculator
Sheldon Brown's Internal Gear Calculator
The lowest commonly available cog for the Alfine is a 22t. The lowest gear ratio on the Alfine is 0.527. So basically whatever your gear ratio is, you multiply it by 0.527 to get the ratio in 1st gear. So with a 32 ring in front and a 22t cog in back, you have a ratio of 1.455 multiply by 0.527 equals 0.766.
Originally Posted by ratty2k
Your current granny gear is 22/34 for a ratio of 0.647.
So basically, with a 32t chainring you cannot get as low as your current granny. 32/22 on the Alfine would be very close to your second lowest gear. which is 22/30=0.733.
So you basically have 3 options: get a larger cog, a smaller chainring, or live with the current ratio. I was able to find a 24t cog from a shop in the UK, which will lower it a little to 0.703. You could go with a 30t chainring, which would give you a ratio of 0.719, or you could combine the 30t ring and 24t cog for a ratio of 0.659, which is just about the same as your current granny. Keep in mind, that the lower you go, you will also be lowering your high gear as well. The highest gear on the Alfine is 1.615 times your ratio. So for the 30/24 example, your high ratio will be 2.02. For comparison, middle ring small cog on a 3x9 equals a ratio of (32/12) 2.66. Your high gear on the above 30/24 setup would be egaul to 32/16 on a regular setup. Whether or not that is fast enough for you, I do not know.
My suggestion would be to start with a 32t ring and a 22t cog. Give yourself at least a couple of weeks to acclimate to the new gearing before deciding if you like it or not. You 'should' find the super low granny is not really needed. You will work a little harder on the really steep stuff, but you will get up faster! If you live in the mountains or something, and really need the super low gearing, than go with the 30x24 and give up some on the top end.
I am currently using 34x24 on my Alfine and it works fine. I searched for quite a while to find the 24t cog. My reason was that I switch my bike from singlespeed mode to Alfine, and my SS gear ratio is 34x24. So I can swap wheels without having to adjust chain tension.
Keep us updated on the build, and good luck!
Thanks for that, been looking at the gear inches side of things as a comparison. But that explains it better, cheers!
Have gone for a 32x 22 setup and have been deliberately trying to use higher gears than normal on the last couple of rides to see what it feels like. Will be doing just what you suggest tho and staying that way for a little while. SJ cycles for the sprocket? (24T) its all I can find- but I reckon my LBS could get one for me if need be.
Really looking forward to the new bike, pity I have to wait till mid June for everything to arrive/ be built. Never mind, still got other bikes to enjoy!
Alfine for Granny
I just laced up an Alfine (SGS501) hub for my Karate Monkey ... WOW!!!
It came with a 19 tooth cog (and I have a 32t crank), which wasn't geared quite low enough for the kind of riding and climbing I like to do. I found a 23 tooth cog from Harris Cyclery (which is the lowest I could find, and is pushing close to the limit, according to Shimano).I installed it Monday night and took it out last night for a test thrashing.... The granny felt about the same as my derailleured granny... It climbed AWESOME!!! As long as your not shifting ham-fisted, the shifts are super smooth. The best part is I can swap out this wheel with my SS hub in 5 minutes... I fear my Niner MCR will get less riding time... The Alfine (finally) may be the real deal!!!
I should check this forum a bit more often! Thanks for that, looking probably at fitting a 22T on the back. Think its a 20T at the moment. Ecuse the not quite sureness... the new bike is still a pile of bits, some at my house, some at the LBS and some on order- rims and frame....
My Alfine came today!!! Yay! But man o man, it's a heavy little sucker! Most importantly my 140 mm XTR rotor and caliper have more than adequate clearance. I was a trifle worried despite a few reassurances. All the pictures looked way too close for comfort. Now to get my wheels laced!
[QUOTE=dru]My Alfine came today!!! Yay! But man o man, it's a heavy little sucker! /QUOTE]
You'll hardly notice the weight once it's rolling... The Alfine is much lighter than the SRAM i-Motion-9, almost a pound (400 g) lighter...