rgoo92

im about 5'9 with a 54 road bike frame that im converting into fixed gear

shopping for new crankset right now and had a few questions

im lookin for 48t chainring
whats difference between 1/8 and 3/32 chain?

alot of them say like 130 BCD - wut is this?

and they also say like 160 or 165 mm too - what measurement is this for?

mtbikerinpa

1. Chain width of 1/8" or 3/32" pertains to the width that the teeth fit into. Narrower chains are used for shifting, fatter for single or fixed gear.

2. 130 BCD is 130 milimeter Bolt-Circle-Diameter. This is the measurement between bolts on the arm itself, measured in a few methods.

3. 160 or 165mm is the length from the crank bearing(bottom bracket) to pedal. This is a fitting measurement depending on your individual leg stroke.

rgoo92

how do you recomend i find these measurements?

LesterOfPuppets

FIRST, you need to find a crankset that matches your bottom bracket...

Then, you'd have to check the specs for the crankset you're looking at to find the BCD, then you can start hunting for chainrings.

If you're shopping for cranks from parts bins, bring a metric rule with you and a cheat sheet for the adjacent bolt hole center multipliers found here..

Ahh, I might as well paste it too, why not:

Take the adjacent bolthole (center to center) measurement and:

Multiplying this dimension by 1.701 will give you the actual BCD for a 5-bolt chainring.

Use 1.155 for 3-bolt chainrings, 1.414 for 4-bolt chainrings and 2.000 for 6-bolt chainrings.

Crankarm length is pretty easy to figure out, center-to-center pedal hole to spindle hole.

Squirrelli

https://cgi.ebay.com/48-TOOTH-TRACK-F...item518e932c50
Here's a ring that takes both 110/130 BCD.
Cogs usually come in 1/8" and you need a 1/8" chain, but you could use a 3/32" chain ring with a 1/8" chain.
Shorter crank length gives you slightly more room when you round a corner, fixed gear riders usually prefers 165mm or 170mm cranks.

LesterOfPuppets

Sometimes it's cheaper (or at least almost as cheap) and easier to buy BB, Crank and chainring all in one package. Depending on the roadbike's age, you'll frequently just need to determine the proper BB threading. Some newer bikes might get tricky and some really old bikes might get tricky.

rgoo92

uhg this is all so much more confusing than i thought. let me research more then get back to you guys

chainring
chain
crank
crank bearing
bottom bracket
sprocket
cog
crank arm

LesterOfPuppets

It might not be that tough. Do you know the Make/Model/Year of your frame? Or could you post some pics?

If you're looking to do it yourself, tools may be required as well.

Unless you REALLY love the frame and have a REALLY good reason for the conversion, you may be better off just buying an off-the-shelf fixed gear bike.

rgoo92

ill throw up measurements w/ pics tommorow !
ive gone too far to buy a new fixie. and this is all a learning project/experience

LesterOfPuppets

Gone too far? Ack! What did you do?

rgoo92

already have a frame , fixed and front wheel, pedals seat dropbars

LesterOfPuppets

Ahh, OK, totally bare frame then? If so, you'll need to determine bottom bracket threading.

rgoo92

yea my frmae is stripped
its a 1989 master centurion ironman or osmethign
ill get pics and all tommorow

how do i measure threading? bottom bracket is jsut that little hole right?

LesterOfPuppets

English thread bottom bracket, then

rgoo92

what? lol i odnt understand

Squirrelli

Oh you got the frame from LAriding?
Bottom bracket is the spindle with bearings, bottom bracket shell is that little hole on the frame where the assembly goes into.

rgoo92

yea we traded our frames he was very helpful and etc

is the bottom bracket part of the crankset? or do you buy it seperately

LesterOfPuppets

Well, say for instance you wanna buy a Centaur BB from PBK, go for the English one.

LesterOfPuppets

You can find complete BB/crank/chainring setups or you can buy them independently.

I'm more a road bike guy, tho, so perhaps a fixed wizard will chime in ...

rgoo92

mnaw this is fine im on a budget for now so ima check out those allinone setups haha

Squirrelli

LAring seems to be a pretty nice guy, I love his red Peugeot.
Bottom bracket and crankset are usually sold in set if they are higher end.
You could buy it separately though.
I'd recommend buying this crankset; however, you will need to buy separate bottom bracket.

rgoo92

yea hes real chill i saw his puegeot it was sick haha


uh im so confused. i thought chainring was part of the crank

vixtor, is that eighth-inch crankset better than https://cgi.ebay.com/TEC9-FIXED-GEAR-...item27b18b7703

this one fits both chains, also requires bottom bracket, and 130bm

Squirrelli

A crankset is consist of two thing mainly, a chainring and two cranks and bolts that hold the chainring on the one of the cranks.

That Tec9 looks really good just for a starter fixie, get it if you want to...barely 50 bucks + shipping, good deal 160mm is kind of short though, get the 165mm.

However, I'm not sure what bottom bracket length you'll need but a 103 bottom bracket would give you a straight chainline.

LesterOfPuppets

160 is way short for me. Have you taken note of what crank length you've ridden on before, rgoo?

rgoo92

no i am a complete noob =[
i currently have no crank so i need to get myself measured

vixtor is the 8th inch a better company? or is there something you like better about them? tjheyre the same price