Raleigh Technium 480 BB

[duecedawson]

Hey guys,

I'm having a little problem trying to figure out my BB size. My technium has been converted to fixed gear and I purchased this guy:

CRANKSET: http://www.icatchdeals.com/tec9-fixed-gear-fixie-crankset-white-black-silver-160mm-165mm-170mm.html

I measured the length of the BB cartridge on my bike (not the spindles) and it appears to be 73.5cm.

At the bottom of the link above it says it requires a 103mm square tapered BB for the tec9 crankset...my problem is I have no idea what BB size my technium is currently equipped with. How do I find out without pulling out the BB? I want to be able to keep riding while I wait to find out what BB length I need and I do not have my own crank removal tool...I have to call the guy I bought the bike from and he will do it for me.

Thank you in advance.

[duecedawson]

the chainline upfront is 43.5mm

[DaveM]

The BB on your bike is probably somewhere between 103 and 110mm. That's the common size range for road bikes of that period. But you never know.

If your bike has already been "converted", 103 may not be perfect anyway. On a fix, chain line is important. It is not uncommon to have to adjust either the BB spindle length or the spacing on the rear hub to get the crank and cog lined up. It's pretty hard to buy a bunch of parts, throw it all on the bike, and have everything lined up perfect on the first try.

If the current BB is running smooth, I'd say go ahead and swap the crank over and see how it ends up. Measure the spindle before you install it so if you do need to get a different length you can figure out by how much. Note that when you measure the BB, you measure the width of the BB shell on the frame (this should be 68mm) and the overall length of the spindle not including the threads if it has threaded posts that stick out of the end.

Note also that the crank you bought is for a 1/8" chain. Make sure you have the right chain. If the cog in the back is made for 3/32 that will be OK. But you can't use a 3/32 chain on a 1/8 crank.

[duecedawson]

thanks dave. i ended up going with a shimano 107mm BB to try out as when i removed the crank bolt cover, it was held in by a nut, whereas my new crankset uses a bolt to tighten on the BB. I take it as this is a different type of BB?

i remeasured the BB shell and it is 68mm...I was measuring the small bracket things on both sides of the shell as well.

I have a 1/8" chain already. I ran into that problem while doing my conversion (3/32" not going on my fixed hub).