electric road bike conversion

My goal is a road bike electric conversion and after saturation by readings, I figure upon a post asking for advice on this build.

From what I can find, there do not seem to be many examples of classic road bike electric conversions and would be interested in any (juicy) threads or (clear) guides of this kind. The objective is an pedelec able to pull a loaded trailer at the same speed and effort as riding unloaded -- a couple hundred watts would probably be close to enough.

Specific criteria include a bottom bracket torque sensor/controller with a direct-drive front hub motor with regenerative brakes. The cycle analyst seems to be the only serious choice for a torque-sensing pedelec conversion. Any leads or recommendations on parts would be great.

Google your title.... SHAZAM!

There is a video or two as well.

A heavy front DD Hub, or any Front Hub that weighs more than 2.5 Kg is something that I would , Not , do.

Older and even late model Road Bikes with Rim Brakes have a 130 mm dropout spacing on the rear, and most if not all rear hubs have 135 mm axle spacing so you would need a newer disc road bike with 135 mm dropout spacing on the rear for a rear hub motor. so that brings you back to the front.
There are alot of people who have bought the little Q100 motor , motor kit.
There are three places that sell that kit I think.

I think people get too hung up on being green and getting back energy with regen. This gets you into heavier direct drive motors, and with front drive, now you make the fork strength propblem even more complicated. While there isn't that much cogging on a reasonable size DD motor, there's still more drag than on a geared unit. And if you want a TDCM BB install for torque sensing, plus the expense of a cycle analyst, well you're welcome to it. For a smaller motor like a Q100, cadence sensing with a good torque sim controller feels like regular pedaling to me. Just my opinion of course, based on limited test riding of commercial ebikes, some with torque sensing and some with very nice DD motors.

Traction might be an issue too. I built a little bike with 20" wheels and a front motor. Q100H. I've noticed some wheel slip on wet pavement starting off uphill. It's something to watch for when Fall comes and there's wet leaves. Not a big deal. On a packed gravel trail, where there will be layers of loose crushed stone, I wasn't happy. I was feeling the front wheel slip a lot more than it does with a regular bike or an ebike with the same motor in a rear 20" wheel. I'll take a different bike now on crushed gravel. A road bike might do better, as the bigger diameter wheel won't be as torquey.

Don't ruin your favorite bike with a motor. I've typed this advice about 20,000 times by now.

There is a real good reason for few road bike conversions. All the advantages of a road bike pretty much disappear when you strap a 15 pound motor wheel, and 10 pound battery to the bike. It just doubled in weight. DOUBLED!!!.

So now that your bike is a pig, it gains more or less nothing from super light wheels, tuck riding position, etc.

and,, 200w is nowhere near enough to tow a heavy trailer up any hill. So the reality for most people is a lot bigger motor, using more power than they thought originally, because of the physics of how hub motors work. They are crazy inefficient when overloaded, and stuck in a high gear ( the large wheel size is like a high gear) they need lots of power to avoid that overload condition.

But I'm NOT saying don't build your road bike. I am saying there is only one good solution, a mid drive type e bike. The bafang 350 watt kit would be the lightest and lowest power, yet when you put your bike in its lowest gear, it WILL still pull your trailer.

The bike will still be a pig though, almost doubling in weight. This may make you wish you had just gone with a regular commuter type bike, for the better tire for city riding on less than perfect pavement.

At the very least, I'd lose the racing handlebar. sit up, and look for the cars trying to kill you if you plan on increasing your riding by 10x.

dogman dan said:

Don't ruin your favorite bike with a motor. I've typed this advice about 20,000 times by now.
[snip]

Click to expand...

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.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=93180&p=1381054&hilit=lightweight+road#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.

https://endless-sphere.com/forums/viewtopic.php?f=2&t=93087&hilit=xiongda

... 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.

I should have mentioned that I am trying to build a vehicle reminiscent of those used in the Sun Trip ride with a couple solar panels stacked on the trailer. I have a dog and would like to have the ability to travel while having a space for the animal under the solar panels. I have a stout frame with cantilever brakes that I think would be a good fit. The riding position with dropped handlebars is good for covering distance and I wouldn't mind it not being light or agile, just streamlined.

There seem to be many 100mm DD front hub motors available and would seem to provide good front-to-back weight balancing without causing more steering issues than front panniers. Though it does seem clear traction would be an issue while pulling a trailer with the lack of weight over the front wheel. But I like the idea of hub motors because they can be swapped out to revert the bike to pre-electrification status. Mid-drive motors are foreboding because they seem propriety, aesthetically bulky and I am afraid of feeling too much feedback from the motor on the cranks.

To cold-set the frame another 2.5mm on either side would not be hard, but there are so many motors that would easily fit 130mm if they did not include the disc brake mounting area. The idea of having a lighter geared motor seems nice, but also less durable and more noisy.

By using a larger motor on the rear you can then pull the dog and trailer , I did mention a small motor in a post above but that was only because you said you want the motor on the front.
Now that people here have told you a few drawbacks of a front motor, I can now think you will be more receptive to forgetting about the front and get a rear hub motor. ( since you now say that you do not want a small mid drive, which would be the best thing in your case of hulling around a dog and solar panels, but you would to keep the motor ) A rear hub is easier than a mid-drive to take off and put the bike back into a peddle only bike after your trip.

So if you still do not want a mid drive, definitely get a rear . for pulling a trailer and a dog, then a motor that is a " low Speed , high torque " motor is what you want. a motor that would do everything you want is the well liked Mac Rear Hub motor, get the high torque one the 12T version. The newest version , when bought with the new version Cycle Analyst V3 also has a temp sensor inside the motor and the CA V3 can be set up to shut off the motor if it starts to get too hot. Something that would be good for anyone who goes up steep hills and pulls heavy cargo.