Singlespeed & Fixed Gear - 48/12, too hard on road?

165cm crankarm length. Calculation from Brown: gain ratio 8.1!
Is it too hard for errand running/touring/commute?

errand running: good workout

touring: farewell kneecaps, we barely knew ye

Why don't you try it out and let us know.

yeah, unless your nickname in high school was "the hulk". i used to have 48-16 and went down to 46-16. maybe if you raced track all the time you'd want that on a longer distance bike, but for groceries/errands where you're stopping/starting all the time it would be borderline ridiculous. at least for me.

OH NOES (http://www.sportsinjuryclinic.net/cybertherapist/front/knee/anteriorcruciate.htm)

That's like 108 gear inches. You'd be doing 29mph @ 90 rpm. Anything below, goodbye knees.

put a 16/17 cog on

Get on a geared bike and put it in 52/13, that's the same gear inches (105.1). If that's how hard you want to push all the time, go for it. If you're like me and that's a gear you might hit up on a downhill or with a stiff tailwind, go for something more sane like 48/17. Tall gearing sucks around town, you can't accelerate fast enough to keep the cars behind you.

I use 52/17 on a 165 crank, for errands all the time with panniers and whatnot.
It's a 52 biopace though so the power part of my stroke is more like a 50. It's a multi speed bike but I have downtube shifters and tend to just leave it in a gear.

Are you going to ride fixed? 4:1 ratio will be hard on your tire. Consider 48x11 or 48x13 instead.

I'm running a 52-18.

I havent had much time to rid ethough, is that to high, could I possibly hurt myself (knees) with it?

52/18 is doable. If you have to go up many hills, you might find it a bit hard. I draw the line at a gear ratio of 3. Anything bigger than this is going to suck on the street unless you're really strong. As it is, I'm running 48/17 and I want to drop down to a 46t chainring. I just can't keep up a good spin and I feel inefficient.

jesus, unless you're the hulk don't bother. I'm not the strongest mind you, but i'm pushing 48X16 in new york city (around 81 to 82 inches on 27 by 1 and 1/4 tires) and it's a little overboard with steep bridge climbs (at least i'm not the only person gearing down due to wburg bridge nside ped walk closing...). I had my bike converted and that's the gear they put on there and I just thought I was a ***** bc I couldn't spin it (bc I didn't know any better). I made myself get used to it and I'm definitely very much stronger for my effort, but I'm dropping about 7 to 9 gear inches on my new bike to learn to spin a bit better and be more efficient (and build my stamina). Currently even on bridge descents I feel I've got a little bit of gear left to push, and I don't feel the speeds I can hit on a rare long, uninterrrupted flat are worth the loss in acceleration. unless you live on a prairie and there's very little or no stopping, or you're some track hero looking for your first street bike, you're just gonna kill your knees and possibly yourself. can't tell you how many times in the beginning i pulled out to try to make it bt some oncoming cars only to realize i wasn't going anywhere and almost getting hit...

Also, if you're planning on being brakeless or emergency situation braking only, 4:1 is going to make it tough to skid/skip. Remember, when the wheel is trying to turn your legs it gets the inverse of the gear ratio.

I was riding 48x15 for a while, and it killed my knees and made skidding a pain. You're not going to impress anyone with that crazy ratio, go with something more reasonable (16 or 17).

im runnin 48x14 for over a year....its fairly ok on the street except it's takin it's toll on my right knee but i've always had problems with that,its definatly possible tho, had a friend with 52xsome crazy **** and he seemed ok aswel...

yea thats good for going downhill everywhere you go on streets with no intersections

You're not going to impress anyone with that crazy ratio, go with something more reasonable (16 or 17).
Actually, anything more than crawling with that ratio would impress me.

Actually, anything more than crawling with that ratio would impress me.

Um, what? I can go like 30 in that gear, it's getting started that would take some grunting.

I was riding 48x15 for a while, and it killed my knees and made skidding a pain. You're not going to impress anyone with that crazy ratio, go with something more reasonable (16 or 17).

It's a result of mistaken order. I already exchanged for an 18t, which makes more sense.

Yo, I'm converting my track into a single speed, so I can skitch more.

49/16 with a freewheel and dual brakes. I think I'm going to be so into it.

I've been riding fixed for WAY too long, I need a break before I damage my knees anymore.

39/16, what do guys think about it?

39/16, what do guys think about it?
spin, spin, spin, spin, spin, spin, spin, spin, spin, spin, spin, spin, spin, spin...

EDIT: Actually, thats a little unfair. I would consider it too small for road, about right for easy offroad stuff. Unless you can spin your legs like an F1 engine, you'll probably top out somewhere around 18mph.

89/10?

I think i'll move to San Fransico.

39/16, what do guys think about it?
Depends - what cadence are you comfortable with? At 66 gear inches, if you routinely spin at 110rpm, that gets you to a 21.5mph top end. Much lower rpm, and you're getting pretty limited on speed. But you don't want to gain potential top end speed at the expense of your knees.

Never rode a road bike or anything bigger than a 20 bmx bike so i not really familiar with cadence, im just starting out and i am not really concerned with speed

Thats fine if your normal cruising speed is 32mph and your sprint speed is typically 48mph.

Al