BB axle / Middleburn chainset

Will be removing an old LX triple and Octalink BB and swapping in a Middleburn (RS7 I think) triple chainset.

Last time I did a BB on an old Zaskar it was 68×113. I think my newer (2001) Zaskar is also 68mm but as for axle width, I was going to go with 113 again but the more I look it’s possible the Middleburn needs a little longer axle?

Just wondering if anyone here knows correct width for RS7 square taper BB for a triple x9 setup. I’m assuming I’m still best off going for a UN72?

You’ll be lucky to find a UN72. I had Middleburn cranks back in the day and think it was a fairly standard axle width.

I’ve got one of these from Spa on the commuter and it’s doing fine so far:

https://www.spacycles.co.uk/m16b0s110p3233/FIRST-COMPONENTS-DX-30-Bottom-Bracket

Cheap enough you can get another one if the first turns out slightly off. It takes their 20mm crank bolts:

https://www.spacycles.co.uk/m8b0s173p3395/SPA-CYCLES-Cro-Mo-Crank-Bolts-%28pair%29

That may help, if you measure the chain line of current cranks.

Your muddleburn spider should have identification stamped into it

I’ll have a closer look at the spider. IIRC all the arms say are 175mm.

Yeah only reason I said UN72 was that’s just etched in my memory. Must be 15+ years since I last changed a square taper!

Ah so seems UN55 is the successor to UN52

I always thought the differences between 52 and 72 was that the 52 had plastic cup on one side and wasn’t sealed bearings? But now seems 52/55 does have sealed cartridge bearings so annoyed at myself for buying expensive XT bb’s back then! 🙂