Hardtail build - right track ?

[KirstinS]

Hi all

I have pretty solid experience with hub builds and pretty good with the electrical side of ebikes. Far less capable, I mean far, on the mechanical side

Designing a new hardtail. I've a 29er steel frame and front forks already but free and not beholden to them.

I'm looking to build a alfine 8 driven , bbs02 250w mid drive at 36v

I know the Bb is ok, from research at least as 68mm. What else is key to consider ? Special chainrings? Weird spacers ?

I already have various 36v packs of quality and decent c rates.

It is the mechanics of a mid drive and alfine that I'm struggling to see the challenges as it is new ground for me. Mtb with alfine are rather specialist as is. Thin steel tange or Reynolds frames also. But I like them !

Any help appreciated - assume my mechanical knowledge is bad as it really , really is !

 

[Deleted member 4366]

I think the main problem is the chainline. The chainwheel needs to be more or less in line with the Alfine sprocket. With a derailleur bike, it's no problem because the derailleur guides the chain, but with no derailleur, the chain will jump off if it's too far out of line.

 

[KirstinS]

Thanks, so is that a matter of frame design, wheel build or funky chains wheels /spacers on the drive?

 

[KirstinS]

Or simply a chain tensioner?

 

[Deleted member 4366]

You'll have to take measurements fom the centre-line of your bike to see how they will line up. The BBS01's chainwheel is supposed to be 50mm from the centre.

 

[anotherkiwi]

While procrastinating on my next move I came across a chain tensioner for the Alfine which can be used to improve the chainline.

 

[Sherman]

Alfine chain line is 42mm, so it would be really best to move the Alfine sprocket outwards. Somebody must have done it, google Alfine 8 MTB chain line (as I understand BBS02 uses MTB 'standard' chainline of ~50mm).