bikenh

I've been seriously considering switching from geared to fixed gear riding. I've been riding a cassetted bike, single speed ever since last August. Hence why the cassette has around 11K miles on it and it's still in quite good shape...I hardly ever switch gears and stay on the cog until the chain and cog are junk then I change the chain and the cog and do the same thing all over again.

For the most part I've been riding either 52x17 or now 52x19. I think the 19 is mostly due to having time off the bike thanks to a broken ankle about three months ago.

I had been saying when I make the switch to single/fixed gear I would go to a 52x17. The problem was I saw online that once you lose the extra gear shifting devices off the bike you increase the efficiency by 10-15%. I also saw, thanks to riding one legged with the broken ankle on the open road that you also gain extra power in the pedal stroke when riding fixed gear. Boy, fixed gear one legged biking would have been so much simpler on the climbs. Having the spinning wheel helping to spin the pedals around makes for easier pedaling one legged...that's for sure. It seems like I had also seen somewhere that you normal gain something like 5% as a result of going from single speed to fixed.

That brings up my question. With the extra increase in efficiency doesn't that make gear selection to a bigger gear(gear inches) more sensible or not. I'm now thinking I would probably want something more like 52x16, if not 52x15.

Am I right or wrong in my understanding that by going to single speed/fixed gear I would want a bigger gear inch than what I'm currently riding all the time on a cassetted bike when riding in 'single speed mode'? How much bigger should I be looking at if I'm correct in my thoughts?

seau grateau

Nah, that's not really right at all. Choose the gear that you're comfortable pedaling.

Huffandstuff

52x16 would cause your knees to explode with daily use.

Ideally you want to run in the high 60s to low 70 gear inches.

GMJ

I say go for the biggest gear you can handle with elevation/stopping, as long as your knees are in good shape.

52x17 is a reasonable gear for a lot of people. Try it out and see where you need to go from there.

Jandro 

Where the **** are you getting all of these numbers? I'm not going to pick apart each one individually; suffice to say, they are all wrong.

52x17 = 80gi, a track warmup gear. Ok for FLAT riding, **** for climbing.
52x16 = 86gi, a track RACING gear.
52x15 = 91gi, a HIGH track RACING gear.

1 of the above is ok if you're in Florida.
2 of the above are only advisable on the track, 52x15 is about where upper cat track racers gear and I'm 99.9% sure that it's close to 15gi too big for you.

Are you going to be running a brake on this? What are your typical distances and elevation gains on a ride? Without this info, we can't even begin to help you choose something. Shoot for 70-75gi to start off with. I race track and road and I wouldn't put over 75gi on my track bike for city riding. Currently I'm running 49x18 (71.5gi) and it's prefect for just about everything except hauling ass on flat ground at 24+mph (115rpm).

Handy gear inch calculator.

Jaytron

This thread made my head hurt.

GENESTARWIND

52x19 is what i run and I'm pretty happy with it.

Philasteve

Damn, these numbers make me feel like a weakling. I would never run a huge gear like that without a front brake, even still I don't ever run more than 75 gi with a brake. On my fgfs bike I run 36 14 and it's brakeless but I have never had a problem or close calls commuting on it.

Jaytron

I run 49x18 on the road FWIW. Sometimes I want to spin more though.

GENESTARWIND

i used to run 49x17 and am so glad for the change. yeah i could mash some speed but climbing is so much easier now! and i can still hit speeds if i spin.

rex615

I run 52x20 which is about 70 gear inches. Any more and I can't climb the hills around here, any less and I can't go down them.

It is about perfect for the flats, but then I am not that fast.

bikenh

Right now I'm riding a 52x19 all the time, I'm in recovery mode from the broken ankle three months ago. Last summer I was riding 52x17 pretty much from mid-August until late October when the gear/chain junked out on me and I dropped down to the 52x19 to repeat the process. Mid-August through mid-September I was on a bike trip from New Hampshire to St. Louis and rode pretty much the entire roundtrip ride single speed in a 52x17. I started riding single speed with the start of the trip...why spend the money replacing chains and cassettes when you can ride it single speed and only waste a gear at a time instead of wasting all of them at once. I started riding single speed back then and other than riding one legged thanks to the broken ankle I've been doing it since last August. Over the winter I was typically riding the 36x13 or 36x12. Yeah, I got 11,000 miles on the cassette on my bike right now and have only used four chains and most of the gears are still usable. I thought I had junked out the 52x19 but turns out the bent derailleur hanger was making me think it was time to replace the chain and to change the gear I was riding in. I've ridden over 800 miles on the 52x19 since replacing the derailleur hanger.

I ride big gears all the time. Typically, until this past weekend I haven't been much of a spinner. I always stand to climb hills and ride big gears. Like I said right now a 52x19 has been the norm for the past several weeks since I came back to two legged biking.

October 2011 I climbed one of the steeper climbs around here in a 53x15 seated the whole way up it. In fact the tail end of that 120+ mile ride I rode seated in a 53x15 to see if I could do it or not and to make myself pedal slowly. No I don't spin my way up a hill, I power my way up a hill.

Around here typically you find 50-60 feet per mile on average for climb rates. Mostly it's rural riding with some small city riding on occasion depending on where I'm going.

