The__Reaper

Hey guys; easy question.

Was running a 48/18 but with my setup it was out of line with the chain, switched it to a 44/18 setup for now. I'm kind of stuck with a 44 for the chain to line up with my wheel gear due to how the fixed gear sits on the wheel.

My question is; what should I run in the rear for more top end? I was pretty comfortable bombing hills with a 48/18 but id like something with more skid patches. What rear gear should I do to effectively have a 48/18 but with more skid surface? I'm not afraid to go a little higher i do have pretty strong legs!

Rolla

48 X 18 = 70 gear inches and 3 skid patch positions

A 44 X 17 = 68 gear inches and 17 skid patch positions.
A 44 X 16 = 72 gear inches and 4 skid patch positions
A 44 X15 = 77 gear inches and 15 skid patch positions.

I don't understand what the tooth count has to do with chainline.

caloso

Maybe it has to do with mounting the chainring on the outside of the crank spider in order to clear the chainstay?

Rolla

Probably so. I was confused by "due to how the fixed gear sits on the hub."

The__Reaper

This. The gear has to sit in the inside of the spider to keep the chain parallel.

The__Reaper

so running a lower sized ratio in the wheel side increases the gear inches. Thus making it harder on hills and easier on flats?

Also I'm currently running 44/18 which is 9 it seems. Would more skid patches make it easier to skid?

ofajen

If you can get a 41 or 43 chainring (both of which are prime numbers) the number of skid patches will equal the number of teeth on the rear cog. 43/16 would be very similar to 48/18.

Otto

Rolla

Yes. A smaller cog and/or a bigger chainring makes the gear inches greater, and thus harder to pedal.

There's no relationship between number of skid patch points and the ease of skidding. More skid points just means your tire will last longer (theoretically), since you're not always skidding on the same three or four places.

If you can run a 17T cog, you'll have 17 patches no matter what chainring you use (except for a 51). 19T = 19 patches. Take a look at this calculator and these tips.

Bat56

Not really. I'd say it makes it "harder" all the time. But since most hills have two sides, an uphill and a downhill, it's a bit tricky to say that anything makes "hills" harder or easier. Arguably, small enough inches would make going down steep hills very difficult!

As for flats, sort of the same thing. I think by "easier" you might mean easier to go fast. And if you have difficulty spinning your feet in circles really fast, then more inches will make flats "easier" to go faster. But all of that is relative to speed and power; gear ratios can't defeat laws of physics.

BikeEthics

Currently, I ride 48/18, and I like that ratio. But I do like to change the ratio once in a while.

nrosvall

I do long distance riding and randonneuring on a fixed gear bicycle. I use 46x19 at the moment.

BikeEthics

How do you like that ratio for long rides?

kingston 

https://www.bikecalc.com/gear_inches

70" is a good place to start. You can move up or down from there depending on your preference. More inches is harder to pedal/you go farther with each pedal revolution. I rode a hilly 1,200k last year with a guy who was running 85" (48x15), which is the tallest fixed gear I've ever seen someone run on a brevet. I normally run right around 70", a little lower early in the season, a little higher when I'm in better shape.

nrosvall

I do like it actually. Of course it limits how fast you can pedal downhills. For me it's on the sweet spot really. Good cadence when speed is 25 km/h - 30km/h. For long distances easy gearing saves legs too.