hub motor design & torque

[coops]

half? Thats optimistic!

 

[coops]

Do the internals of the "puma" motor shown in this thread (scroll down a few times) look familiar?! nylon gears, but I've seen that design before on images shown here!

So, a useful motor with plenty of torque? Seems to do around 23 mph in 26" wheel at 37V, with torque off the scale - at up to 35A depending on the current limit, I make that an almost extravagantly high peak power of over 1260W!!! at 20A limit its still a decent 700W. I wonder if such a motor could be used in a home-build project and somehow incorporate a "limiter" to make some attempt at on-road legality? say limit to 24V, would give around 15-16mph max?

The hill-climbing sounds prodigious - 20% at 12mph on the bike in that project, though at 48V.

Long thread that build, but some interesting video links near start and around p15 the bike's first trips.

Range is around what we expect at ~20mph+ compared to other bikes capable of that, 20-30 miles on a 54V 9Ah ~486Wh battery at 21-22mph.

Now I'm thinking big, fast charging Li phosphate and 36-72V controller ...
just how best to mount batteries...

Stuart.

 

[flecc]

No, it is a different motor Stuart, similar but definitely not the same. Many of these are similar of course, in line with what I was saying a few replies before about not many best ways to make electric motors. With each advance they tend to follow each other. Could be the same manufacturer of course, but the Puma must be more powerful if Mark at Team Hybrid is correct about not using them in alloy forks.

He did have some Quando motors in stock as well, but was having difficulty getting them working some while ago. Probably the colour code problem again.

The only thing with these motors that Mark and the other performance biased people offer is the the problem of short range. Their figures are usually based on flat running, but that can halve if used in a very hilly area as in my location.

Make good fun bikes though.
.

 

[coops]

...it is a different motor Stuart, similar but definitely not the same.

Yes, that's what I meant - similar in design: you're right, I guess I shouldn't be surprised to see that as you say, but I was encouraged to see the same design after your positive comments on the Quando/Torq motor, and seemingly good performance from it too. Do you think this one may perform similarly and would you consider it a "good" motor i.e. design and build, from what you can see? What difference would nylon, not metal, cogs make? - I seem to remember it being said that nylon is actually very good for cogs, durable and smooth/low friction or something?

I see what you're saying about range in hills (the motor gearing seems to be for speed, with lower speed torque needing higher current & hence power output as a result) but do you think its a reasonable compromise for mostly flat with occasional hills, possibly quite steep? Also, if fast charge batteries & portable charger are used, I'm hoping that running down the charge is less of an issue (stop for a cuppa & recharge batteries too ).

Do you think this might qualify as one of the better kits (I read what you said before about kits vs mods, given the fairly moderate motor weight (4kg/8lbs?) and seemingly ok quality, if fitted to a suitable bike e.g. rear-mounted, and battery can be suitably carried somehow? I'm still open to the possibility of modifying an existing, ready made ebike, but to be honest that does seem rather more fiddly in some ways e.g. fitting freewheel gears to rear motors lacking a means of attachment for instance, and you don't get to choose your components specs like motor, wheel size, battery type/capacity etc. exactly as you want, although of course the battery mounting issue would be largely solved for you . I'm unsure if the freewheels on these kit motors are exchangeable if required: if not, thats a mark against them since the provided gear range may not be ideal...

Make good fun bikes though.

Yes, could be fun if it all comes together!

Stuart.

 

[flecc]

The build quality looks ok Stuart, and the design is so similar to the Quando motor I'd have no hesitation in using it if I wanted something with this sort of power. It's heavier than the Quando motor (3.5 kilos built in the rim) so the extra weight is from more magnet, pole and coil material for that higher power.

Rear motors for freewheel use are normally supplied without freewheel, just the thread, so you just choose from the list I mentioned before and screw it on yourself. I've not heard of kit motors supplied with one fitted. But do make sure the motor has a standard freewheel thread and not a BMX thread. There are no multi sprocket freewheels on the market for the BMX thread which was designed for single sprocket use only.
.

 

[coops]

Thanks for the tips flecc . I seem to recall seeing a motor for sale with freewheel attached, possibly a crystalyte 5 series (now those are heavyweight motors! around 12kg I think?!!) but that could have been for "illustration only" or an exception, but at least it can be seen, as you say, that the motor can take a freewheel.

