bigger or smaller?

[lordvincent]

I want to change the wheel size in the impulse system in order to get a couple of extra mph assist - just to 20mph or so (where I run out of gears).

If the actual wheel size is 28", what should I dupe the system into believing the wheel size is?

I thought it should be a smaller size but have confused myself and no longer have a clue..

 

[soundwave]

not used 1 but imo you will get 1mph if that b4 you get a error message.

 

[lordvincent]

For impulse, a dongle is not necessary since changing the wheel size will mean that the system thinks you are going slower than you are.

 

[D8ve]

Smaller wheel size same rpm is slower.

 

[soundwave]

i bet it will not work otherwise no point in making a dongle for impulse motors.

could try the magnet on the peddle trick?

 

[soundwave]

 

[lordvincent]

The problem is that the wheel size change has to be done with a Derby Cycle service unit which only dealers have access to. The bike is out of warranty so I don't see why they would not do this "at my own risk".

 

[soundwave]

forget it you will have no chance getting them to do that for you even if you pay.

i doubt it would work anyway tbh wheel size is 1 thing the 15 mph limit is the other.

 

[soundwave]

put it this way if a shop did do that and you hit someone they would be liable for it.

 

[soundwave]

if you want you can have a 3.2 dongle but will have to get that as a custom order.

that will be 75kph cut off

 

[lordvincent]

@soundwave, yes I suppose this might be academic interest only. I'm not too bothered about it really, but I would like the bike to assist throughout the available gears, at at the moment it cuts off in top gear when a decent cadence is reached, which is a bit annoying.

@D8ve, thanks, that cured my brain malfunction. So I reckon it would need to be set to about 22 inches to increase the cutoff to about 20mph, unless I'm still confused..

 

[soundwave]

i can change my wheel size in the hmi but it makes no difference to the top speed and will cut out at 15.5mph give or take a bit.

think i got a extra 1mph last time i tried and gave up and got a dongle and trust i did not want to spend 100 quid on it but had no other option.

only bosch can change the speed setting on my bikes motor so that will never happen and no dealer has that software anyway so might be the same with the impulse motor?

if my bike went 15.5 mph id never had bought it as it would do my head in as its just too slow for me anyway.

 

[Tomtomato]

i doubt it would work anyway tbh wheel size is 1 thing the 15 mph limit is the other.

How do you think the speed is calculated by the bike then? GPS?

 

[soundwave]

by the software installed via the sensor wheel size and speed

 

[Tomtomato]

by the software installed via the sensor wheel size and speed

Not sure what this means, but no, speed on those bikes is calculated by counting the number of wheel revolutions (via the wheel sensor) over a specific time interval, multiplied by the wheel size. So yes, changing the wheel size will impact the speed calculated by the bike, and therefore if the bike "thinks" it's going slower than its actual speed, would allow for higher speed cutoff.

 

[anotherkiwi]

Small wheels spin faster than big wheels to cover the same distance. And it is some ungodly hour of the morning! I'm at work, what are your excuses?