EricJ

I want to add a pedal-assist front hub motor to my 2002 RANS V2 for a little help pulling a small trailer up hills.

The problem I'm concerned about is fork width. At the lugs it is 4" (102mm) wide and tapers to about 3.25" (83mm) at the point where it bends. I've seen very few dimensions for the hubs I've looked at, and don't know if any of them will clear the existing fork.

Has anyone successfully adapted a front motor? Is there a replacement or custom fork that might be wider to accommodate a hub motor?

Eric

Sianelle 

It might be worthwhile to telephone some suppliers to get hub dimensions, but my very first electric assist tricycle was an old 1960s Raleigh that I fitted a 250watt front hub motor wheel into the original Raleigh forks. There wasn't much room for the hub, but it did fit after a little messing about. So I guess if I could get a modern electric hub motor into a set of narrow Raleigh forks you won't have too much trouble with a bike that has 4 inches to play with between the lugs.
Unfortunately I don't have a photo of my old Raleigh trike with the hub fitted, but I used it to deliver supermarket flyers all over this country town where I live and let me tell you all that paper weighs heavy and there was a hill or two to climb as well.

Abneycat

Standard dropout compatibility for a front fork hub motor wavers around 100mm. If you've got a steel fork, anything within 5mm is an easy and safe fit, and there's a tolerance above that if done correctly.

Here's an engineering diagram of a Crystalyte 4 series hub motor, showing all of the dimensions you might need to know in mm. Many other hub motors are of similar dimensions, hope this is helpful to you.

https://ebikes.ca/store/diagrams/M400F.pdf

EricJ

Thanks Sianelle and Abneycat.

The drawing was very helpful. Sometimes it's difficult to formulate the right questions without a little education first. The drawing gives me a standard of comparison to ask the right questions of other manufacturers as well.

With gas around $3.45/gal now, I'm using the V2 more and more for 'round town hauling. The electric assist would make it that much more practical for day to day use.

Thanks again for the help.

Eric

jerryt

Eric,
Heres a pic at https://66.216.117.91/Brushless_Kit_B...p/us-bl-36.htm for forks. EDIT: The pic shows 3.75 which was not enough clearence on my bike.
I bought a Wilderness Energy front hub motor and had to jack the forks to 4.25" (from 4" +/-) for fit. The primary problem was fitting the axle in the drop-out slots whereby I had to file the motor axles.

EricJ

Thanks, Jerry. The illustration agrees with the dimensions abneycat sent. I actually have 3.25" clearance at the narrowest point, so I should have sufficient clearance for their BL-36 or the Crystalyte.

One of the first sites I found said I needed a minimum of 3.75" at a point 5 inches above the axle which is why I first became concerned and wrote my post. It looks like the Crystalyte 400 series will drop right into my fork.

Now for the hard part. Actually pulling out the plastic and placing the order.

Eric

Abneycat

EricJ, i'm curious, which model are you going to go with for the 20" wheel?

EricJ

Well, it's still early enough to convince me of almost anything. But I'm leaning toward the Crystalyte 405. At the site you recommended under Purchasing Online, they list their recommendations for each wheel diameter. For a 20" they recommend a 405 (also a much more powerful 500 series I have no interest in). At 36 volts, with a loaded bike, they say it will sustain 20 mph which is all I care to do. If you go to their simulator, it shows how this motor would perform.

https://ebike.ca/simulator/

The sim is showing maximum power at about 440 watts which correspond to about 12 amps at 36 volts, well within the 20 amp controller's range, and not all that demanding on batteries.

I fly electric RC airplanes with brushless motors, similar controllers and lithium poly batteries. I have AIRPLANES with specs like this. Some of them draw 35 amps, though I am only running 3 cell lipos at around 12 volts.

The ebike.ca site is a wealth of information. Though I am leaning toward the 405, I am using that information as a standard of comparison for others as I discover them.

Eric

Abneycat

Ebikes.ca (Renaissance bike company) is probably my favourite source yet. They know a lot, and they share it well. I just noticed that their website has had an update now, with some geared motors on clearance, info on new batteries, and they're now stocking eZee kits as well.

The 405 on a 20" wheel sounds pretty good to me. The 406 would also do well if you wanted more torque at a comparative power output, either one is a good choice for sure.

Good luck on your progress!

EricJ

Yeah, I agree on the 406. Both looked good on the sim. I am more interested in torque for help on hills than top speed, in fact that's one reason for putting the motor on the front with the 20" wheel instead of on the rear 26". I'm 65, and I think the extra help on the hills will encourage me to use the bike for more errands in parts of town that are hilly. Besides, I live on a small hill and that is ALWAYS the last part of every trip and it always occurs when I am tired.

Next research job is batteries. I use lipos for the RC planes, but have been considering the A123 technology for them. they charge much faster and are a little more tolerant of slight abuse. I know some ebikes are using them and I think they would be a great choice. Batteries are going to be the biggest expense in this project, but once I know where I want to go with them, I'll buy everything and get moving on it.

Thanks for all the information. I enjoyed your discussion of solar chargers in another thread. I had been rolling that idea around in my head and came to the same conclusion that there was no compelling reason to do it unless you just want to do it for its own sake. So I can scratch that line of inquiry off my list.

Eric