Greater than the sum of its parts .

[neptune]

OK , so I have been riding an ebike now for 5 weeks . I have been having some thoughts about the relationship between motor power and pedal power . Mostly my ebike journeys are 5 miles or less . I tend to use the bike in throttle mode , using the pedals up to about 5mph , and then opening the throttle . So I cruise along at a nominal 15 MPH . Suppose I wanted to make a journey that was longer than is possible on motor power alone . In that case , I have to ride on part throttle at say 11 MPH , whilst pedalling lightly . If I go much faster , and am in my highest gear , I need to pedal faster than is comfortable for long trips . The big question is this . If I was to raise the gear ratio by fitting a larger chainwheel , or smaller sprocket , would I gain anything , or , as I approached 15 MPH , would the motor start shutting down , leaving me to do all the work ? The bike is a Powabyke Euro with 5 speed gears .

 

[flecc]

The motor would still leave you to do all the work over 15 mph, though you wouldn't have to pedal as fast as before.

 

[morphix]

OK , so I have been riding an ebike now for 5 weeks . I have been having some thoughts about the relationship between motor power and pedal power . Mostly my ebike journeys are 5 miles or less . I tend to use the bike in throttle mode , using the pedals up to about 5mph , and then opening the throttle . So I cruise along at a nominal 15 MPH . Suppose I wanted to make a journey that was longer than is possible on motor power alone . In that case , I have to ride on part throttle at say 11 MPH , whilst pedalling lightly . If I go much faster , and am in my highest gear , I need to pedal faster than is comfortable for long trips . The big question is this . If I was to raise the gear ratio by fitting a larger chainwheel , or smaller sprocket , would I gain anything , or , as I approached 15 MPH , would the motor start shutting down , leaving me to do all the work ? The bike is a Powabyke Euro with 5 speed gears .

I found on my bike (a self-build) that having it as highly geared as possible works best for me to get maximum speed with the least effort.. in fact when my throttle is fully open I can't keep up with the motor unless I am highly geared, then I just seem to cruise pedaling lightly and I can even get above 18mph.. my bike was originally 21-speed but I took the left-side shift off and left the chain on the smallest sprocket and on largest chainwheel. I only have two changeable gears now, 5 and 6! Riding unpowered in those gears is not an option so this really is an electric bike only now, but it's a small sacrifice I think.

 

[Deleted member 4366]

Changing the gearing won't affect the motor in any way, but, if you can't pedal fast enough, then it'll make you more efficient to raise the gearing with a bigger chain-wheel.

 

[neptune]

Excellent answers .I have only 5 gears , but I use only gears 3 , 4 , and 5 . As we have no hills , and I always use it on tarmac , I can peddle off from a start in 3 . So gears 1and 2 are not a lot of use to me . I have not counted the teeth on the chainwheel , but it looks smaller than your average chainwheel . So , ideally , I could do without gear one , and gain a new gear at the top end , if you see what I mean , or even eliminate gears 1 and 2 and gain two gears at the top end . I am assuming that the chainwheel is just a standard pushbike type . I guess I need to do some teeth counting to figure out what size chainwheel I need . I would think that changing the sprokets would be harder due to the limited available options .

 

[flecc]

Powabyke chainwheels were non-standard so yours may be too. A to B magazine solved the problem on one by bolting a larger chainring onto the existing chainwheel as here:

 

[neptune]

Thanks flecc . That`s my kind of solution . It is likely to be low cost using salvaged parts , and has the added advantage that you can return it to standard , or try different sizes . I will keep my eyes [sorry eye] open for parts .

 

[Deleted member 4366]

Does the Powabyke motor have a clutch? If not, what happens if you pedal more than 15mph? Does it get harder to pedal?

 

[neptune]

@d8veh . I am not sure if you would call it a clutch , it is more of a freewheel mechanism in the front hub . If you pedal fast enough you can exceed 15MPH , but the motor is still running ., but not helping .

 

[johnone]

You need a 48 tooth 5 bolt chainring,I bought mine off Ebay.(you will need to measure the distance between the bolts on your chainring)

 

[neptune]

@johnone . Thanks for that specific information , that is a big help . I was thinking about it on my ride this morning . Will I have to extend the chain , and how can I work out how much ?

 

[flecc]

Any 5 spoke 48 tooth chainring should do, since you'll need to centralise the chainring and drill the chainwheel on your bike to accept it. There's no existing holes to bolt it to. The chain will need to have an extra link for each 2 teeth increase.