Doing the looking, since I plan to convert my road bike over to a fixed gear bike, it looks like I'm in the right ballpark anyways. a 52x16 should work with the vertical dropouts on my bike. The next lower gear that should work would be a 54x18. Something tells me I want the bigger gear for the descents around here so I don't have to brake on the descents. Right now I can ride and still be applying pressure to the pedals up to around 145-150 rpm. After that I lose pressure. Since this past weekend I've been intentionally riding pedal pressure all the time and riding 30.5 mph going down one of the hills I see each day/several times a day and riding it in a 52x19, hence roughly 140 rpm. I have hit around 31 going down it but I know one of the other hills where I see 35-38 mph regularly I lose pedal pressure as I hit top speed. I'm guessing my max rpm right now is 145-150. Doing the math I see 150 rpm in the 52x16 gives me 37.85 mph. The 48.5 mph I hit on the fastest drop around here I was fully tucked going down the drop versus staying upright to grab more wind to help me stay slower and help to keep me from having to brake as much. I know I can still get up it in the 52x16 as well.

Yes, I plan to have both front and rear brakes on the bike. Why wouldn't I? I'm not doing this for a track bike, I'm doing this for a road riding bike/touring bike.

Yes, last summer I almost managed to grab a solo sub 5 century, without aero bars, and with 4700 feet of climbing here in western NH. If it wouldn't have been for the darn stoplights I had through the center of the ride I would have grab a solo sub 5. I ended up with 5:11 on bike and 5:03 moving time. Yeah, a lot of wasted time at stoplights.

How much of a difference do you see between geared and fixed gear biking in terms of what you feel comfortable riding gear wise. I would think if the efficiency is that much better and the climbing is also made easier that it would make sense to ride a bigger gear while riding fixed as compared to riding freewheel with derailleurs.

David Broon 

You aren't istening. There is no magical efficiency boost. If anything, you probably loose some.

rex615

This.

The gain in efficiency in a fixed gear bike over a properly maintained (clean, lubed and adjusted) derailleur bike is very small. Certainly not enough to account for a gear increase requirement. You would need the same gear as you did before.

yummygooey

i feel bad for your knees

IthaDan 

Have we established he's turning a 700c rear wheel? Last time we got into this, the kid was on a mountain bike.

Muffin Man

It made my knees hurt.
I run 48x18 on the road, and I like it going uphill, but I hate descending.

solipsist716

Best troll evar.

OneGoodLeg

Right now, I'm running 44x14, which is about 83 inches. Bear in mind, part of my reason for riding is to rehab and stregnthen my surgically repaired leg. I've only had that gear setup for about a week. And, I've slowly increased my gear ratio over the last two years. Previously, I had been running 44x15 for about a month. Prior to that I rode 44x16 for about a year. While averaging about 800-1000 miles a month.

I actually find 44x14 easier for climbing hills. Based on my average mph over my commute, which is about 25-30 miles a day, I'm spinning 60-70 rpm at that gear ratio. That includes climibing some small hills.

This weekend I'm switching to 46x16, because the current 44t chainring is getting worn out and needs to be replaced and I want to spin more while increasing my commute mileage as the weather improves. I'm just psyched that my leg is back to where it can handle the higher spin rate, it's only been two years, it feels like a decade.

Based on bikecalc, 52x19 is only 72.5 in.

49x18 is 72
48x18 is 68.8

Not huge differences if the chart below is accurate.

hank0604

Another thing to consider is that you are riding singlespeed right now, not fixed, and you really don't have an appreciation for how much you coast now.

When I decided I wanted to go fixed, I thought to myself "I hardly ever coast, so it won't be a noticeable difference to flip the hub." Wrong. It was a very noticeable difference. Anyone with a freewheel will coast little bits here and there A LOT, you just don't recognize that it's happening. Suddenly not being able to coast those little bits will add up. Over the course of a 35-40 mile ride, you'll certainly notice the difference.

Don't be a hero and don't measure your manhood by your gear ratio.

Jandro 

Gotta be this.

bikenh - do whatever you want since you aren't here for advice. Report back.

gregjones

I get to town and back a faster when I run a freewheel. It's the downhill coasting speed. I can't match it fixed.

Not being in any hurry, I prefer fixed. It just feels better overall.

bro

samesies

bikenh

I actually find bigger gears are easier for climbing as well. When I was riding one legged last month it was a pain to drop down to the small chainring. It didn't feel like I was putting any pressure on pedals thus it made the climbing awkward. I couldn't spin one legged much above 65 rpm so I spent most of the time riding a 52x22. I would be pedaling 25 rpm at 4 mph but it sure felt better than trying to keep pressure on the pedals in a 36x22 at the same speed. I rode 21,200 miles last year and have gotten myself in shape by simply riding the bigger gears and keeping the heart rate lower. Yeah, I can't accelerate like the pros and can't maintain high speeds like the pros, then again I'm not racing like the pros either. I ride for transportation and recreation not for racing. I had seen somewhere online that their was a difference between riding freewheel and fixed of around 10-15% more efficient simply because you don't have the extra drag created by the derailleurs, by the chain that isn't moving in a straight line and also because of having less weight on the bike because of the extra missing equipment. You also get the benefit of not being able to stop pedaling. That makes it easier to pedal as a result and not more difficult. I saw that with the broken ankle. The climbing would have been so much easier if I would have been riding fixed mid-March to mid-April instead of riding with a freewheel. I was pedaling the entire way around since I was only using one leg anyways by having the moving wheel helping to rotate the pedals around. It would have been a nice benefit to be fixed on the climbs. I can see when riding in cities that riding smaller gear ratios has its benefit because of the starting and stopping at stop signs/lights but when doing mostly open road riding where you are trying to keep a consistent speed I see using higher gear ratios to be more of a benefit to help you keep from spinning out so easily, especially in hilly territory where I live. Pretty much everyday I hit 38 mph on one downhill or another, whether I'm tucked or not. Having higher gear ratios makes it a heck of a lot easier on the knees when descending. My knees don't hurt at all when climbing. I could imagine what they would feel like/how hot my rims would get if I were using 70gi around here. Pure insanity.