The restriction only works when being tested.
Two important points: If you have a lot of power, you can always turn it down, but if you don't have enough, you can't turn it up. Secondly, when a 250w hub motor is labouring up a steep hill, it has an efficiency of 30% or less. If you have a more powerful motor that's able to maintain a higher speed, its efficiency could be more than twice as much, so you not only go faster with less effort up the hill, you use less battery energy.
So the restriction would like a limit on how much current the controller is able to put out on the flat to comply with the legal 15.5mph limit speed, but when the demand on the motor is greater (on hills) and you need greater torque (and thus more current) the controller overrides this restriction and proportionately supplies what the motor needs to sustain the speed/power for hill climbing? That's like an intelligent current regulation so you have in effect a 350W-400W maximum output motor acting as a 250W bike under normal circumstances, unless the torque load require the extra power, but you'd still be in compliance with the law on 15.5mph speed?
I'm liking the sound of this a LOT and will do. However, I have no idea what you mean by "dremelling dropouts" or "dishing wheels". I have no experience of working on bikes at all but am willing to learn if I can get help step by step.
I don't know much/anything about crank systems, but isn't one major benefit that you side step the whole issue of gear limitations on hub motors (unless you opt for a heavy/expensive CST motor and custom built wheel)? This would be a prime consideration if you have an expensive bike with loads of gears you don't want messed with?
I think it all depends on your bike as to how easy it will be, if you do a front wheel it really can be as simple as just changing a wheel like it was for me. Anyone can change a front wheel? This forum is FULL of knowledgeable people though and even if like me when I first attempted a self-build, you're full of doubts and questions, they will talk you through it and help you every step of the way. There's some very knowledgeable and experienced engineer types here so you're in safe hands! The best thing is to look at your bike carefully, discuss your requirements and see whats possible and whats involved, before you buy anything..then you can weigh up the cost of going to a bike shop or doing it yourself.. why not just have a go, and if you get stuck or find it too difficult, then see if a member is near you to lend a hand, or consider calling a bike shop?
AFAIK there's only a couple of bike shops capable of fitting these kits properly. I don't think I would trust anybody to do one for me, but it's fairly straightforward.
Most semi-decent forks have 9mm slots for QR wheel, so you have to make them a bit wider for the 10mm wide axle. The axle is actually 12mm diameter (14mm for Ezee), so the centre of the axle ends up lower than it was before. Also the top of the axle is a different shape to the top of the drop-out, which also holds it down a bit. The end result is that the first washer no longer fits in the dimple because it's about 2mm to 3mm off centre. It isn't absolutely essential to make the drop-outs deeper, but you have to make sure that any anti-rotation washers are deep enough into the drop-out to do their job, and the first washer must be properly nested in the dimple, which you can achieve by using a narrow or eccentric washer.
I cant choose, I like both as long as good bikes
I would definitely recommend the front wheel build for people who want to keep their bike functionality in terms of gearing and for ease of fitting... the only downside for me is that it makes the bike look very clearly electric whereas rear hub is more discrete.. I guess the question comes down to whether you will ride the bike without power and if so, do you need more than 7 gears? You should think about your gearing carefully when you do a rear wheel build.and why I like my Bosch powered AVE, it is uncomplicated, efficient, and gets a decent range with a 8Ah battery. No motorised wheels or cabling or brake levers to go wrong..I have had 2 complete wheel rebuilds with hub bikes since I started this and various other issues. Also in something like the neo what can the range be if it hill climbs so well as hub motors are far more demanding on battery, mine certainly is .....
My front hub motor bike has no gear limitations (27 speed XT) the dapush motor is not a heavy monster and it goes over 20 mph and quieter then any SB that I have had.
Bosch powered bikes now at £1000 - £1500 on sale in Germany, so not as aspirational as some may think
I like both but need to be decent spec bikes and lightweight for my needs....hard to choose in the morning which to take out and nice to be able to carry both with one hand on the crossbar. Was out on the Visper this morning, so much fun!
I reckon I can manage the dremelling and wheel/spoke work but the soldering is a skill I do not have, nor the tools. Stood over a plumber whilst he dripped bits all over the floor trying to solder a pipe though ... if that counts. Is this really likely to be a sticking point for a rear-wheel hub fit-out
.. or is the equipment fairly inexpensive and there some way of learning the relevant skills fairly easily ? ? side as against what would be ideal for a £500 outlay with some money in the kitty for tools. Bit nervous about the mention of "torque arms" too - what are they and are they only fitted on front (or rear ?) wheel builds ?
