Great thread. I thought I'd update this in relation to the BMC motors (we are a relatively new dealer of those, but have contributed ideas to BMC for a new high-torque version for the cargo/sports utility bike market that is coming soon).
I'm going to write this up and make it into a table on our website, since it is confusing due to all the different names people use, and the new versions coming available.
Right now, there are 4 BMC bike motors available and/or soon-to-be (these are the 4 that BMC has made us aware of, I cannot guarantee that there aren't other versions around, but I suspect I would have heard about them if there were).
1. The original. Labeled "250W" on the sticker, official BMC part number 14110-1. Despite the label, BMC claims this is their "400 watt" motor. We call it the V1 (version 1). 5:1 gear drive. At 36V, this one will top out unloaded at 25mph, but with a rider, more like 22-23 mph while pedaling (using the BMC "25A" controller). Max power it can safely accept is around 48V/20A. It is very similar to the eZee motor. It uses the nylon gears. Despite some bad rap for these controllers, we've so far had good experience with them, having put two through fairly extensive use and abuse. BMC claims they upgraded the FET's a while back. They are very waterproof (everything is potted). Their main problem is that they can only do 36V at 22A (despite the 25A label, I have never seen above 22A). I will soon test one with 48V, but I hear rumors that it will fry them.
2. The new "600W". The latest, which has just appeared in the past few weeks, is their higher-speed geared motor. Official part number 14110-2. We call it the V2-S (version 2 speed). The windings are heavier and can accept substantially more power than V1. Spoke holes are bigger, to readily accept 12 or 13 gauge spokes. In our experience, this produces less torque than the V1 at identical power levels. That observation was confirmed by BMC, since they have wound this for speed over torque. But, since it can be used at higher amps and/or volts, then if paired with the appropriate battery and controller, it will still produce plenty of torque, more than V1, when run at higher power. Top unloaded speed at 36V is around 30 mph. At 48V this will be more like 40mph. Practical speed with rider at 36V (and > 30A controller) is upper 20's. The very first batch of these we got had weak clutches, but a batch is on their way with stronger clutches. The motor still uses nylon gears, for noise reasons. BMC apparently tried metal gears and it was too noisy. We are building them up in Sun Rhyno lite wheels in a 1X pattern with a spoke twist at the cross, for strength. I am using one on my Yuba Mundo, and have carried up to about 150 lbs of cargo in addition to my 200 lb rider weight. So far, the wheel hasn't budged.
3. The newer high-torque "600W". Not available yet, but very soon (possibly by early December, if all goes well). We requested this from BMC for our customers who have heavy bikes or big hills to climb. It uses the same internals as the V2-S, but is wound for a bit more torque - 35% according to BMC. The official BMC part number is the 14110-2T. We call it V2-T for short. It will be a bit slower than the V2-S, probably much more like the V1 speed-wise. But with the bigger, beefier windings, it will be able to accept a lot more power for climbing than the V1. I can post more about them as soon as we have them in hand. The first limited batch is already spoken for between ourselves and another dealer. We will be building these up in very heavy duty wheels for the sports-utility bike crowd, using butted Wheelsmith spokes designed for Downhill mountain bikes, and Sun Mammoth rims, also designed for downhillers.
4. The fabled "1000W". I do not have one of these - supposedly a few are now in testing. This will be an ultra high speed motor, non-geared. Rumors from BMC of it being around 40 mph at 36V, unloaded. That would make it very similar to the Forsen (high speed, low torque, but the BMC will be lighter weight). I do not have the part number, but could guess it is something like 14110-3... We'll refer to these as V3 motors.
All of the above use the same, relatively compact BMC outer case that can fit a 7 speed freewheel and 6-bolt disc brake. The V2 series are just a tad heavier, due to the extra copper. Nylon gears are a potential wear item, but are replaceable.
I hope that helps clear up some of the confusion about the various BMC motors floating around. There are a lot of different names for these from different vendors, which does not help. BMC themselves only use the model numbers, which are a bit too obtuse for most of us to remember.. (at least people of advanced age like myself). At the risk of just introducing more confusion, we are trying to keep it simple with the V1, V2, V3 numbering scheme.
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