Singlespeed & Fixed Gear - Uphill/Downhill/Flat Flip-flop gearing?
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08-21-07, 09:58 PM
Okay, I've just gotten my Jamie Roy with 46x17 fixed gearing. I've got the other side to spare and so far in my riding, I've noticed I've been going slower on flat roads and trying to go any faster only tires out my legs.
Another thing is I do a lot of my group rides on hills in the 7-10% grade range and I'm positive I won't be able to last with a 46x17fg uphill or downhill.
So I'm thinking I'll make it 46x14 SS or something for downhill/flats and 46x22 for hills.
My question is...is that too much of a change in teeth for one chain?
Also, does that make much of a difference?
08-21-07, 10:14 PM
yes, 8 teeth is too much. 46x22? that's 54 gear inches... don't know anybody that rides that small, even ken cox. 46x18 and 46x15 would be more ideal. you don't really want to dip below 60" unless you love to spin absurdly high RPMS or go very slow.
08-21-07, 10:16 PM
Yeah it did sound a bit absurd. so x18 fg and x15 ss
08-21-07, 10:21 PM
sure you don't want the ss for up/down hill and the fixed at a higher ratio for the flats?
you don't want to be spinning downhill.
and you don't want to be switching ratios that often. i ride 66 g/i SS and 68 g/i fixed. one tooth difference.
08-21-07, 10:29 PM
Yeah I reasoned that out wrong, I meant it the other way around.
so x18 ss for up/downhill and x15 fg flats. considering my 17 gear right now, will I have to switch out my chain? (the lugs sit all the way at the front of the track ends right now). Also, will a few gears make that much difference?
The reason why i ask all these questions is because I'm considering selling my geared Marin that I use as a grocery getter/mule and instead just muling stuff in my backpack (or use the existing rack from my Marin)
08-22-07, 01:11 AM
you may just be able to get by with a four teeth difference in the cogs, which is two chain links at the track ends because the chain is doubled. a three tooth difference is better as you're more likely to be able to get enough of the axle bolts biting on the track ends. adjust the number of links in your chain so that when its on the bigger gear (ie the 18tooth SS cog) it is hard up as far as it can get into the track ends. then when you put the fixed cog on (15 tooth) you still have enough room behind the axle to move it back to get correct chain tension. remember to run TWO brakes if you SS. 46:18 is still a tough gear for lots of hills, but 46:15 is pretty good for 20mph plus on the flat. I don't know what hils you have there, but 42:16 is about as much as i can run here on mostly 8-12% grades without stuffing my knees. i can do 15% grades too, but that's like a weight training session.
if you ride with a heavy rear rack it'll be harder to skidstop. backpacks are easier to carry around, too, when you're off the bike, but your back sweats. life is always a tradeoff.
08-22-07, 01:17 AM
I don't ride with the rack when I ride hills. I do have dual brakes on my Jamie Roy so I'm okay in that department. The steepest grades around here are about 10% but I am a novice (only about 6mnths of serious bicycling under my belt). I still havn't learned to skid-stop as I'm riding on platforms.
And I'm going to stop by my LBS to see what they can do for my gears. The last time I was in there he told me a freewheel's about $20. How much do fixed cogs usually run? I'm also going to pick up some cheap tugs from him as I've yet to take off my rear wheel (only had the bike for 3 days).
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