FarHorizon

I'm setting up a single-speed for relatively flat terrain. Assume some pannier loading when commuting.

How many gear inches should I be shooting for to avoid having to "stomp" up hills?

With an inexpensive rear cog, I can achieve anywhere from about 60 to 75 gear inches without having to change the chainring. I don't want to spin the pedals too fast or have too much tension on the pedals. So what's a good "compromise" gear-inch target?

Thanks - FH

well biked 

Most of the guys I know who ride their fixed gear bikes on regular road rides, with everything from long flat sections, to rolling hills, to mile-long 8-12% grades, will typically run around 72 gear inches. These guys are strong riders, and none of them particularly like the long climbs with a gear that high. But to reasonably be able to do road rides with others on geared road bikes, they need that many gear inches to be able to keep up on the flat sections. Often, too, the biggest challenge is long descents, where at 30+ mph they spin like madmen (not an issue of course if you're running a freewheeling singlespeed)

I have a singlespeed CX bike I do some commuting on, lightly loaded with a backpack, but with some climbing along the route, and I run about 50 gear inches, which is slightly more than the average singlespeed mountain bike, and quite a bit lower than the typical 'cross singlespeed. 15 mph on flat terrain requires some fairly serious spinning with that gear. But on that bike, for that purpose, I don't mind at all. Do keep in mind, even with a gear that low, it's still quite a bit higher than almost anyone would do any significant, extended climbing with on a geared bike.

Singlespeeds are fun, and they can make you stronger. But you will ride completely differently than you do on a geared bike. If you ride over varied terrain, you will quickly realize that you just have to make it work, your gear is either too high or too low to be ideal, and that's just the way it is. And that's part of the fun of singlespeeding. It can be a love/hate situation, for sure.

fietsbob

how about 61" ?

track riders have a Bag of cogs and chainrings and choose Ad Hoc. according to the track ..

I use a 3 speed 43.5, 58 , and 77 inch gears . (flat is not without wind to cope with as H-Tailwind L-Headwind, And 2nd for JRA on calm days .

You getting a Bigger frame Yet? one pictured before looked too small .. too much post and steerer height extension needed, to my eye.

a 3 speed has a 'range' between highest and lowest , a 1 speed has just a choice . no range just a Ratio. 1

FBinNY 

Somewhere between 65 and 80 is about right depending on how you ride. I rode a fixed gear with a 75" gear ratio for decades. It was high enough that I could keep up with timed lights in NYC, or descend a long grade without going crazy, and low enough that I could climb almost anything including some steep walls, and accelerate quickly when necessary.

You might buy 2 adjacent sized sprockets and so be ready to make an adjustment if your first guess is off.

BTW- do not buy a sprocket that divides evenly in to your chainring, ie. 48/16. Combinations like this mean that the wheel will turn an exact number of turns with each crank revolution, ie 3x, and the tire will always be in the same place during the power stroke, or when you skip stop. You'll end up with tires that wear much quicker in one or two places about 180° apart.

FarHorizon

Hi @fietsbob -

I'm thinking that 61 to 63 is just about right, based on some junkers I rode today for comparison purposes. Thanks for the suggestion.

No, I haven't changed bikes yet, and I'm getting frustrated. I've tried a set-back seat post, two or three different saddles, different handlebar heights, and different stem lengths. Nothing yet has made this bike even remotely comfortable. I may go looking for some alternatives. By nature, I'm attracted to coaster brake or internal-geared-hub bikes. They aren't the lightest or the most versatile, but for my needs, they probably suffice. The problem, of course, is that relatively few are made, anymore. One can buy flip-flop-hub "urban" bikes for peanuts, but they don't seem to be made for riders of substance, and they feel flimsy. New bikes with internally geared hubs cost a king's ransom, and often come with relatively narrow tires that are manifestly unsuitable for the "roads" I ride. MTBs come with durable tires, but I've yet to find one that I considered "comfortable to ride."

