More bottom bracket queries!

[hercule]

I ride a Hase Kettwiesel recumbent trike. As currently set up it has a Shimano chainset with an external bottom bracket, but the cranks are 170mm and I want to swap to a TA square taper triple chainset with 150mm cranks. I’ve got a dodgy knee and all my other laid back machines have short cranks so I have to swap!

Unfortunately a standard cartridge bottom bracket won’t fit, largely because the Kettwiesel uses the bottom bracket shell as a mounting point for various bits managing chain tension and the protrusion of screw thread and securing nut fouls the shell of a cartridge BB.

Other than a olde fashioned cup and cone BB (of which only very cheap ones seem available as-new now), is there anything else available? I was hoping there was a cheaper copy of something like the TA Axix BB as the genuine article is rather pricey. On the plus side the BB is well away from any front wheel spray so it’s unlikely to get regular contamination. Chainline’s not critical either as the rear axle is a long way away! It just needs to be long enough to accommodate a triple chainset and there’s no chainstays to worry about either!

[Brucey]

in such cases you can often rework the arrangement so that the parts that are bolted to the BB shell are secured differently, e.g. using a bolt with a shallow head, put through from the inside. In this way you can often make room for a cartridge BB unit.

The other thing that makes a difference is the size of the BB unit; if you can find a NOS BB-UN72 you may find that it is slimmer in the centre than current units and this allows more clearance inside.

cheers

[NickJP]

Alex's Cycle in Japan sell the Dixna 110/74 BCD crank in lengths from 130mm and 170mm. With one of those you can continue to use the external BB bearings:

https://alexscycle.com/collections/cranks/products/dixna-la-crank-arm-set-130mm-to-170mm

[hercule]

Running a domed bolt from the other side - yes, that should work!

Thanks also for the tip about the cranks - I haven’t heard of that brand before




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