I still think a lower geared motor may be more versatile, but so many are higher geared: the crystalyte 5305 seems less available than the higher speed/ lower torque 5304, yet many seem to build the 5304 into 24" wheels, rather than 5305 in 26" say? Since they're mostly run at high voltages, speed would never be a problem anyway... .

Stuart.

 

[flecc]

The freewheels are dirt cheap anyway Stuart, so if one was supplied you could always sling it if not suitable, as long as the thread was standard.

The Shimano Cadet and Cadet Megarange are just £9.99 from Wiggle.
.

 

[coops]

Thanks again flecc now to get my frame stretching boots & battery-case making hat on ... before donning a full face helmet by the looks of it

Stuart.

 

[coops]

One point fundamental to putting a hub motor in a larger wheel is the geared reduction for the correct rpm in that wheel: I'm no engineer, as I've said before, so I'm wondering whether there's any possibility that a hub motor geared for & used in 26-28" wheels should be less efficient than a less gear-reduced motor in smaller e.g. 20-24" wheels??

I guess motors in current 26" wheel ebikes show that they can work efficiently?

EDIT: 28" just seems a bit... big! might there be extra strain on or losses through the spokes at that diameter? I just can't help but think there's something intuitively amiss about hubs in 28" wheels? Though I suppose the Torq works quite well, is there maybe a reason why it was made with a highgeared motor...?

EDIT: answer here!

P.S. Thanks for the 5-star thread rating, whoever it was that voted (it wasn't me, honest!), it was a nice surprise, though I'm not sure it warrants it and it seems such an obvious subject - but maybe that's why then! Thanks anyway .

 

[flecc]

Any vehicle's motor has an optimum gearing related to it's purpose. When that is departed from, efficiency drops. That's why the Torq is not much good at hill climbing on power only, and would be an equally useless tow bike with a real load or up a slope of any sort, it's too high geared. But that gearing enables the motor to run the bike to higher speeds if aided sufficiently by the rider and when conditions are favourable. Any weakness of the rider, and/or worsening of conditions, and the inefficiency becomes obvious.

In other words, rule gearing changes out completely from any plans for best results. Just use a motor in the wheel size it was designed for, or be prepared to make good the deficit using your own muscles if you gear up, or accept the loss of speed if you gear down.
.

 

[Aero]

Do the internals of the "puma" motor shown in this thread (scroll down a few times) look familiar?! nylon gears, but I've seen that design before on images shown here!

So, a useful motor with plenty of torque? Seems to do around 23 mph in 26" wheel at 37V, with torque off the scale - at up to 35A depending on the current limit, I make that an almost extravagantly high peak power of over 1260W!!! at 20A limit its still a decent 700W. I wonder if such a motor could be used in a home-build project and somehow incorporate a "limiter" to make some attempt at on-road legality? say limit to 24V, would give around 15-16mph max?

The hill-climbing sounds prodigious - 20% at 12mph on the bike in that project, though at 48V.

Long thread that build, but some interesting video links near start and around p15 the bike's first trips.

Range is around what we expect at ~20mph+ compared to other bikes capable of that, 20-30 miles on a 54V 9Ah ~486Wh battery at 21-22mph.

Now I'm thinking big, fast charging Li phosphate and 36-72V controller ...
just how best to mount batteries...

Stuart.

Hi, I don't know all details of this thread, however there is a very good e-bike
controller-data logger that you could used as a "limiter" that allow's you to control current, top speed, and cut out voltage in order to protect the battery pack.
I have use a few on a number of diffrent projects, i don't want to pimp anything here but the details are found at HomePage of the Brain - Ebike Amp-hour and Watt Meter

 

[coops]

Hi Aero

Thanks for the link; can that be used to limit the top speed, for instance e.g. to 15mph, so that its impossible to exceed that? That would be useful .

I don't think its a big issue though unless you make a bike which greatly exceeds the limit, but it has other uses if it can accurately monitor your energy use & remaining battery charge: the simple "battery meters" on some bikes are a notoriously poor "fuel gauge".

Stuart.

 

[Aero]

Yes the new model will limit top speed, the controller/data logger takes control of the hall throttle output, speed is measured by either wheel sensor or motor hall sensor, max current and min battery voltage can also be programmed as well, I have not used the new model yet but the old model was just great.