dogman dan wrote: ↑
May 25, 2018 6:43 am
Don't ruin your favorite bike with a motor. I've typed this advice about 20,000 times by now.
There is an alternative to the situation that Dogman outlines. And that is the lightweight build. It doesn't jibe very well with the notion of pulling a trailer though. Nor will you get regent. But it does seem to be the approach to take if you want your road bike to still look and ride like a road bike. It involves using one of the lighter geared hub motors and a small sized battery pack. It also requires a clear mindset that the rider will be supplying a lot of the power normally and will be using the motor more like a portable tailwind or as a bit of help dealing with uphill climbs and such. It is still primarily a road bike and the motor is there as an assist. Here is one such build.
viewtopic.php?f=3&t=93180&p=1381054&hil ... d#p1381054
The build added 7kg (almost 15 lbs). That still a lot of weight but well short of the 25 lbs Dogman mentioned.
Here's another. The Xiongda YT-06 weighs a smidge more than 3 lbs. The builder is estimating a total bike weight of 22 lbs once done.
... and there are others.
These builds are far from typical. They don't use direct drive motors. They probably aren't well suited for hauling a trailer, and because the small motors are geared, they don't provide regen. IMO, if you want your road bike to still look, feel and ride like a road bike, the above builds show the general approach you should probably take. But if you want a utility commuter that can haul a trailer and so forth, then the typical 50-60 lb converted Mountain Bike with a big direct drive hub motor is probably the best solution. You could try to do something in the middle. But I'm afeared that rather than getting the best of both approaches you'll actually end up with the worst of both approaches.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats