How to remove speed limit on Momentum Upstart?

[MomentumUpstart]

Hi, I have a Momentum Upstart electric bike. My average speed is around 16mph which is where it feels like it is still assisting. How do I remove the speed limit for cycling around on my parents property?

I have searched but cannot find a thread on how to do this for this type of bike. Any help much appreciated!!

 

[MomentumUpstart]

I believe it has the following motor:
Bafang/8FUN SWXK 36V250W motor (front hub)

 

[trex]

I don't think the Upstart is restricted. It'll go as fast as you can pedal.

 

[MomentumUpstart]

It really feels like the power quickly tapers off above 15mph. I agree its not like a fixed speed setting like other bikes that owners complain of pulsing on and off. Around 15mph it sits there very nicely without much effort, but increase it to 20mph and its very difficult to hold it there for decent stretches. It feels like no assistance at 20mph.

On the front hub it has a sticker saying 250W and 25km/h. I am in Australia and they are very strict with regulations.

 

[trex]

speed limiter is only needed on bikes with big and powerful motors, usually fitted with an LCD for speed readout.The Upstart has a lightweight 250W front 8-Fun SWXU motor and no speed display.

 

[MomentumUpstart]

Ah I see. I just saw member "surfer6900" who has a Momentum Upstart with an aftermarket controller and removed the torque sensing bottom bracket.

I wonder if the power is limited via the torque sensor? So 250W motors cant maintain 20mph on the flat without considerable effort?

 

[trex]

yes, that's a straightforward way of increasing the speed. If you've good experience of e-bike electronics, it's a 30 minute job. Replace the torque sensor with a thumb throttle for effortless riding.

 

[Deleted member 4366]

I don't believe that Trex is correct. In order to get any hub-motor to run at 15mph, it needs to be able to spin to at least 20 mph because of two reasons: firstly, if it could only do 15 mph with a charged battery, it would be down to a maximum of 11 mph when the battery is run down. Secondly, if the motor ran to a maximum speed of 15 mph, it wouldn't have enough power to go past about 13 mph on the road. Maximum power comes at about 2/3 maximum RPM. After that, power ramps down to zero at maximum rpm.

It's easy to see if your bike is restricted. For an unrestricted hub-motor, the maximum speed is directly proportional to the battery voltage. Charge up the battery to maximum (42v) and check the wheel speed with the wheel off the ground, then go for a ride to run the battery down to say 36v and check the wheel speed again. If there's a significant difference in speed (14% in this example), then the motor isn't restricted.

I haven't studied the Momentum control system, but I would guess that it's a standard controller that can be replaced if you can't adjust the speed through the LCD or other means. There's a fair chance that it's limited by software.

 

[trex]

that depends on which year. The newest Upstart has much more sophisticated elecronics and 250W motor.
But because the bike has torque sensor and LED panel display, you can't check out noload speed, only go by what the OP has reported.
If the OP wants to look for an after market controller, he should post pictures of the existing controller here for advice.

 

[Deleted member 4366]

A bit awkward, but get a friend to hold the bike up while you apply the back brake and push the pedal diwn to operate the motor. See how fast ut goes.

Which version is it? The main obvious difference is the motor.

 

[trex]

that method does not work, the Upstart does not have a speedo.

 

[MomentumUpstart]

I just bought it so Im guessing its the latest model, although it definitely says 250W not 180W. Yes no speedo and no lcd at all, just has a very basic LED panel.

Has a torque sensing bottom bracket and a SRAM automatic 2 speed hub.

Looking at my stats my average speed seems to stay about the same throughout my 20 mile each way to and from work. My speed seems to sit at around 16mph on the flat.

 

[MomentumUpstart]

So you want me to pull out the controller and have a look? There is a sticker on there "warranty is void if removed" but I can try being very gentle with it.

 

[trex]

you don't get much more in speed replacing the controller because the motor is limited by its noload RPM but a more powerful controller will help will hill climbing. A 700C wheel with low power motor will give about 20mph max. BTW, all e-bikes are supposed to have a 250W motor, the 180W is more techie's talk, relative to the 250W 8-Fun SWX.

edit:
I was wrong. the motor is 250W

 

[MomentumUpstart]

Ok so no restriction on the bike, its running pretty much as good as it can. If I want more speed I would need to start again with a new motor etc.

Thanks guys

 

[Deleted member 4366]

you don't get much more in speed replacing the controller because the motor is limited by its noload RPM but a more powerful controller will help will hill climbing. A 700C wheel with low power motor will give about 20mph max. BTW, all e-bikes are supposed to have a 250W motor, the 180W is more techie's talk, relative to the 250W 8-Fun SWX.

Trex, how do you know what the no-load rpm is?

 

[trex]

I don't know the noload RPM. I guess his motor is 8-Fun SWXK 201 RPM, noload RPM about 220. That's why I said you've got to go by what the OP reported, he's got to about 16mph. With a more powerful controller, he probably can push up to 18mph on his 700C wheels, but it'll help on hills.

 

[Deleted member 4366]

You can get the the QSWXK in any speed. 220 rpm in a 28" wheel with a fully charged 36v battery is 20.6 mph anyway. He's getting 16mph because his speed is limited otherwise his speed would be down to 12mph when his battery is run down.

 

[trex]

that may be the case but he can't do much to his present controller. The only way to find out if his controller is restricted is to plug in a new after market controller and a throttle. If he does that without speed increase then he would have wasted his money.

edit:
I was wrong. the motor is 250W

 

[Deleted member 4366]

180w doesn't mean anything. Look at the 200w Heinzmann with 36v and 28 amps.