Electrifying my Kona Sutra

You’ll remember (possibly…) that last autumn I borrowed an ebike for six weeks (the Nihola Trekking, reviewed here). I liked it, and I liked the difference that it made to my commute even more.

After that came five months of swithering. I knew I wanted an ebike, but which one? At first it was the Bicicapace Justlong, but when fitted with a Shimano Steps assist you’re looking at £4,500, which is only really justifiable if you can get rid of a car. And we couldn’t.

Next was the Kona Electric Ute, which Evans had on a heavy reduction. Unfortunately, they couldn’t find the model they had on sale, and at full price it doesn’t add up, given Kona don’t support the bike with any child-wrangling accessories.

After that I ruled out the double-child carrying ability, and ended up browsing all the various generic hybrid ebikes available through Wiggle and Evans. They were all a little uninspiring—none felt like they offered the versatility of my current “do everything” bike in terms of carrying capacity, comfort, and being-made-of-steel-ness (stop me if I’m getting too technical).

I had a final diversion via the amazing-looking Tern Vektron, which at least offered something different; an ability to fold, whilst retaining reasonable luggage-carrying and utility. On the test ride it was good; surprisingly nippy, despite feeling sluggish. It just didn’t feel quite right, and I didn’t want to spend £3k on something that didn’t make my bones sing with joy.

Finally, I came to the conclusion that what I really wanted was my current utility bike (a 2009-vintage Kona Sutra tourer), with electric assist. It’s a bike that fits me like a glove, has front and rear racks plus a front box, full mudguards, happily hauls the childseat and cargo trailer I already own, and is equipped with dynamo lighting. Plus it needed a drivetrain refresh anyway, after another year of Scottish weather and road grime.

Happily there are a couple of kits that allow you to stick a motor on a normal bike, providing you have a conventional threaded bottom bracket. If you’re looking for crank drive rather than a hub motor (and if you want reasonable assist under the European 250W cap, you are), the options are Bafang or Tongsheng.

The main difference between those motors is how the assist kicks in:

  • The Bafang motors apply a set level of assist (which you can adjust on the move) as soon as it detects the cranks turning. That’s great if you want to do the bare minimum of work and still get full power from the motor, but it’s not subtle.
  • The Tongsheng, by contrast, is torque-sensing (like the Bosch and Shimano motors on almost all off-the-shelf ebikes). It measures how much effort you’re putting in, and applies a percentage on top of that. You have to work more to get the most out of the motor, but it also means you can “soft pedal” in a queue of traffic and not have the motor spear you into the bumper in front.

The Tongsheng arrives on Monday. Along with a host of other bits and pieces (like an upgrade to hydraulic brakes to stop my rear brake cable freezing, and some funky handlebars).

Stay tuned for excitement…


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Looking forward to how it all works and compares with Steps.
Heard of Tongsheng but yet to read a review from anyone using here.

Exchanged a couple of emails with https://ebikechoices.com/ to decide on Tongsheng, and then it was a lucky forum post on pedelecs.co.uk that made me realise they do a UK-legal 48V motor, as well as the 36V one.

I shall report back!

I’m thinking of doing a Sutra conversion with a Bafang motor. While it doesn’t have a torque sensor, this probably means it’s simpler. Since the motor shuts off when you stop peddling or apply the brakes, I doubt you’d rear-end once you’re used to it unless you get really absent minded.

I hope this doesn’t seem critical, but Bafang seems a little simpler, and as a minimalist/essentialist I prefer things to be as simple as possible to perform essential function.

Still running smoothly. Only maintenance I’ve done on the entire bike recently is oiling the chain, and fixing a blackthorn puncture. It is pretty much fit and forget.

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