Road Cranks on Track Frames

[tedschwartz]

I have an old track frame that i want to put road cranks on (dura ace 7700 octalink) I was just wondering about bb width. I know that most track cranks use a 111mm width. Should i be trying to find a octalink bb in the 111mm size or the recommended width for the actual cranks?

[rustychisel]

probably difficult in theory but easy in practise.

What is your intended usage? As a single speed or fixed for road or track?

Obviously if that is the case you need the correct chainline, which means knowing what rear hub and the rear spacing OLN. Road cranks should usually go on a road BB otherwise you run the risk of the shoulder on the inside of the crank spider hitting the chainstay. That will kill a frame pretty fast, and should be measured, eyeballed, measured very carefully again. On one of my frames the clearance is 1~2mm and I don't wish to drind off the shoulders on a DA 7402 crank.


I've never had any issues using a road BB and rear hub spaced as appropriate (110mm, 120mm, 126mm) to give a perfect chainline whilst having the chainring on the outer position.

[Peter B]

When in doubt ask Sheldon (http://sheldonbrown.com/chainline.html).

[Gummee]

FWI can tell, D/A track BBs are 109.5 same as the road BBs.

Get some BMX/SS chainring bolts and grind the protrusions off the backside of the spider and you've got a track crankset!

M

[pitcrew]

109.5mm in the Octalink bb is what you want (if you go the Octalink road/track crank route).

[tedschwartz]

the intended usage is as a fixed gear/singlespeed. i guess i'll try the 109 length and if it isn't quite right ill troubleshoot. for aesthetics sake i do not want the chainring on the inside of the spider. i'm planning on using a 3/32 chain, chainrings and cog. anything else i should know that sheldon cant answer?

[19wisconsin64]

hi, i ride fixed gear bikes, and also ride road cranksets on geared bikes...but as a fixie. usually i ride vintage campy cranksets, but the following advice should help......

if you get a phil wood bottom bracket then the installer can set it up so that the chain line will be correct with your single chainring on the outside of the crankset. there is a small amount of adjustability with these bottom brackets.

otherwise, you may have to mount the single chainring on the inside for chain line purposes. you can make this look better by using track (shorter) chainring bolts, otherwise you will have to use spacers with regular width chainring bolts.

funny you should mention sheldon brown.....he was really big into french bikes and consulted me on how i should set up my motobecane as a fixie. he knew so much!! good luck!

[oldpotatoe]

I have an old track frame that i want to put road cranks on (dura ace 7700 octalink) I was just wondering about bb width. I know that most track cranks use a 111mm width. Should i be trying to find a octalink bb in the 111mm size or the recommended width for the actual cranks?

Match the BB to the crank, not the frame. 7700 uses a 109.5, version 1, octalink. No such animal as a 111mm octalink.

[Gummee]

the intended usage is as a fixed gear/singlespeed. i guess i'll try the 109 length and if it isn't quite right ill troubleshoot. for aesthetics sake i do not want the chainring on the inside of the spider. i'm planning on using a 3/32 chain, chainrings and cog. anything else i should know that sheldon cant answer?
If you're riding with pants on, get a big chainring and grind the teeth off to make a matching 'chain/pants guard.'

S'what the PO of my Specialized cranks did. I've got 144mm BCD cranks so I can use pretty much any track chainring I wanna run. :thumb:

M

[11.4]

Actually, the neatest approach is to get a Sugino Messenger 144 BCD chainring, mount it on the inside position, put a cyclocross chainring guard (from www.cyclocrossworld.com) on the outside (which then allows you to use regular double chainring bolts) and mount with a 109.5 mm Octalink bottom bracket. You have plenty of choices in the latter, but my number one recommendation would be a BB-6500 Ultegra and my number two would be a BB-7710 Dura Ace track (which is the same except for steel cups and an NJS stamp).

With this setup you'll have a decent chainline (which is really your biggest problem with road cranks in a track setup) and can use a track chain so you have fewer worries about dropping a chain and have some good chainrings to go to. The cyclocross guards are nice and less than the cost of a chainring anyway, and God knows you don't want to have to do all that grinding.

[ultraman6970]

Pretty much you have to just put the crankset in there using the default BB axle.

Depending on the read hub u might or might not have chain line problems. If you are using something wide like a shimano or a campagnolo track hub probably you wont have a single problem.

If you are using a road threaded hub you can put the axle backwards and redish the wheel for example. But always you can put a BB spacer between the cog and the hub to correct for those 3 mm or more if the chain is off.

For the record that you are off 2 mm doesn't mean the chain will explode, just make the wheels turn and shake the bike, thats the classic way to check if you are going to have problems. People sometimes is too picky about chainlines but you always have a slack because the chains are flexible too.

Ok many are thinking in performance, to that my answer is... if you are not a world class track racer or road racer WHO CARES ABOUT the chainline too much!!! if the chain line is a tiny off, probably nobody will notice the difference in performance anyways, besides doubt the chain will come off or explode because it cross 1 or 2 mm.

Good luck in your project.