Another newbie full of hesitation - advice appreciated.

[R Benny Waered]

Been looking at converting one of my bikes for months now but never feel confident to order any kit - so many gotchas between brake levers to disk clearance and I don’t know if I have a freewheel 9 speed cassette or not or if the bottom crank measurements spec are width or diameter or if the calliper will hit a rear hub! Feel quite useless (despite being able to build a mega PC and swap a head gasket on a car)! Any help appreciated

I really want to convert my heavy semi-downhill Mongoose Teocali full sus MTB and the power assistance will help combat the drag of its comfy MTB tyres. Its mainly for the occasional 6 mile (one way) commute on a bike path (20mph max) and popping to shops a few miles away to get bread/screws! I want to quicken the journeys and make them easier so I don’t use the car as am not half as fit and strong and resilient as I was 25 years ago crossing continents on bikes! I’m also 18 stone and tall and my Scott Sub 10 hybrid bike has my neck craning up too much due to low handlebars and high saddle for me long legs – the MTB riding posture is much comfier. Old age guys!

As said it’s a heavy bike and so am I and I want it to always pull uphill to maintain pace. I also want to contribute effort so 500w sounds right unless a 250w crank motor or geared rear hub motor will do – or can be home tweaked to improve performance? Not keen on a front motor and torque steer/slip. Rear drive cars always work better – keep the front for steering! £600 budget inc any tools to remove cranks etc.

So, would a crank motor work given the fact that the swinging arm moves – I like the fact that you can use gears (will they graunch though as you have to pedal gently to change gear)? Or is a rear hub simpler – but I don’t know if it will work with the disk brake (cable operated) and if my 9 speed cassette is freewheel or not? I thought the freewheel was in the hub not the bunch of gears that slide on and off the hub splines? Battery would need to go under the tube that leads to thed crank. No mounting points.

Enough from me – any advice welcomed as I just don’t see this really happening and I’d love to use the car less.


Cheers

 

[R Benny Waered]

Bump... Maybe I'm asking too much - if so apologies...

 

[vfr400]

The rear caliper never touches the motor if you fit a 180mm disc unless you don't assemble it properly. Nine times out of ten, you need an extra 12mm washer on the axle to stop the caliper adapter from touching the disc. For a rear motor, you need a cassette one. Your rear triangle looks quite stiff, so it might be a bit of a squeeze to get one in. Theyre a bit wider than the standard 135mm.

You haven't chosen the best bike to convert. Compared with the cost of the electrical kit, the cost of a different donor bike wiuldn't have a big impact on the overall cost. A donor with a triangle frame, no rear suspension and 7 speed gears will be much more straight forward. You don't need an expensive donor bike when you have electric assistance.

It's not clear from your photo, but it looks like your bottom bracket is part of the rear swinging arm, so no relative movement between the rear ale and the BB. The only question is whether there's clearance to fit the motor. For that, you'll have to look at the drawings of the motor. It looks like the webs from the front of the BB upwards would prevent the motor, so probably a no-go.

Even if you could fit a motor, you still need to find a way to fit the battery.

To summarise, forget that bike and either buy a ready made ebike or get a different donor.

 

[R Benny Waered]

Thanks VFR - much appreciated.

A minefield so I bought a Cube e-MTB