Bosch CX pedal resistance

[Jon Matthews]

Hello,

I just got a bike stand today to do some routine maintenance. I was amazed how much power it took me to drive the pedals round by hand with the motor switched off. I have ridden it switched off and it feels like hard work. Is this normal?

Thanks in advance

 

[soundwave]

yes as it is the way the bosch motor is geared

 

[Jon Matthews]

yes as it is the way the bosch motor is geared

Thank you for the reply, I guessed as much but my lack of experiemce didnt give me the answer. Still loving my bike, the assistance is going down and the miles are going up.

 

[BigG]

I had the same problem with my last two bikes with the Bosch system. I loved the power but one day I rode out of the village (downhill) and when I got onto a flat piece of road I thought I had the brakes on..... please don’t laugh... I’d forgotten the battery! However Bosch have introduced a new system which they claim is much easier to pedal if you run out of power, or forget to put the battery on when you set off!

 

[Fat Rat]

To be honest I don’t really notice it cycling I guess it depends what your fitness levels are
Obviously I have noticed it on the stand with the motor off but on the move past the cut off speed no
Then my other non assist bike is a 4” tyre fat bike so there’s a little drag there too

 

[Jon Matthews]

I can’t say I really notice it when riding, I was just amazed how much resistance I felt on the stand. However I don’t think I had the system powered up. I’ll give it a try with the power on with zero assist when I get home at the weekend.

 

[Fat Rat]

I’ll give it a try with the power on with zero assist when I get home at the weekend.

It will be the same
The drag is mechanical not electrical
It’s the gears inside the motor

 

[Gringo]

However Bosch have introduced a new system which they claim is much easier to pedal if you run out of power, or forget to put the battery on when you set off

Yes that'll be the 3 gen motor, the active line range

 

[georgehenry]

My Yamaha 2015 PW can be ridden with the motor off with apparently almost no obvious resistance although any ebike without assistance is still a heavy bike so best cycled with the motor off on level or only slightly uphill gradients rather than anything too uphill where the weight quickly makes itself felt.

 

[Andy Tashkent]

I recently procured a cube reaction hybrid pro race 500 with bosch cx motor. I noticed today that if i try to pedal with the system on, but assist off, there is alot of resistence, very hard to pedal. Almost impossible. If I turn the whileole system off however, the resistence releases. Can this be normal? I live in Uzbekistan- no mechanic to check it. Can this be because of cold weather, now only plus 2 celcius.

There is also a little noise in the motor i think when pedaling with higher gear. Like a loose ring or something.

Should i be worried, or happy?

Thanks for reading and any tips!

 

[Nev]

Hi Andy, I have a bosch CX motor on my Cube e-bike and I don't notice any difference if I have the system switched on but no assistance selected or if I have the system switched off completely. It is the same in both situations. I don't think temperature has much to do with it either. It has recently been around zero degrees celcius here and its still exactly as I describe above. I wonder if you might have some kind of fault on your system which when powered up is creating the extra drag.

 

[Nealh]

I recently procured a cube reaction hybrid pro race 500 with bosch cx motor. I noticed today that if i try to pedal with the system on, but assist off, there is alot of resistence, very hard to pedal. Almost impossible. If I turn the whileole system off however, the resistence releases. Can this be normal? I live in Uzbekistan- no mechanic to check it. Can this be because of cold weather, now only plus 2 celcius.

There is also a little noise in the motor i think when pedaling with higher gear. Like a loose ring or something.

Should i be worried, or happy?

Thanks for reading and any tips!

I have no experience of Bosch/Yam mid drives etc,etc but what you describe and if it was a hub drive I would say it was a phase wire or controller mosfet issue.

The fact no resistence is present when system is off may also back up the issue.
Is it possible to disconect the conntroller wiring on these drives, if so then see how the drive turns. If all is ok and then you reconnect wiring and issue retrns then the fault is likely a controller issue.

 

[Andy Tashkent]

Thank you both. It seems to come and go, more so after having gone uphilI for 1-2 km and reaching even.ground again. I also notice, especially after riding home from.work good parts uphill using the sports assist level, that when you pedal the bike slows down - feels like you apply the brakes a little - from its rolling speed if you are in low gear. It feels thus like a motorcycle or car: you lift the clutch and the engine adapts the speed as per motor. In traditional bicycles this would of course not happen. Perhaps this is normal? Or the control unit is faulty.

 

[Nev]

Perhaps this is normal? Or the control unit is faulty.

This doesn't sound normal. Do you know someone local to you that has a pedelec with the Bosch CX motor? If so ask them to take your bike for a test ride and see what they have to say. If you don't know anyone then you will probably have to take it to a bike shop and ask them to test the bike for you.

 

[Andy Tashkent]

Thanks Nev. They are very rare here. Only seen mine so far , and the dealer's mechanic is having these in front of him the first time. I have warranty from the dealership here, but a bit hesitant to let the shop open the motor, as not so sure whether they will know what to do. I suppose I could try to get a shop in Europe to help under the warranty (though they are of course not obliged to as per Cube policy) when back.

I was considering biking from here to Europe next summer, but am beginning to think that these things may not be reliable enough to do so - better done with a trad. bike! This is a new bike after all. And good heavens what will happen when it rains!! Have to make sure this thing works any how before attempting.

I have a feeling the behaviour is connected to something being loose in the motor as there is a slight grinding sound in upper gears coming from the motor direction. I saw some other threads on this. Maybe something being lose will make the bike behave as it does at times!

I just might try with the local mechanic and see what he says and keep you posted.

 

[MikeS]

I have occasionally noticed the exact same effect on my Active Line Plus motor. I am particularly sensitive to this 'resistance' issue because I had a tremendous problem on my Carrera Crossfire bike (not a Bosch motor). On the Crossfuse (Active Line Plus) it is only a very occasional problem and only slight and disappears quickly - it's as if some sticky grease prevents the freewheel from operating properly if that's even possible.
Mike

 

[Fat Rat]

I was just about to suggest a rear hub freewheel issue
So as above is your freewheel ok as there no other way you would feel resistance not peddling

 

[Jon Matthews]

I had my bike of the floor in my maintenance stand this week nd to change the rear tyre for something more grippy off road. I ended up removing the chain which is fairly new and gave it a good clean and lube. With the chain off there is zero resistance when pedaling with the motor off or on. I reconnected the chain and found a bit more resistance, but put this down to transmission loss. Maybe Ive just run in all the parts after 700 miles. It's not an issue anymore and I wonder if I was mistaken in the first instance.