Bottom bracket sizing help

[Garythegoose]

I want to convert my mountain bike to electric for my travels across Europe.

I want to fit a bbshd and 15ah battery so I can really open it up on mountain trails.

The donor bike is a cube ltd race 2x 2016. I have put a tape measure up against the BB to see what size it is, but I'm unsure where to measure from, it's a press fit, so do I measure from the edge of the BB, or from the start of the bearing cups?

Here's some photos to give you an idea, and any help identifying what BB I have and what stuff I need to make it fit would be great! It looks around 90mm, and being pressfit, I suspect it's going to be a no go, but fingers crossed...

 

[Woosh]

I suggest you leave the bottom bracket where it is and work around it.
Epoxy some Neodymium magnets to the chainring bolts and mount the cadence sensor to the seat post.

 

[Garythegoose]

Not sure what you mean, or if you are talking about something else.

I want to remove the crank and bottom bracket and install a bbshd mid drive motor to the bike.

 

[Woosh]

Not sure what you mean, or if you are talking about something else.

I want to remove the crank and bottom bracket and install a bbshd mid drive motor to the bike.

sorry my bad. When you said commuting, I automatically thought hub drives..

https://lunacycle.com/pf-41-adapter-for-pressfit-bottom-brackets/

 

[Garythegoose]

I'm not wanting a commuting bike, I want an off road toy!

So I'd definitely need that adapter and a 100mm bbshd unit with some spacers for that bottom bracket? Damn, that's going to add an extra £70 odd to my bill. Stupid shimano and their pressfit rubbish!

 

[peter.c]

I tried to convert a cube In my early attempts and gave up the bb is a pig, and the chain line/angle was odd so unless you are in love with your bike and can fabricate adapt and spend extra cash

 

[Garythegoose]

What problems did you have with the chain line? I didn't consider there might be other problems beyond BB sizing. I can cope with buying a BB adapter and a few spacers to sort my rear cassette angles out. Here's a few photos down the chain, does it look like it could be problematic?

 

[peter.c]

Once you fit the 100mm bbshd the chain line might change depends on spacers needed etc
you will not find out till its stripped and you try and fit it have seen option for 90mm but not recently

 

[Garythegoose]

I see, so it's nothing to do with the current chain line but about how it sits after the motor and chain ring is fitted. So if for example my BB is 90mm,and I fit a 100mm bbshd, that would mean I'd need 5mm of spacers on each side, so my chain line would be pushed away from the frame by 5mm? Or is there more to it than that?

 

[peter.c]

Yes that's the minimum it will be out but it depends if the motor does not foul the stays etc the only sure way is if someone else has done the same bike if not it is trial and error

 

[Garythegoose]

Looking at the stays, it is hard to say if it'll fit or not, it's gonna be close though.
I've had a good look around and can't find anyone who's done this bike model, so it's going to be a gamble. I clearly need to do some research before I go buying anything.
I've found this bb92 to BSA adapter on ebay, it's only about 12 quid which is considerably less than ordering one from the states for £70ish. is it the right thing for my BB?

J&L BB86/BB92->BSA Bottom Bracket Conversion Adapter/Convertor | eBay

Find many great new & used options and get the best deals for J&L BB86/BB92->BSA Bottom Bracket Conversion Adapter/Convertor at the best online prices at eBay! Free delivery for many products!

rover.ebay.com

 

[vfr400]

The things you need to do to fit a BBSHD.
1. Find the 100 mm version.
2. Make a 10mm spacer to go on the shaft on the left side.
3. Remove the BB bearings and replace with equivalent size solid rings with inner dia a to suit motor shaft.
4. Remove the cable guides and run the cables around the motor, which means change that bare cable to a sleeved one.
5. Fabricate a torque arm to stop the motor rotating around the BB

Before you do any of that, you must remove the crank and check by measuring whether the angle of the chainstay leaves enough room for the motors reduction housing and chainwheel. For that you need to consult the BBSHD drawing. As long as you can get the motor reduction housing right up against the BB without it or the chainwheel touching the chainstay, the chainline will probably be acceptable.

 

[peter.c]

Sorry I have to say I do not know if that is the correct one
I always strip the the bb out and look and measure first as suggested above by vfr

 

[Garythegoose]

OK, thanks for the help guys, I'll go off and do some tinkering and see how it goes