I converted my Trek Marlin 5 MTB to an Electric Ebike, not totally straightforward but with a little thought it was done over a weekend with a few hours each day.
The issues I had were I never checked to see if the kit was Cassette or Screw on Freewheel hub, and the space I knew would fit the battery I ordered only one of the Bottle Mount Screws lined up the second was too low, I had to mark up, drill the frame and use a Nutsert. These issues sorted the rest was plain sailing until the road test when I found that I could not select 7th Gear, the screw on Freewheel Gearset cleared the frame but was too close to allow the Chain to move over far enough, tbh I adjusted the Derailleur stop and its not an issue now - certainly don't need it.
