Crankset.

Seaswimmer

Any suggestions for a 42T crankset for a fixed speed project. Can you buy one on its own. Most of the popular makes sell them in double sets 52/42 ect. Could you get a double and only use the inner ring??

flickerx

Seaswimmer wrote: »

Any suggestions for a 42T crankset for a fixed speed project. Can you buy one on its own. Most of the popular makes sell them in double sets 52/42 ect. Could you get a double and only use the inner ring??

Check out wheelandsprocket in the states. They have an eBay shop.
There's some other shop that do Sugino Messenger Cranks with a 42t chainring for cheap enough but I cant remember the name of it now... argh...

You could get a double and use the inner ring, but if the chainline doesnt run straight from the inner ring to the sprocket, then the chain would be knocking against the larger ring.

I've got an old hard fused double crank in my back garden if you want it on the cheap. It needs a bit of a clean and I havent taken off the pedals but I'll get them off, I always do It would fit onto a square tapered bottom bracket. Let me count up the teeth and get back to you again on it... I think the inner one might be 39 or 42.

thesunwashot

You could use a double but you may as well buy a track crank if that is what you actually want.

hubjub have some sweet ones if you have loads of cash:

Sugino: http://www.hubjub.co.uk/sugino/sugino.htm

or slightly less:

Stronglight: http://www.hubjub.co.uk/stronglight/stronglight.htm

www.sjscycles.co.uk have some seriously budget ones if you don't.

You can buy the crank and chainring as separate items. You just need to make sure they are the same BCD/PCD. The Stronglight mentioned above is 130mm BCD which is common for road bike chainrings so you'll have a huge choice. The Sugino is 144mm which is the track standard. There are various other sizes (BCD sizes) but you may struggle to get singlespeed chainrings for them.

Most makes of chainring come in a range of differing numbers of teeth so this shouldn't be a problem.

A chainring designed for singlespeed doesn't have the shaped teeth that aid gear changes and so in theory will not drop the chain as easily. I don't really know how much of a difference this makes in reality. Dropping the chain on a fixie isn't a great plan though.

The other thing to keep in mind is that you may need to change the bottom bracket to get a straight chainline depending on what BB you currently have and what the spec of the crank you buy is. This can wait until you see how your chainline turns out as BBs are pretty cheap.

hope that helps rather than confuses...

flickerx

flickerx wrote: »

I think the inner one might be 39 or 42.

Just counted it. Inner one is 42, outer 52.

I'll clean it up at the weekend and post some pics if you want. Let me know if you're interested. I should be around for part of next week.

Daveskig

there is some excellent advice above. i just want to add some more snippets.

if you have a double and want to ditch one ring, you may need to buy shorter chainring bolts.

also, not only do road chainrings have funny shape teeth, they are, often oval, which is a problem.

horizontal(ish) dropouts are necessary to get correct chain tension.

Seaswimmer

Thanks folks for the good advice. I will probably buy new from hubjob. One final question... Can a cup and cone bottom bracket be replaced by a cartridge type BB. I am using an old Raleigh 531 frame for this project and want to change BB as original one is 20+ years old..

stuf

There's a good thread on this here:

http://boards.ie/vbulletin/showthread.php?t=2055294511

I've also found a good package on ebay:

http://cgi.ebay.ie/TRUVATIV-42-SINGLE-SPEED-CHAINSET-CRANK-BOTTOM-BRACKET_W0QQitemZ110271278590QQihZ001QQcategoryZ109118QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

and if you go down that route then you know that the BB spindle is the correct size for your crankset

Thomas_S_Hunterson

Seaswimmer wrote: »

Thanks folks for the good advice. I will probably buy new from hubjob. One final question... Can a cup and cone bottom bracket be replaced by a cartridge type BB. I am using an old Raleigh 531 frame for this project and want to change BB as original one is 20+ years old..

I'm not 100% on this but it might be worth sticking with the cup and cone as it offers some adjustability with regard to chainline.

If it still runs smooth, there's no real need to change.

Gavin

I brought my singlespeed into Joe Dalys and they swapped out the cup and cone for a cartridge.

No problem with chainline with non screw-on hub.