Another fixie question - what ratios?

Bullet1

So - just about to place the order - as standard the bike comes with a 44-16 setup.

Although the bike also has brakes this set up leaves 4 skid patches - is this too few and will it lead to lead to excessive tyre wear?

Secondly at my preferred cadence of 100rpm gives a speed of 21.5mph when my typical average speed for my journey into work is 18mph over an hour which give a cadence of 85rpm.

Will I find I'm 'mashing' more? Any thoughts? Is it worth changing to a 44-18 to be more in line with my averages?

Found the below link really useful in working thing out
http://www.surplace.fr/ffgc/

marcusjb

Don't overly worry about skid patches - unless you are skidding a lot or run without a rear brake.

44x16 is 72 inches and 44x18 is 64 inches - neither of which are too extreme in either direction. If you are new to fixed, then a little higher is probably better than a little lower - easier to leg brake and won't scare the life out of you on the descents. Start with the higher one and get used to fixed and then drop down as you get better at spinning.

Almost everyone I know on fixed will run somewhere between 65 and 70 inches on typical terrain (and 90% of them will be around 67 inches - the perfect gear for most as it'll get you up most hills, down them reasonably well and decent on the flat for cruising).

If your hub is double sided, then something like a 67 and 76 inch setup has you covered for most things. That said, I can rarely be arsed to flip onto 76 - never in that much of a hurry.

As I said, almost everyone I know will be between 65 and 70 inches typically - but it is something you need to work out. I have friends who do big distances and very hilly events on very tall gears of 85 inches plus.

dyrlac

I've been running 42 x 16 fixed (70.9 inches on 32mm tyres). 70ish inches is fine for my one hill route (max 10% but very short ramp), although I admit I'd like a slightly taller gear for the descents and maybe a bit of top end speed. As Marcus suggests, limiting factor for me seems to be spinning. If your preferred cadence is 100, you will have no trouble with shorter gearing. It's us mashers who need to heave on the way up to avoid killing ourselves on the way down.

iPete

This winter I've gone 44x16 (72 GI) and think its really good having come down a few inches.

Frustrating with a massive tailwind but can smash it home into a storm.

I'm riding this 20 miles each way on flat terrain and can get it around Richmond Park no problem. I'd recommend it as a good starting point. I've never had a rear brake but have also never done any skidzzzz

Take the bike as standard, you may need a few FG/SS tools to switch the gearing but it's easy and won't take long. As long as you keep it close, you can change the cog without needing a new chain.

telesv650

I'd not worry about the skid patches. Like ipete I've never skidded despite riding with only a front brake. Also your knees will not like regular pedal braking....

If you've never ridden a fix before you'll find you can pull surprisingly high gear no trouble, so I'd start at standard and work down if needed. I ride an old steel bike with panniers and find that as high as 48/18 is comfortable, however I tend to ride at lower cadences so lumping along at 70-80rpm suits me. It also depends on terrain as a big hills may determine the maximum gearing possible.

Bullet1

Thanks for the above - what / how are inches worked out?

JackPozzi

I tend to refer to this, doesn't tally with what people have mentioned on the thread but as long as you're comparing like with like it shouldn't be a problem...

http://www.velodromeshop.net/gearchart3.jpg

JayKosta

Bullet1 wrote:

Thanks for the above - what / how are inches worked out?

---

(chain ring / sprocket) X 27 = Gear inch
where 27 inches is approximately the diameter of the rear wheel.
GI is a concept of the distance traveled in inches from 1 pedal revolution (without bothering with that pesky pi business).

The concept comes from the old 'high wheel' bikes of the late 1800's where 1 pedal revolution gave 1 wheel rotation.

Jay Kosta
Endwell NY USA

iPete

Bullet1 wrote:

Thanks for the above - what / how are inches worked out?

I use http://www.bikecalc.com/ as it does things like cadence at speed and you can do lots of options at once.