Round bobweights for crank balancing (18).

Checking out the strength of zip ties at 1300 rpm. If the bobweights aren't round then the mass isn't distributed evenly around the journal meaning that whatever mass you think it is, it's not. This is a stock 2nd gen 6G72 crank, bobweights each within 1 g of each other. I managed to get lead wheel weights from the local tyre shop for free, melted them. Made a mold for casting them and got all of the required weight into a diameter of 93mm which is the same diameter as a stock big end at it's extremities. A stock big end cap with a hole in it but with an added bolt = 210g. Add 200g of lead and it becomes 410 g. Add a bearing at just under 15g and you've got 425g. Tie 2 of them together for 850g including the zip ties. As it is it gives a fairly good balance, but I'll be fine tuning it a bit. It's easy to fine tune with magnets. Got a stack of them, can stick them on the crank, move them around easily to check imbalance. Next is to remove 5g to each of the 12 halves.

[@1magnit]

Given that it's a 76mm stroke and 1300 ish RPM, how fast is it travelling when it lets go?

[@1magnit]

76mm x pi x 1300 x 60 / 1000 / 1000 might give km/h? only 18?