Re: The *BEST* Solution for "THE" tensioner/pulley
Yes- tensioner on the pedal side-
THEY CALL IT A "DERAILLEUR"!!!!!!!
This takes care of the tensioning between the two chains at least- And you have a pedaling choice- at generally no more weight than the standard tensioner- which in fact is HEAVIER than a lot of derailleurs. (of course the extra cogs add some weight too)
Like others have said here, you still may have some allignment problems- this can usually be anticipated by simply sighting before installing- is the back sprocket behind the motor sprocket? remember axle spacing is possible too.
And some chain rear dropouts may unluckily not allow the correct motor chain length like Veniceboy has said- but probably will more than not.
Mountain bikes may make good builds, but so many have VERTICLE DROP-OUTS (like criterium racing bikes). Verticle drop-outs leave no margin for chain adjustments.But the best bikes for build, at least as far as chain tensioning, are ones with long horizontal dropouts- some may even have screw adjustment, like Campagnolo road dropouts.