BBSHD measurements

[rilot]

I'm trying to work out how much room I need for the secondary reduction gear and clearance for my chainstays.
Does someone have the exact measurements for the diameter for the secondary reduction gear housing? I'm seeing several different measurements from 60mm to 70mm and it will make a big difference to whether it will fit on my frame.

 

[Kinninvie]

Here
https://www.google.co.uk/search?q=bbshd+diagram&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwijxoa4heTaAhWJzaQKHXNyAPIQsAQIKA&biw=1280&bih=589&dpr=1.5

 

[rilot]

Thanks but I’m perfectly capable of using google. None of those diagrams have the measurement of the secondary reduction gear housing as far as I can see unless I’m being blind.

 

[tommie]

Thanks but I’m perfectly capable of using google. None of those diagrams have the measurement of the secondary reduction gear housing as far as I can see unless I’m being blind.

Yes they do,

and it`s not so much the diameter you`ve to worry about it`s the offset from centre,

click on that link again and try to be a bit more appreciative of others taking the time to search for you

 

[Deleted member 4366]

You can scale it from any of the drawings. Print one off and measure any of the given dimensions to get the scale, Then measure the dimension that you want and scale it.

 

[rilot]

OK, can we start again? I'm not sure where the sarcasm has come from. I'm genuinely asking for help and I've looked at those diagrams. I cannot see the measurement I'm looking for. I just want to know the exact radius of the housing so I can work out what offset I need to clear my chainstays.
As I say, some people on forums have said it's 62mm such as here: https://electricbike.com/forum/forum/knowledge-base/motors-and-kits/bbshd/10736-how-to-order-the-right-bbsxx-kit
Other's say 2.75" which is just under 70mm here: https://www.empoweredcycles.com/blogs/news/101474694-bottom-bracket-standards-and-bafang-mid-drive-motors

I will do the printout and scale method though. Thanks for that.

 

[Woosh]

alternatively, turn the bike upside down, take a picture of your bottom bracket / chainstays and post it here.

 

[rilot]

Will do later this evening. It's a 68mm square taper BB by the way.
I think I need between 5mm and 10mm of chain side offset depending on the exact measurements of the reduction gear housing.
If it's 62mm radius then I can get away with a 68-75mm BBSHD. If it's 70mm then I need 10mm of offset and will need to go to a 100mm BBSHD.

 

[wheeliepete]

It's 68mm

 

[rilot]

Brill thanks. 100mm BBSHD it is then.

 

[Woosh]

Brill thanks. 100mm BBSHD it is then.

why do you want to use 100mm BBSHD with a 68mm square taper BB?

 

[rilot]

Because the secondary reduction gear won't clear my chainstays with the 68-73mm version. This was the reason for the original question.
My bike has wide chainstays (full sus) but a 68mm BB. The BBSHD has a very large secondary reduction gear housing that is not as large on the BBS02/01. With the reduction gear being 68mm in radius I need about 10mm of offset on the crank side to clear my chainstays. If I fit a 68-73mm version I won't have enough thread on the other side to fit the nut.
If the offset was around 5mm then I would have been OK with the 68-73mm I guess.

 

[Deleted member 4366]

Will that offset still allow the correct chain-line?

 

[anotherkiwi]

Will that offset still allow the correct chain-line?

I think we all know the answer to that question d8veh...

The 100 mm version works on fat bikes because the hubs are larger, Almost 2 cm of additional offset will make for an unworkable chainline on anything else.

 

[rilot]

Even with a lekkie bling ring bringing the line back in?

 

[anotherkiwi]

The bling ring makes a nice chainline on a 68 mm motor, you will be getting close to the bad chainline of not having a bling ring mounted.

 

[tommie]

Post a pic of the BB area

 

[rilot]

Will do when I get home from work.

 

[rilot]

OK, here we go.
I've added measurements to the pictures. As you can see, 68mm will impact the chainstay until 14mm offset from the BB. This is just on the BB side of the middle chainring.

This is the chain line with the chain on the middle sprocket. I'm guessing that the chain will be slightly further out from there with a bling ring but not by too much.

 

[wheeliepete]

Another builder is having similar problems to you, have a look at this thread.

http://www.pedelecs.co.uk/forum/threads/battery-question-for-bbshd-and-chainring-question.31083/page-2#post-435684

Bear in mind a Bling Ring will only give you 2mm extra offset over the standard Bafang chainring and the very pricey Luna Eclipse an extra 6mm.