Motor & Gears

[UrbanPuma]

Hi all,

When riding my powacycle puma, i find that the the gears are not able to keep up with the motor and as a result i find myself pedaling frantically without being able to increase speed.

Can anyone tell me if its possible to change the gearing so that i can keep up with the motor. I find that i have to use the throttle to get extra speed.

Here is a pic of the bike.Puma LPX Electric Folding Bike

Many thanks

UrbanPuma

 

[keithhazel]

you will get technical data soon from the people who know that stuff, i can give you first hand experience as i had a synergy folder,same problem as yours, i posted lots about it...i took to friendly cycle shop and got him to put a larger front chain wheel on and a set of small ones at the back, with a new chain as cogs where smaller,this increased the pedal speed in redelec mode by about 1.5 mph....but still only up to about 12.5mph... i had a 24 volt on my synergy same as you so suspect when you hit wind or gradient it will kill your speed to 10mph ish...effect...so plan B came into effect...I SOLD IT and bought a Quando...i dont need to pedal no matter how strong the wind or bad the gradient is,remind me again what peddeling feels like ????
good luck hope you solve what i couldnt..

 

[flecc]

As Keith says, it's very difficult to get high enough gears with 16" wheels. The most effective way is a much larger chainwheel, but that can make the fold size larger, get in the way of some models stands, and push the chain very close to the ground. Ride across a grass verge and you can find you've cut the grass and clogged up the rear mechanism. Equally, crossing a kerb or step leaves the chain dragging on the step due to it's low run.

On my 20" wheel Q bike, I have a huge 60 tooth chainwheel so have to be careful with the chain's low run, and yet the top gear is still only just high enough for me, so you can see the difficulty with 16" wheels.

Of course reducing the rear sprockets also helps, but the very small sizes like 9 tooth are very inefficient and wear at a very high rate.

It is possible with expensive solutions like the Rohloff 14 speed hub or SRAM's DualDrive, but these cost much more than your bike did.

So a larger wheeled bike is the best answer if the smallest size isn't essential for your travelling.
.

 

[UrbanPuma]

Thanks to both of you. It doesnt look as though i will gain much from changing the chainwheel...so guess if i needed to do some serious commuting etc i'd get a bigger wheeled bike as suggested. I'm quite happy with the bike for leisure purposes and it doesnt take up space at home.

Just thought i'd see if there was a solution

Thanks again

 

[Joe]

hi keith, if you do want to pedal as well as use the motor on your quando what speed can you reach without it becoming too frantic on the legs?

 

[flecc]

While waiting for Keith to come in with his answer, with my Quando before conversion I found up to 14 mph quite comfortable, with 15 mph starting to get a bit much all the time. It wasn't so much that the cadence was that fast, more the fact it seemed ridiculous at that low speed, so it felt awkward.

For short periods I could maintain just over 17 mph pedalling.
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[Footie]

Joe
" .... what speed can you reach without it becoming too frantic on the legs?"

No wish to hijack your thread UrbanPuma but I would be interested in the answer to this question too.

I know it's not really fare to compare a folding bike with a fixed frame but it's an interesting point. Especially if your comparing standard (unmodified) ebikes.

I have a 6 gear mountain electric bike (38kg - LSA) and mine is around 18 - 20mph - hardly formula one

My usual speed is around 15-17mph with regular help from the motor.
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[flecc]

To have any real meaning, the cadence (crank turns) for a bike should be known at the speed quoted.

On the standard Quando, the cadence at 14 mph is 69, at 15 mph 73, and at 17.5 mph is 85.

A sports cyclist's optimum efficiency is typically at a cadence of 90, so a Quando at 17.5 mph is getting very close to a competition cadence.

I recently touched a cadence of 113 at 27 mph on a downslope, and that seemed ok, but high cadences at low speeds makes one feel a bit ridiculous.
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[keithhazel]

While waiting for Keith to come in with his answer, with my Quando before conversion I found up to 14 mph quite comfortable, with 15 mph starting to get a bit much all the time. It wasn't so much that the cadence was that fast, more the fact it seemed ridiculous at that low speed, so it felt awkward.

For short periods I could maintain just over 17 mph pedalling.
.

my answer is a little less then you Flecc, you being i think you said 72 and me a sprightly 46 but im half a mile slower then you peddleing... ....however i know going down flyovers or steep hills im less then comfortable as the speed rises to 18 and above ....just so glad i dont live in hilly areas...