garythenuke

I got a screaming deal on a stock 925. It is an older model (the black one), and I got the complete bike for $275. It rides awesomely. But the fixie ratio is 42/15 (42/16 in the ss mode). That gives me only five skid patches. I would like to find a 43 or 41 tooth chainring. Is there such a creature?

ZiP0082

Rocket makes one that fits 110 BCD and 130 BCD:
https://wheelandsprocket.com/itemdetails.cfm?id=7130

garythenuke

Thank you, Thank you, Thank you.

Another question... 3/32 is the most common size right? Is there an easy measurement or should it be pretty obvious as to which size I have? My hunch is that since this is a stock low end bike it will have the 3/32.

ZiP0082

Some track bikes and some BMX bikes ship with 1/8, but I'm willing to bet your bike is 3/32. Like you said, it is very standard. Even if you did have a 1/8 chain, you could still run it on a 3/32 chainring (but can't do it the other way around).

Also, you probably know this but BCD is the distance between two adjacent chainring holes. You'd want to make sure your current cranks have either 130mm or 110mm between each crank arm/hole before considering a rocket chainring.

garythenuke

Thanks again Zipoo. I just looked at my current chainring and it is labled 42T 110MM BCD. So it looks like I am okay with the chainrings you linked me to.

edit: I just placed my order for a 43T. WAHOOO!!

jonestr

Bolt Circle Diameter so the distance between adjacent holes is not the diameter as line does not pass through the center of the circle that has all of the bolt holes on its circumference. I think Sheldon has a conversion from measuring between adjacent holes and finding the BCD.

Rocket Rings should take both 110BCD and 130BCD

garythenuke

What are yall's opinions on chainring wear with odd numbered teeth versus even? It seems like increasing skid patch count is more valuable than worrying about tooth wear, but I'd be interested to hear what other's think.

I got this notion off of Sheldon's site. I had never considered it before.

tmh657

Hey nuke, FYI 1 tooth on your chain ring, from 42 to 43 is not going to do much of a diff in gear inches ya know. If all you care about is skid patches then cool, get the 43.

I have an '07 Redline 925 and it's great. I have the 42_15, I like to run 44_15 for a little taller gearing and went with 42_14 for just riding flats.

I got a Sugino messenger crank with 1/8" ring and went to 1/8" cog, a surly or dura ace. Got velocities, a fixed/ fixed rear and gatorskins, carbon fork, riser bar, sanded the 14 tmies it said Redline on the frame off and painted it. yada yada. It is super smooth. Way better than any conversion I have built, except for the Pinarello, yummm.

https://velospace.org/node/11735

garythenuke

Wow! That is a beautiful setup tmh.

I wasn't shooting for bigger meat in changing chaninrings. Actually I am pretty happy with the feel of my 42/16 ss side. I was going from 5 skid patches to 30 (ambidextrous). I'll keep the 42 for kicks. Maybe my son will want to use it someday. We bought him a redline monocog a few weeks ago. I am so darned proud... Only 13 and already choosing singles speeds.

ZiP0082

Ooh, thanks for that clarification in terms of measuring the BCD.

ben_liu

Here ya go:
https://www.hostelshoppe.com/tech_bol...e_diameter.php

tmh657

I think I'll get a recumbent fixie, and do some hostile shopping