arneyz

Hey all,

I'm converting an old Miyata Ninety ten speed to a fixie. I need to know what gear ratio would be a good one to start on. I read through that getting started thread but it was talking about measuring in inches and I don't really know what that means. Something about 65 to 70 inches? How does that translate to number of teeth on the chain wheel and the cog?

This will be a commuter in a place with some hills but mostly relatively flat terrane. I'm used to riding BMX dirt bikes from when i was younger but those have longer cranks than road bikes.

If I need to give you more information let me know.

Thanks,
Zach

hammerdown48/13

check out sheldon browns gear calculator... easy conversion online
https://sheldonbrown.com/gears/
my first was a 48/13.... which was burly... but it toughens up your legs quick.... and if you learn to skid on sumthin that high, runnin it lower is a breeze.... i now ride a 42/13 which converts to somethin around 82in... my suggestion is something around 42/16.
good luck

cblaster

The numbers on the top cells of the chart are the number of teeth on your chainring, and the numbers on the leftmost column of cells are the number of teeth on your cog. Where those two columns intersect will tell you how many gear inches you are running, or how many skid spots you have.

The more gear inches you are running, the harder it'll be to pedal. I'm running 70.5 gear inches and it's fine for the mostly flat city I ride in - I do find myself wishing I could go a bit faster though, I'll probably get a smaller cog when I get some extra cash.

arneyz

Alright well i rode my first fixie today. it had a 46t chain ring and a 18t cog. I liked the feel of it i think i might go with a 42t/16t ratio to give it a tad more resistance.

I have a second question now though. the guy at the shop informed me that I have 27 inch wheels in my bike and that the wheels i would get are 700s (mm I assume). He said they are compatible for the most part (the diameter difference is less than a centimeter) but i'm still a little wary of not using wheels of the size the frame was meant for. Are 27s still made or do i have to switch to 700s? If switching is legit, I assume I'll need to get new breaks which i was planning on anyway, just a front. Will there be any compatibility issues with those?

Thanks again for the help.

hammerdown48/13

i put 700's on an old frame designated for 27's and had no problems... you may be able to salvage your old front break with some simple adjustments depending on what you got... i had no problems... try it before investing loot into new ones. gratz on the new ride.

arneyz

I just measured the distance between the tire and the break mount and it's a little more than a centimeter, about 1.5 cm. Is that enough room. I guess there doesn't really need to be room for movement like a mountain bike. but i want to make sure.

hammerdown48/13

if it clears you are golden.... with the measurements youve given it sound like youll still have some clearance room... you may not be able to fit cyclocross tires or anything too burly, but you'll be all good with an average road tire. there isnt any give when you are bolted in... so dontcha worry about that. just make sure you clear your down tube.... and that you are comfortable with the foot play. sounds to me like you are ready for new wheels.

arneyz

Thanks!

This has been really helpful.

hammerdown48/13

go hit those roads!