New ebike problems

[Bobbish]

6 weeks ago I bought a Cube Reaction Pro 500 with Bosch CX Performance motor. Out of that six weeks the bike shop has had it for the last 3 of them.
My problem is with power surges, when I am riding it I will get a small surge of power and the bike goes to 16 mph. This happened occasionally at first but when I decided to take it back it was doing it more frequent for instance 8 times in 300 yards.
After they run diagnostics on it they said the battery was short circuiting and they replaced the battery. I collected the bike on Wednesday rode it home and road it to work next day. They exact same thing happened while going uphill several times in a few yards. Phoned today and it doesn't look like they have done anything yet. Still waiting for the phone call back they said I would get on the update status.
While they have had the bike I have been using a Cube Reaction SL demo bike they gave me and it does not give me the same problem riding the same route which if was a normal thing I would think it would.

Does anybody have any ideas what it could be. I know you will get a power surge when you increase pressure on the pedals but its happening just cruising.

 

[Nev]

Is your speed sensor working correctly. Mine has been playing up (its getting replaced at the moment), but when it was playing up it was causing the motor to surge at times just as you describe. My bike is a Cube too with a CX motor.

 

[Bobbish]

Is your speed sensor working correctly. Mine has been playing up (its getting replaced at the moment), but when it was playing up it was causing the motor to surge at times just as you describe. My bike is a Cube too with a CX motor.

Thanks I will suggest that to them when I phone later

 

[GLJoe]

My problem is with power surges, when I am riding it I will get a small surge of power and the bike goes to 16 mph.
...
Does anybody have any ideas what it could be. I know you will get a power surge when you increase pressure on the pedals but its happening just cruising.

Sounds as if the torque sensor in the motor/drive unit assembly is malfunctioning.

Maybe you could use this to your advantage and sell it as is at an extortionate price? it seems to be the holy grail of many people on this forum to have a quality bike that propels you along without putting in any effort

 

[flecc]

it seems to be the holy grail of many people on this forum to have a quality bike that propels you along without putting in any effort

Do you have any data for that?
.

 

[Bobbish]

OK got my bike back yesterday, they have fitted a new speed sensor seemed OK coming home but I will find out on Monday when I go to work I have a 3 mile big hill to go up that is the main place I was getting the problem. Fingers crossed.
They said they have tried to get the problem to happen to them but it didn't so really they do not know if its fixed. If its not I don't know what to do I have had it 6 weeks and they have had it for 50% of that time and at £2200 its alot of money for a bike they have as much as me.

 

[Bobbish]

Sounds as if the torque sensor in the motor/drive unit assembly is malfunctioning.

Maybe I will suggest this to them if the problem continues

 

[Plodder Bob]

Sounds like a torque sensor issue rather than a speed sensor . I also have a reaction pro have noticed it very occasionally but usually only in EMTB mode where the bike decides which assist mode to use TOUR / TURBO . Possibly it’s a software glitch I’ve never noticed it in ECO or TOUR modes but it’s never caused enough of a problem for me to consider returning the bike . I would rather have too much assist than too little ! The wife has the Cube Access ( female version of the reaction ) she has never noticed any issue with hers but hers has only covered 320 miles mine is now over 1000 miles. Both of us are reluctant to use TURBO mode as I suspect it causes rapid wear to the chain and gears . Certainly care needs to be taken when shifting in turbo mode crank pressure needs to be eased when shifting. Hope you can get yours sorted they are great bikes my biggest issue is rear wheel punctures I’ve had 3 in the last fortnight

 

[GLJoe]

Do you have any data for that?
.

Just my observation at the moment. But then maybe that's not reliable data.

It would be fairly easy to do a trawl back through the posts here and come up with hard evidence though. However I'm in my inappropriate jeans at the moment, cooling off after some gardening. If I was to do anything cycling related, I'd be obliged to change into high performance clothing. Stretchy things that are comfortable, functional, and fit for purpose. Clothes designed for cycling related duties. Things with labels bearing names such as Altura, Endura, Bontrager etc. Anything else just isn't cricket .... er ... cycling.

 

[Bobbish]

Hi Just a quick update.
Had my bike back 2 weeks tomorrow everything seems to be working has it should no multiple power surges.
So everything crossed its fixed

 

[Nev]

I bought my Cube around the 4th of May so a couple of weeks after you I think. It sounds like fitting a new speed sensor has sorted out the problem. I had similar problem to you as I mentioned earlier in this thread, and a new speed sensor seems to have sorted out my problems too. I wonder if Cube bought a batch of faulty speed sensors, or perhaps its just a coincidence that bikes bought around the same time have had the same faulty component fitted.