Help with bottom bracket size for Bafang BBSHD

[sgibbins]

Hi all,

I've got a Carrera Vendetta, which I'm desperate to convert to an ebike. I'd like to try a mid drive kit this time rather than a hub drive, but have come a little unstuck with what to get re: bottom bracket size.

As far as I can see, the bottom bracket on the Vendetta is 'Sealed bearing, 73x127mm' - would that mean I need to get a 73mm Bafang kit?

I also have no idea what type of bottom bracket I have - could someone please advise me which bafang to get, as I was hoping to get cracking before Christmas

Thanks in advance!

 

[Deus]

https://endless-sphere.com/forums/viewtopic.php?t=80319

 

[wheeliepete]

Post some photos of your BB with the bike inverted showing the chainstay on the drive side. A 68mm should fit your 73mm BB as long as you have enough clearance for the sec. gear casing. If not, then it's prob. not viable as the 100mm with spacers will cause chainline issues.

 

[sgibbins]

See attached. As far as I can see, the BB is just over 100mm. I have no idea whether it is threaded or not - can I tell without taking it apart?

 

[peter.c]

I checked a vendetta out in Halfords, I think the chain stay could be a problem so did not buy one it had a single front your triple might be ok

 

[sgibbins]

I checked a vendetta out in Halfords, I think the chain stay could be a problem so did not buy one

Okay, what makes you say that? Chain stay getting in the way?

 

[peter.c]

The motor will be up against it and the newer single chain wheel was tiny yours looks like it is built with a different frame
The halfords site is odd shows the bb at 73mm

 

[sgibbins]

I'll do some measuring and figure it out. Any suggestions for a fat bike that would work as a donor for a bafang conversion if it doesn't work out?

 

[vfr400]

Your BB is 100mm, not 73mm. That's why your chainwheels are well clear of your chainstay.

 

[wheeliepete]

As peter.c says it may be ok, but from your photos your BB is deff. more than 73mm, so you will need a 100mm HD kit. You are best to strip the BB and take some accurate measurements to ensure you have the clearance on the chainstay. I will post some tomorrow when I'm home.

 

[sgibbins]

Super, thanks everyone. I assume that I could buy a 110mm bafang and simply add spacers to get a tight fit, as well as to avoid the assembly pushing on the chainstay?

 

[peter.c]

The more spacers you add, the further the chain line goes out the more problems you cause

 

[vfr400]

The more spacers you add, the further the chain line goes out the more problems you cause

But the spacers go on the left side, so don't affect the chain line.

 

[wheeliepete]

This photo may help you understand the clearance you need. You must have around 65mm between the centreline of the BB and the chainstay. This frame has around 64mm, so you would need 1-2mm spacer on the BB for the HD to fit.