Axle length for cottered chainset

[severnthheathen]

Help and advice please folks. I'm intending to fit a Williams cottered chainset to my Viking build. I'll be running a single ring at the front and a 5-speed block at the back. The rear hub width is 120mm OD. The bottom bracket shell is 68mm. How do I calculate what length and configuration of axle I need to achieve a good chainline.

 

[Spokesmann]

With some of my old Carltons Ive found the old raleigh BB spindle came in two lengths, measurements escape me at the moment as I don't have one of the bikes here to check at the moment. The BB shell would be pretty standard, Im assuming you have the cups for the item? It would probably be english thread 24 or 26tpi.

 

[severnthheathen]

No, I don't have the cups or anything else yet. I'm sourcing the chainset at the moment - then it'll be the bottom bracket kit and cotter pins. And then...

 

[Spokesmann]

No, I don't have the cups or anything else yet. I'm sourcing the chainset at the moment - then it'll be the bottom bracket kit and cotter pins. And then...

Ive found cups, balls and spindle as groups on ebay before. May be worth checking the threading on the BB shell.

 

[Iwasgoodonce]

Do you mean a chainset axle length such as this? If yes, will try to measure later.

 

[severnthheathen]

Yes, something like that. From a bit of research I've done it could be 125mm, but I'd like to know what yours measures if it's not too much trouble.

 

[originalshinkicker]

Not sure of the axle length but your front chainline measurement, centre of BB shell to centre line of chain ring should be approx 42mm (according to Sutherlands Guide for Mechanics) - that is for a 68mm shell with a 120 OLN rear end. Having that 42mm dimension may help determine the overall length of axle, so 125mm sounds reasonable.

 

[jon w]

There are several lengths. The two basic ones are for bikes with or without chainguards. I'll measure mine.

 

[Iwasgoodonce]

Well, I think statistically mine is what you would call an outlier!

I have had to measure it in situ. I couldn't face the whole cotter pin misery again! I managed to get the micrometer on it though and it came out at 144.5mm.

That is total length end to end.