Bottom Bracket Question

I would like to change my existing 'cup and cone' bottom bracket for a modern 'cartridge' type. I've dismantled it and the spindle has the following markings, on one side the Stronglight 'S' and the letter 'C' and opposite the numbers '5' and '18'. Can anyone tell me the meaning of these markings and do they help in sizing a suitable replacement?

The overall length of the spindle is about 118mm and is slightly unsymmetrical. The frame shell width is 68mm and it will be an English thread. I'm assuming that due to the slightly unsymmetrical nature of the existing spindle that I'll need a slightly longer modern (symmetrical) type. Would a 122mm long Stronglight JP400 be a suitable replacement? I don't want to spend too much as it's just a lowish spec bike.

Thanks

Paul

.....should be a straightforward swapover in length if you are changing to a modern cartridge b/bracket using your existing chainset. Normally the longer end of the axle is on the driveside to allow for a double or triple set of chain rings

Griff

Re:

Agreed, I took the old BB axle to the LBS and they sold me the exact same thing as a cartridge.

Very simple to install but you may find the "rivet" that holds cable guide under the BB causes the cartridge to snag when you offer the unit into the shell - mine did and all I did was use a small half round file to smooth it off a little, don't go mad though just the absolute minimum, patience is a virtue here. Grease up the threads, torque it up and away you go!

Ray