izeman said:
i heard that the chain line is quite bad as the chain ring is moved far to the right. so grinding away 5mm from the right side would solve three problems:
.) chain line
.) motor mount not touching the frame
.) i can install both rings on the bb
if i ever need to remove the kit i can install a 68mm bb or use a 73mm and a 5mm spacer.
No need to grind anything. It's not really clear from your pictures but you seem to face 2 problems arising from your use of a frame that the BBSxx is not designed for.
That is:
1. your down-tube seems to be an irregular shape and is pressing against one of the motor casing flange bolt mounts on the left side.
2. Your BB appears to be too wide (wider than 68mm anyway).
If you want to persist with this installation I'd suggest 2 simple solutions.
For problem #1, as someone has already suggested, just get a solid spacer that will go in between the curved motor casing and an appropriate contact point on the front surface of the down tube. I have found that a small section cut from a 14mm diameter hull 'bung' (extremely dense rubber) from a yachting supply shop was ideal for this purpose. Just shape a bit to fit the curved tube and glue on with contact cement.
For problem#2, use solid SS washers (or make some spacers from alu tubing) to put into the gap between left-side mounting flange and the threaded motor casing mounts. Trial tighten the BB ring first so you get a reliable measurement of the gap involved and select the number of washers or the spacer required. Do not use the original screws that some with the kit - they will be too short and you'll end up stripping threads in the motor casing (please don't ask me how I discovered this elementary point!) From memory, I think one of the 2 casing threads is 'blind' (that is, not open at it's end). With the flange secured by the BB ring, use a small rod or similar to measure the depth of the blind thread in the casing then add the 'gap' between casing and flange and then the thickness of the flange. This total - minus 1 or 2 mm for end clearance - is the maximum length of the 2 new M6 bolts you need to go out and buy (or cut from longer bolts).
This is a much easier strategy that grinding or cutting anything at the BB and is perfectly secure! Don't forget to use Loctite on the BB ring. Don't worry too much about chain line issues. IMHO it's an overly emphasised 'problem' and can be improved a bit by simply using less cogs at the rear - for everyday road use with the BBSxx you only need 3-5 gears anyway. Just set the derailleur stops to use the highest few gears on the cassette or freewheel (starting with the smallest) or - if you need your low gears for hills - just reconfigure your cassette with fewer 'smaller' or 'in between' cogs using appropriate free hub spacers to move the combination you end up with further to the right side of the wheel and set the stops on your derailleur as needed. I've used both these approaches quite satisfactorily.
Savvas.
Ps; I'd add - and I know it sounds a bit 'school-teacherish' - that the installation of the BBSxx kits will obviously be much simpler of the frame chosen is one the kit is designed for. There must be millions of such frames and bikes available - new and used - on the planet. Apart from an old Moulton APB, the kit will fit every one of the dozen or so bikes in and around my bike shed. All road or older MTBs to be sure, but all suitable candidates! Just a thought...
) and the bike seems to be the perfect candidate for the bottle mount battery.