The "pros" may laugh at me, but for four mile stretches (with a brief walkabout between), I find that my humble Electra Townie 1-speed coaster-brake is a fine exercise bike for any distance up to almost 30 miles. That leads me to wonder if I shouldn't look at the Electra Loft & Ticino models with internally geared hubs... The Electras are NOT cheap for what you get, but until I find something more comfortable...

FarHorizon

Thanks, @FBinNY - I never thought of that! I'll make sure to implement your suggestion.

AnkleWork

Do single speeds "skip stop"?

DiabloScott

Skid patch calculator. BTW, any time you take the wheel out for a flat you'd probably be rotating the tire to a new spot relative to the crank skid position - so even if you have a 1-skid patch gear combo you can easily accommodate it.


OP talked about "tension in the pedals" and "spinning too fast" - I think he means FG when he says SS

Oh and BTW - 70" is perfect for my flat commute.

FarHorizon

The bike came with a 44/16 setup giving a 75.2 gear-inch gain. I found it too high for my taste (too hard to pedal). I then put on a 20t rear cog for a 60.1 gear-inch gain, and now it's too low (too easy to pedal). I'm thinking of changing to maybe a 18t cog for a 66.8 gear-inch compromise. About right?

FBinNY 

I never know when people saying single speed are talking fixed or freewheel, so I treat them equally. If the bike has a freewheel, then that will introduce randomness and there's no worries about "Indexed" tire wear.

noglider 

66.8" sounds great to me. Only you can say for sure.

FarHorizon

Thanks - My bike IS a freewheel (not a fixed gear) so no worries then about tire wear. FH

Reynolds 

42/16 or 42/17 is what I'd use.

noglider 

Those are 71" and 67", respectively, for whatever it's worth.

ThermionicScott 

Mid-60s is what I like for freewheeling single-speeds.

kingston 

I got at fixed-gear in October and after trying a bunch of gearing options in the I have settled in on 46/18 (69"). 45/18 (68") is just a little too low for going downhill and 44/17 (70") is just a little too high on the flat in a headwind. If I were riding with a freewheel and carrying panniers I would be comfortable going a little lower like a 44/18 (66"). For reference, I normally average 16-18 mph for 20-30 miles over relatively flat terrain.

noglider 

A one-inch difference on either end is a deal breaker for you? You must be kidding.

Reynolds 

Thanks Tom, looks like many of us prefer that gearing.

JohnDThompson 

Use a cog or chainring with a prime number tooth count and you'll always have the maximum possible number of "skid patches." Makes me wonder why 47T chainrings aren't more common...

kingston 

I guess that didn't come across right. I was just trying to explain how I arrived at my current gearing. I tried every combination of 44-45-46/17-18 and liked 46/18 the best. Maybe that makes more sense.

FBinNY 

A prime number rear sprocket won't help, it's the chainring that counts. Examples of prime number rear sprocket combinations that won't help are 13/52, or 17/51.

A prime number chainring makes you bullet proof, which is why I went with a 47t 45 year ago. However, the ring doesn't have to be prime, just so the Front/rear division goes to a few decimal places., ie. 48/17 or 49/16, or 50t with 15, 16 or 17t.

ThermionicScott 

I think "relatively prime" is the term for what we're after -- one or both of the two might not be a prime number, but if they don't have a common factor besides 1, then you get the full number of potential skid patches. For example, my fixed-gear uses a 45/16 ratio in the spring/summer/fall and neither sprocket has a prime number of teeth, but I still get 16 skid patches. (Not much use for me since I almost never skid, though. )

Beneficial Ear

Definitely stay under 70", when loaded up touring it takes alot of motivation to get a gear even this big spinning if you run into big wind or a steeper grade. I'd err on the low side, lugging a big gear is hell if the conditions make it tough and the motivation to push on isn't there. 65" is probably right, this leaves 20mph in reach but allows to really drag it slow up the hills/into the wind if that time comes.

noglider 

Nope, I don't believe that. I believe one test went better than the others, but not because of your ratio. They are too close to be discernibly different. Other factors must have been at play.

JohnDThompson 

Yes, but a prime number tooth count on the chainring means you can use any cog size you like and always have the maximum number of possible skid patches.