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I got this old road bike that I bought for $20 and fixed up a bit. I'm having to use it for a very long commute in the meantime until I can get other transportation so I was looking at a cheap electric kit solution. The mid drives are too expensive because my budget is only about $400 so I was looking at hub drives but all of them I find are 26".

My bike currently has 23. The side of the tire says [700 x 23C]

If I get one of these 26" hub wheel kits will it fit my bike?

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ANSWER No. Your bike has a 700 wheel. A 26" wheel is too small for your frame and so the brakes won't reach the rim.

I doubt you'll get a decent kit for $400, the lowest I'm aware of is $500 and has a pretty small battery - http://www.electric-bike-kit.com/hill-topper.aspx

A hub wheel kit might just be a hub motor, with spokes, and battery/charger/controller. That could work but you'll have to rebuild the front wheel onto the new hub, which is fiddly but not impossible. A shop would charge $100ish to do the same.

Electric road bike wheels tend to be uncommon because as the wheel diameter increases, the top speed goes up but the torque goes down. So an electric 12" wheel can smoke rubber but tops out at 10 km/h whereas a road wheel would be slower to wind up to speed and may not reach the limiter.

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It's quite unlikely. The axle length (hub spacing) will probably be rather different.

Here's a list of axle lengths. The same page also discusses how you might get away with it on a steel frame with quite a lot of effort.

Then you get onto the wheel building, which isn't easy and had to be good for electric wheels with their greater stresses. The 26" wheels wouldn't reach your brakes, so I assumed you use the hub motor and your existing rims with new spokes.

  • And you may want some brakes, which you have to shim to work if you're lucky. – Batman May 7 '16 at 7:14
  • @Batman I was assuming that the hub would be built into a 700 wheel hence the last paragraph, but I'll make it more obvious. – Chris H May 7 '16 at 7:20
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The 700c wheels you have correspond to an inch measure of 27" to 29", depending on tire thickness. The 23 on the tire refers to the tire width, in millimeters, indicating that these are skinny road tires.

Never mind wheel size including tire, though, the critical measure is the rim diameter. 700c road bike wheels have a 622 mm diameter. Wheels under the 26" designation (common on mountain bikes) usually have a 559 mm rim diameter.

A bicycle frame with rim brakes, designed for 622mm rims, will not accommodate a 559 mm wheel. The brakes will be incorrectly positioned, making them useless.

The cheapest way to get those intended hub drives installed into something resembling a bicycle is to get a different twenty dollar bicycle: one which takes that size of wheel.

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