FINALLY got my first fixie rolling on two wheels! It's a discarded Fuji I received from a friend when he bought his carbon fibre creation. Rocking a 44X16 on 27X1 1/4 treads, ghetto-cut and flipped drop bars, ghetto cork tape job with getto black tape makin it look purdy. Did I mention the metallic blue rattlecan paintjob. Looks right nice with the gold rims.

I was going through my old BMX stuff and found 2 16t freewheels, and a bunch of front sprockets i could use. I was going to go with the 42t Biopace ring, but it was silver. Nah, thats just crazy talk!

biopace would make your chain tight then slack all the time ...

(PROGRAM)
G90G17G49G80G40S500
G92X0.0Y0.0Z2.
M22
N1T14M06
(MILL-375)
(PLANAR_PROFILE)
M01
G54
G0X-4.4789Y-.238
G43H14Z1.S3500M03
Z.5
Z.375
G1Z-.125F35.
X-4.4235Y.041
G2X-1.3343Y1.2597I1.9146J-.3287
X-1.3321Y1.2581I-.1138J-.1578
G3X.469Y.6723I1.7336J2.2686
G1X7.308Y.8293
G2X7.3081Y-.8293I.019J-.8293
G1X.4154Y-.6723
G3X-1.024Y-1.0238I-.0674J-2.8474
G1X-1.0461Y-1.0463

It would seem that way, but no...
It's a perfect (symmetrical) ellipse. Therefore the same number of teeth are always engaged w/ the chain.

So, you can make a Biopace fixie?
Anyone tried this?

Sheldon Brown has, and apparantly it works out a-ok. Claims slight change in chain tension but not enough to matter.

https://www.sheldonbrown.com/biopace.html

My buddy ran this for a while both as a SS and a fixie. No issues at all.

it would seem to me that running biopace wouldn't be a problem on rigs that have quite solid chainlines and for people who don't do a lot of hard backpedaling -- namely skidding or other harsh stuff. in general those things are safer when you can keep relatively consistent and solid tension. as such, i would be very hesitant to roll with biopace on any brakeless setup, but that's just me.

I would be hesitant to roll with any brakeless setup at all. Why would you purposely remove something that can cut your stopping distance in half?

the brakeless debate has and will continue to be had on these forums, but not in this thread. i simply intended to point out that, if one is already inclined to ride without brakes, it is probably advisable to avoid biopace.

It looks like the machine got all effed up and they decided to sell them anyway

You work with cncs iso?

yeah, i do. do you? i do some machining, but mostly just do all the cad/cam work. i had just posted a program before reading this ******** thread and thought i would also contribute equally useless information!

and about the biopace chainring on a fixie... my roommate did it once, just because. the chain tension didn't really change, but the chainline sort of moved up and down. he said it looked pretty weird, but worked. then a princess busted through the door on an angry unicorn and shot everyone in the face with a machine gun, then threw up her breakfast from earlier in the day. everyone swore it was scrambled eggs and oatmeal, but she insisted that it was lucky charms. but what do they know? they were all dead. the end.

Frankenstein doesn't scare me. Marsupials do though. Cause they are Fassssst.