Chain ring

Hey, I have been giving my old lotus conversion a makeover as it'll be a while before I get hold of another Bareknuckle. I have managed to respray all the old components apart from the chain ring. So I need a new one. But my lack of technical knowledge accompanied by the acronym BCD is worrying me. The bottom bracket I am using is the same as when the bike was originally a road bike (double chain-ring) will this affect my choices?

Bolt Circle Diameter.

This is the diameter of a circle drawn that passes through all five chainring bolts and it is absolutely vital that these are the same on both your cranks and chainring. What cranks are you using?

Ask yourself, what would Sheldon do?

turpe Bolt Circle Diameter.

This is the diameter of a circle drawn that passes through all five chainring bolts and it is absolutely vital that these are the same on both your cranks and chainring. What cranks are you using?

I think they are Sugino 75's.

Sugino 75s have a bcd of 144, but RDs (like the messenger cranksets and so on) are 130bcd. Be very sure, as the holes won't line up and you quite simply wont be able to screw the incorrect bcd chainring on at all.

Also, bear in mind that the chainring's dish (if any) may affect your chainline. I found this out to my cost today, as the new Specialities TA chainring I treated myself to was dished differently to the Sugino Messenger it replaced. Consequently, my bike is now having a new bottom bracket fitted to sort that little issue out - and, as I'm an awkward sod and ride a French track bike, I had to pony up the cash for a Phil Wood BB, as it's the only compatible bottom bracket that's readily available here in SF. Luckily enough, I had a sent of French threaded Phil cups floating about that I bought with the frame.

$120 waves bye bye...

Another factor to take into consideration is that, if you're putting Sugino 75s onto a JIS taper bottom bracket, the tapers won't match (75s are ISO taper) and that will cause you even more problems.

What's the BB - any ideas?

Ah, the joys of bicycle maintenance!

You'll want a 144 BCD chainring then. (Am i right?)

If it's the crank spider that had 2 chainrings on it, then i doubt it'll be a 75. I thought being track specific they'd only accommodate one chainring. But i've been wrong in the past! (Quite a lot actually)

Thanks for the advice. I am going to my LBS and see if they sort me out rather than wasting money on the wrong parts (which is envitable!)

On the subject of chainrings; does anyone have/know where to get 3/32 151mm BCD chainrings?

ebay.

campyoldy.com

Yeah Yeah, I've tried both Campoldy and Ebay (loads of people have 1/8 rings, SJS) but I need 3/32

So...Does anyone have a Black 130BCD chain ring they want to give/sell?

Vinz So...Does anyone have a Black 130BCD chain ring they want to give/sell?
Sugino make a couple (the basic Messenger, and also another less burly looking one). There's also a company called Rocket Rings that make chainrings with multiple drilling, allowing them to fit several different BCDs, including 130.

Also, check road, as opposed to track, chainrings, as the 'middle' ring on a triple crankset is quite often 130BCD - and the tooth count is normally not too far off the mid-40s, which is perfect for a fixed-gear drivetrain.

adoubletap Ask yourself, what would Sheldon do?

Decompose.

BringMeMyFix [quote]adoubletap Ask yourself, what would Sheldon do?

Decompose.[/quote]

brutal!

asm You'll want a 144 BCD chainring then. (Am i right?)

If it's the crank spider that had 2 chainrings on it, then i doubt it'll be a 75. I thought being track specific they'd only accommodate one chainring. But i've been wrong in the past! (Quite a lot actually)

Don't know if they have a 144 BCD but Sugino definitely do the 75 as a double crank as well, I bought one accidentally a while back.

Here is some info on 151 bcd rings - - -

1. Campagnolo, Sugino, and Shimano (Dura Ace) all offered 151 bcd rings at one point, in the late 60's. You can often find slightly used Sugino and Shimano rings on ebay for very low prices, some are in 1/8th and some are 3/32nd. NOS rings of this type are normally $100+, which leads us to a 2nd, cheaper alternative ....

2. There are at least 4 custom chainring makers in the world and they can make you a ring. This includes the mythical 43T 151 bcd ring that nobody ever sold as a brand-new item. The three sources for custom-made rings are :

a. Japan. CT Custom Chainring, but they may be closed by now.

http://velo-orange.blogspot.com/2007/02/ct-custom-chainring-shop-closing.html

b. U.K. Highpath Engineering.

http://www.highpath.net/

c. Australia. Probably the lowest-cost option. Cycle Underground.

http://cycleunderground.com.au/chainringdesigns.htm

d. USA. There is an individual that makes steel, titanium, and aluminum rings. I'm getting sick of googling and you'll have to look it up yourself. They serve the BMX or mountain-bike market. I never saw them advertise 151 bcd, but if they are making custom titanium rings, retooling for 151 bcd would probably not be difficult, and a titanium ring would last forever ...

Last year there was a 43t chainring in 151mm bolt circle diameter on Ebay, brand was Zeus and it was from the era when they used an outer ring with the tiny 50.4mm bcd circle like TA Cyclotourist and Stronglight 49, then the inner chainring was bolted to the big ring on a 151mm circle using standard Campy-style chainring bolts/nuts....but instead of a spider arm between the rings there was a tubular spacer around the chainring nut, like you'd see on TA and Stronglight and also many cheap old road double cranks where the big ring was also the spider....this allowed the smaller 43t size since the spacer could be quite thin, similar to 41t rings in 144bcd, and 38t rings in 130bcd....on all these you usually have to file/grind the spider tabs on a regular crank, to clear the chain (if the spider bolt-tabs are standard length, the chain will sit on them and be caused to skip since it's not fully down in the ring's tooth valleys)....some crankarms already have the ends of the spider bolt-tabs cut down, a few Shimano and Sugino and some others have been seen this way from the factory...but it's easy to do yourself, you simply file or grind the end of the tabs at an angle, just enough to barely clear the chain....you use the actual ring and chain to do it by trial and error, not difficult at home.