Singlespeed & Fixed Gear - Crank Size and ratio

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View Full Version : Crank Size and ratio


ironpuppy13
01-08-10, 11:50 PM
I'm really just starting to get into the biking game (at least the personal customization part) and i was wondering what some popular gear teeth ratios are. Your input is much appreciated


spcialzdspksman
01-09-10, 12:04 AM
46:16 is pretty much the mid-point ratio for fixed-gear riding on the road.
So get a higher gear if you ride in a hilly area, and lower if in a flatter area.
But don't take my word for it, head over to your LBS and try out some gear ratios first, and find out which you prefer. I suggest getting one that's slightly uncomfortable, since your body needs to adjust to fixed anyway, and you can actually train and improve because of it.

zeBRAHz
01-09-10, 12:13 AM
i ****ing hate these threads so much. ride what's good for you, it's that simple.


BoozyMcliverRot
01-09-10, 12:16 AM
46:16 is pretty much the mid-point ratio for fixed-gear riding on the road.
So get a higher gear if you ride in a hilly area, and lower if in a flatter area.
But don't take my word for it, head over to your LBS and try out some gear ratios first, and find out which you prefer. I suggest getting one that's slightly uncomfortable, since your body needs to adjust to fixed anyway, and you can actually train and improve because of it.


This is what you need to do.


QFT

bigvegan
01-09-10, 04:09 AM
This is what you need to do.

+1.

46:16 is good, it's what I've got on my bike, If you have a 48 tooth chainring, a 17 tooth cog will give you about the same results (75.6 vs. 74.2 gear inches). Basically, you want a ratio just slightly under 3:1 from your cog to your lockring (although if you're a detail person, you can calculate the gear inches - http://software.bareknucklebrigade.com/rabbit.applet.html)

If you want to do skids or go up hills more easily, a bigger cog / smaller chainring will be better, if you want to go faster on the downhills and flats and don't care about starting from stoplights or riding up hills being more difficult, a smaller cog / larger chainring will be better, but a 46:16 / 48:17 is a good combo to start with.

bbattle
01-09-10, 07:33 AM
Do you have a bike already? What size chainring do you have? Cogs are cheaper and easier to swap out and it's nice to have different sizes laying around in case conditions change. 48-18, 46-17, 46-16, 42-15 will give you gear inches in the mid-70's; a good place to be. If you've got mostly flat terrain, you might go to a higher ratio, 48-16 for example. Or if you've got a lot of hills and/or commute with a lot of stuff, go to 48-19.

Sheldon Brown has some useful info. on this subject and a gear calculator. www.sheldonbrown.com/gears Simply input your wheel and tire sizes, select gear inches from the pulldown menu, and input your chainring and cog sizes. You'll notice as you play with the calculator that a one tooth change on a cog gives a much bigger change to the gear inches than a one or two tooth change to a chainring.

Everybody rides a different ratio, don't feel that there's a "best" or "coolest" ratio. Although the ratio I use, 42-15, is pretty damn cool. ;) Almost as cool as the ratio on my other fixie, 48-17. Now that is one bad-ass ratio.

Ken Cox
01-09-10, 04:47 PM
Go here:

http://software.bareknucklebrigade.com/rabbit.applet.html

Take a few minutes to study this applet and play with it.

Most factory bikes come with a chain ring and cog ratio that provides about 78 gear inches.

For long commutes, I ride at 82 gear inches but find this too high, for me, when mixing with traffic.

The best all around ratio for casual riders seems around 72 gear inches, a little lower than most riders who start out on factory bikes think they like.

Those "in the know" generally describe 63 gear inches as the "do everything" street and mountain bike ratio, but this low of a gearing requires a VERY good spin, beyond the capabilities of many casual riders.

I presently ride at 61 gear inches and plan to move up to 65 gear inches in the near future.

Changing a tooth on a cog will result in a 3 to 5 gear inch change; whereas, changing a tooth on a chain ring will usually result in a one gear inch change; but play with the Rabbit applet and discover for yourself.

nashcommguy
01-09-10, 11:21 PM
46:16 is pretty much the mid-point ratio for fixed-gear riding on the road.
So get a higher gear if you ride in a hilly area, and lower if in a flatter area.
But don't take my word for it, head over to your LBS and try out some gear ratios first, and find out which you prefer. I suggest getting one that's slightly uncomfortable, since your body needs to adjust to fixed anyway, and you can actually train and improve because of it.

+3 This is the gearing I've got. Should've started w/48:15 as I outgrew 46:16 in a couple of weeks. Like the poster said, try different combos and find what works best for you in your particular terrain and traffic conditions.


i ****ing hate these threads so much. ride what's good for you, it's that simple.

It appears your reading comprehension skills are sorely in need of an upgrade. The poster quoted above said the same thing as you. With grace, skill and correct punctuation, too.

ironpuppy13
01-10-10, 02:34 PM
It appears your reading comprehension skills are sorely in need of an upgrade. The poster quoted above said the same thing as you. With grace, skill and correct punctuation, too.

lol

and thank you to everyone whos posted so far, you've all (except for zeBRAHz) been very helpful.