BSA square taper bottom bracket compatibility with Swytch

[Christyt999]

Hi there,

So I'm a non expert looking to convert my Specialized Crosstrail with a Swytch kit.
My bike's got a Square taper BSA 68mm BB.

They say you need 20 splines and ideally 7mm gap between frame and pedal and the pedal sensor needs to fix on to square part.

Mine looks like pics attached - and I'm thinking it 's not compatible as is?
They also say you should have 20 splines. On mine the splines are not even small ones all the way round - they have 12 small ones and 4 large gaps - which also seems incompatible.

So my question would be - would it be pretty simple to change the BB so it would be compatible. If so - would something like Shimano UN300 square tapered bottom bracket - be suitable. It is 68mm and 107mm length which Swytch recommends.


Eternally grateful for any expertise you can share to help me sort this out.
Many thanks

 

[sjpt]

Why Swytch? They are overpriced, and their post sale support seems rather hit and miss.

Have you considered the cheaper better quality kits with much better support from Woosh (https://wooshbikes.co.uk/),
or even Yose (https://yosepower.com/)

 

[Christyt999]

Thanks but I've already partially ordered and paid!

 

[eas2lv]

The BB is relevant only if you want to use the so-called "integrated pas". The conventional two-piece PAS involving a magnetic ring and a separate pick-up sensor will fit on your bike. No need to change the BB, just ask for the two-piece PAS instead (standard or universal).

 

[saneagle]

Hi there,

So I'm a non expert looking to convert my Specialized Crosstrail with a Swytch kit.
My bike's got a Square taper BSA 68mm BB.

They say you need 20 splines and ideally 7mm gap between frame and pedal and the pedal sensor needs to fix on to square part.

Mine looks like pics attached - and I'm thinking it 's not compatible as is?
They also say you should have 20 splines. OnView attachment 62073 mine the splines are not even small ones all the way round - they have 12 small ones and 4 large gaps - which also seems incompatible.

So my question would be - would it be pretty simple to change the BB so it would be compatible. If so - would something like Shimano UN300 square tapered bottom bracket - be suitable. It is 68mm and 107mm length which Swytch recommends.
View attachment 62074

Eternally grateful for any expertise you can share to help me sort this out.
Many thanks
View attachment 62075

As long as you have the BSA/Shimano type BB you'll be OK. In the worst case if something doesn't fit you can buy a new BB from Halfords for about £10 for whatever length you need.

 

[Nealh]

Looks ok to me.
Looking at your BB it appears to be fine and a 20 spline PAS will fit . All that is different is the larger gaps on your BB are missing a piece of material from the middle , otherwise one would have 20 equal castellation for the PAS spline to sit in to.
The push in all-in-one PAS will still fit and utilse the BB castellations to firmly contact and stay in place. The castellations simply stop the PAS outer part from rotating , whilst the PAS inner part grips /locks on to the BB axle to rotate when the cranks are turned.