It is very good. I had a couple of problem. 1. My bottom Bracket was 73. So I needed longer bolts than they supplied. I purchase a 5 x 20mm bolt. Also needed about 5mm of spacers (4 small washers). Be sure to read about this. If you have a 73mm bottom bracket you will need these. 2. I also purchased the special tool bottom bracket tool so I could torque the the locknut down properly 30 lb ft. I highly recommend that you Torque thislocknut and the Crank arms to the correct torque. You may also need blue locktight for a few parts. The only other issue had to do with the connectors between the battery. If make sure you have connectors. I purchase the ones xt90s connectors: http://lunacycle.com/batteries/connectors/xt90-s-connector-set-with-pigtails/ These seem very nice. Now that it is all done it is working great. Will probably purchase a 2nd one soon. Should be easier the 2nd time.