Convverting road bike

I run a 42/18 freewheel. Not found any hills I can't get up - might just be puffing a bit more. Steepest hill I regularly go up on my commute is about 1/2 mile long and probably about 4%.

My bike is a cyclocross style one, so has 32 or 35 mm tyres (can't read the thing on the side and not enough of a geek to measure them) on it that are a little knobbly. Got the bike as a winter commuter - figured the bigger and grippier tyres would help with bad conditions and bad road surfaces.

I use a 48/16. It's moderately hilly where I am and I find this a decent enough gear to push. Use the fixed for my commutes and a few shorter training rides. Great for cadence. Is better in the winter for control on wet and icy roads.

You will probably need a chain tensioner and when setting up, spacers for the correct chain line. You will notice the difference when you revert to a freewheel. I would also suggest either toe clips or spd's as you won't want your ankles to cop it if your feet slip off the pedals.

Ignore the naysayer at the first post. Expect to have fun and a great big grin on your face once you go fixed.

46/14 is very high, in fact that's the maximum gear limit for public training sessions at Manchester Velodrome and I've seen people race on less than that.

My SS road bike is 48/17, for fixed you'd probably want to go one gear lower to make it easier to use the gear as a brake (unless you're planning on having two brakes?)

I'm on 42/16 for what its worth, but it's a totally individial choice and also depends on your local terain.

For what it's worth, my tuppen'orth - it depends on how you'd like to ride it, your fitness and the terrain you'll be riding. You may well end up experimenting with a few different ratios or changing over time - I have. 46/16 is a good for me (after dropping down from 52/16 - can't believe I pushed that around for so long) but it's very personal really.

Couple of things to think about - you could break up an old cassette to give you free sprockets of different sizes to experiment with, but SS or track-specific sprockets and chainring are definitely worth the money - much less likely to jump and slam your knee into the stem/top tube. Also make sure you get the chain line and tension right. Half links or a half link chain help the tension issue, but a chain tensioner will very likely be necessary if you don't have horizontal dropouts. If you're getting a new chain you may as well go 1/8" - stronger than 3/32".

Enjoy - I'm actually singlespeed rather than fixed but different strokes for different folks and all that...

I recently did just this, went with 48/18 which is good until I get to a hill of more than 8% or so.... some pretty pictures here

http://jasontimothyjones.files.wordpress.com/2013/11/img_1061.jpg?w=762

http://jasontimothyjones.wordpress.com/tigger-bike-project/

for the winter you want a gear that will keep you toasty warm and that means one that will get those legs spinning - i.e. something like a 65" (48/19) should do the trick and you'll still be able to get up pretty much any hill

I have a new Langster, which thanks to illness I have done precisely one mile on so I'm not commenting from a position of massive experience

Surely the ideal gear depends on the local terrain

- maybe ride around in one gear on your normal bike, see what works and try to replicate that by counting the cogs and working out the gear size.

There's gear inch calculators online that should indicate the suitable cog sizes.

54:12 be a hero...

Plus it will make you fill out those hideously skinny jeans fixie riders insist on wearing.

Why would anyone want to do this,the free wheel was one of the best advances in cycling .why make your bike only have one gear when you could have 10 or 11.unless you intend to use it on a track ?but even then you would be better with a track specific frame.#mad decision.