27.5" conversion choices?


New Member
Fiancé is short at 5'1" and hard to fit a bike. She has a Trek Marlin 5 in a 13.5 frame with 27.5 wheels. She loves her bike and is hesitant to give it up for a new electric. So, I'm looking at hub motors for it and wonder what is out there available in a 27.5"? I'm fine with individual components because I'll likely need a very low profile battery option for her bike frame, but if there was a complete kit available, that would be a bonus. Optionally, a small frame bike with 27" step over would work and likely wouldn't cost a whole lot more. Been looking at the Radwagon but am unsure if the stand over is low enough. I see it is spec'd as fitting riders of 5'2".

Anyway, any thoughts would be greatly appreciated. Also know that my budget is around $1500ish.

Ann M.

Well-Known Member
My 'go to' guy, Sheldon Brown, has an excellent expose all about 650B/27.5inch/584mm wheels that should allay any fears you may have about doing a conversion on your wife's favorite Trek Marlin. Since she's already comfortable with the Trek that makes it a good candidate for a hub motor conversion or even a mid drive system. As cool as the Radwagons are, just don't think they can match that tiny 13" frame.

Keith Merson

New Member
I agree with Ann in that a conversion should be no problem. As to kits, there are lots. There are a number of kits reviewed here: https://electricbikereview.com/category/kits/

As you'll see, many of the kits are quite expensive but there are some more affordable choices too. You'll also find discussions about some of the kits here in the forums. Good luck, and let us know what you decide.


Active Member
If you're having trouble finding kits for a 27.5" bike, you could always have a hub motor custom spoked into a 27.5" rim.

Alternatively, you could try putting a 26" kit on her 27.5" bike. The Marlin has disk brakes, right? It'll change the geometry a little, lowering the back, but it might not be noticeable.


Well-Known Member
Rear motor kits and mid drive kits are within your budget if you have some building skills, and don't need insane power levels.

With a mid drive kit, you keep the wheel and rear derailleur but you lose the front derailleur, not that important with a motor.. It weighs about 8 pounds. A light battery will add 6 pounds. It's very powerful, but will run smoothly all day at 200 watt level. Except for the extra weight, pedals like it wasn't there if you turn off power. Doesn't alter the character of the bike very much, In the USA, this kit is currently available as low as $450 and a battery is $500. A year ago, it was $1300 to consider this route.

Hub motor kits can be less expensive. I've been happy with two that cost around $200. These are geared 250W-500W motors. Again they pedal nice, and are light. Rear motors eliminate the possibility of a motor breaking an allow front fork. Geared motors get by with less watts, are light, and also easy to pedal. No experience with direct drive motors, which are more powerful, but harder to pedal. For your fiance's safety, get torque arms for either type of motor.

I have spoked a small motor into a 700CC wheel. Not that hard, but I could have bought a motor kit with 700cc wheel for $180.

I suppose the more expensive kits are more plug-n-play. My kits, I have to understand basic electricity, be willing to splice and solder wires (and have the tools to do so) , use zip ties, and maybe fashion a simple brackets to mount parts.
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New Member
Exactly why I'm anxious for the ShareRoller to reach production and not 'kickstarter' type (Indiegogo) type availability. You keep your good bike and you add e-bike drive when you want it.