Flit 16

[Freddy Kruger]

Hi,

One moment, please...

I like the look of this folding bike but find it unusual that it uses a 220w motor as opposed to the 250w that seems more common.
They claimed it gives them much better acceleration and allows the use of maximum torque.
I'm struggling to understand and they are now being evasive in their answers.
Can anyone expand of the reason?
That aside I really like the look of it and fancy the ability to throw 2 of these into the car boot for trips off.
J

 

[flecc]

I like the look of this folding bike but find it unusual that it uses a 220w motor as opposed to the 250w that seems more common.

Both figures are meaningless with regard to actual power, all e-bike motors deliver far more.

The EN15194 technical standard requires a motor can deliver 250 watts continuous without continuously heating to failure point. It's likely this motor can only deliver continuously to 220 watts without starting to heat up too much, so doesn't quite meet the standard.

In practical use on the road it won't make any difference since an e-bike is never continuously at full power and it's the controller that dictates the actual power level delivered. We've had a number in the past that were only 180 or 200 watts rated. For your casual use I'd say go ahead if everything else about the bike is ok, especially since small wheels place less demands on the motor due to mechanical advantage.

This is a complicated subject, which is why they are being cagey.
.

 

[Gavin]

That's quite visually appealling and with a couple of interesting engineering details, however that's a lot of money for a single-speed folding bike.

Your money could go a lot further in such a competitive market sector with so many models to choose from....

P.S. Welcome Freddy!

 

[vfr400]

The motor has very little to do with how much power you get. The power is decided by how much current the controller gives it and the battery voltage. In simple terms, power = volts x amps. The motor is only a transducer. It converts that electrical power into motive power and waste some as heat. If you put a 200w or 500w motor in that bike, you'd experience the same power.

As said above, the watts written on the motor have very little significance. They're mainly stamped like that for legal compliance, depending on which countries they're sold in.

 

[Dave@FLIT]

Hi all,

Dave here from FLIT. Glad to hear you like the bike Freddy and sorry for any confusion!

We used this particular motor for a few reasons;
- it's made by Bafang who have a good reputation and good spare parts availability
- it was (and I believe still is) Bafang's lightest rear hub motor
- it has an unusually narrow OLD (120mm instead of the common 135mm) which helps when designing for a compact fold
- it has a 9T casette driver (like the type you'd find on a BMX) instead of the more common 13T freewheel which means we don't need such a large chain wheel to get a decent number of gear inches (less weight & better for fold design)

As other posters have mentioned, the 220W rating is the continuous power, not the peak power. The peak power is limited by the controller. In our case, the controller max current to 13A, so power peaks at 13*36= 468W.

So does this mean that a 250W Bafang motor will have better hill-climbing ability than our 220W motor? Yes and no. On a bench test, the 250W motor will almost certainly have higher torque but in real world riding other factors come into play.

Most of the weight of bike plus rider is acting over the rear wheel and this further increases on inclines - the steeper the incline, the less weight on the front wheel. To account for situations where the rider is on a steep incline with little traction (wet road + slick tires), we would have to be careful about how much current we send to a front wheel motor. With the motor on the rear wheel we don't have this limitation - the steeper the hill, the more weight on the rear wheel - so we can drive a rear hub motor and max controller current (i.e. max torque) without worrying about wheel slip.

I've probably rambled on enough already, but it was actually myself nearly flying off a front hub ebike whilst going over a steep bridge during early testing that convinced me we needed to design around a rear hub motor!

In conclusion, yes it's a small motor, but we don't restrict it so it performs surprisingly well on steep climbs. Probably the steepest I've tried personally was Constitution Hill in Bristol;

Freddy, if you're anywhere near Cambridge or London please let us know - I'd love for you to test ride the bike and answer any questions you have in person.

Thanks for your interest,
Dave
FLIT Co-founder

 

[Woosh]

The motor has very little to do with how much power you get. The power is decided by how much current the controller gives it and the battery voltage. In simple terms, power = volts x amps. The motor is only a transducer. It converts that electrical power into motive power and waste some as heat. If you put a 200w or 500w motor in that bike, you'd experience the same power.

I used to build large PA speakers back in the 70s and burned a few coils after feeding too much power into them. Back then, I just rebuilt the coils but I can't see anyone redoing the coils of a motor.

 

[guerney]

@Dave@FLIT - I'm curious as to how well your chameleon tongue mudguards work in practice, do you find they bounce up and down noisily on the rear tyre, causing them to coil? Does the front mudguard waggle side to side and up and down, bumping into legs or clothing?

https://flit.bike/engineering-stories-redesigning-the-rear-mudguard/

 

[saneagle]

I used to build large PA speakers back in the 70s and burned a few coils after feeding too much power into them. Back then, I just rebuilt the coils but I can't see anyone redoing the coils of a motor.

If burning motors was a problem, we'd see them on this forum, but we don't, so it's not a problem. You shoould know that. Why are you trying to scare people? Even the ones I have seen maybe ten years ago were due to connection issues or mosfet failure, not because of power.

 

[Woosh]

If burning motors was a problem, we'd see them on this forum, but we don't, so it's not a problem. You shoould know that. Why are you trying to scare people? Even the ones I have seen maybe ten years ago were due to connection issues or mosfet failure, not because of power.

It was elinx and blacklite who attracted me to the problem of demagnetisation. We don't pay attention to issues of temperatures higher than 75C when permanent magnets started to lose their magnetism. That reminded me of the time when 200W+ loudspeakers like those from JBL cost a small fortune. Reapiring was then a good option. Back then, I imported Celestion and Goodman speakers and Quad amplifiers from UK (to France).