Carrera Crossfire Excessive friction?

[David SK11]

Not sure if that is really the correct description or whether this is the right forum to post in, is there one more devoted to technical issues? Anyway here goes.

Rightly or wrongly I bought a Carrera Crossfire E second hand during lock down and was happy with it. If I had had a frame worth using I would maybe have converted a bike but I did not.

I was away for August and did not use the bike. Recently when I got on it again it seemed to require much more effort to pedal it on the flat without electric assist, more than I remember. It may well be that during the time I have not used it my leg strength has diminished (Probably unlikely since it was not good to start with, hence an E Bike).

When I spin the rear wheel by hand it does stop turning fairly quickly, indicating that there is some friction/resistance. With a rear hub drive eBike does the motor cause mechanical resistance when not powered and if it does is it significant? I am asking before I go on to check where the friction is originating and whether bearings etc. are set correctly.

Another thing is that when using e assistance I find the way it delivers power "Interesting" on the flat and minor hills I tootle along and all is well but when I go down the gears and increase the power assist level I feel like I am getting less assistance but I still get up hills I would not be able to get up without e assist ,

I am wondering whether it is
A) Just a feeling or B) something up with the cadence sensor or software.

Any comments?
Do manufacturers occasionally put out software updates?

Thanks in anticipation.
David

 

[Nealh]

A geared hub should quite happily freewheel as a non motor wheel does.

 

[vfr400]

No software updates that you can do yourself. I can't remember anybody else ever getting one on that bike.

I've ridden those bikes a few times. I always found them pretty normal and never had to think about pedal speed, though it's clear that you have to pedal with reasonable effort to get the maximum power.

The motor should only have friction when you spin it backwards. Only test with the brake caliper unscrewed and off the disc. If you get resistance in the forward direction with the brake off, either the clutch is stuck or the wheel hasn't been put on correctly. It's highly unlikely that anything is wrong with the bearings, though anything is possible.

There is a modification you can do to get power more easily if it turns out nothing is wrong.

 

[David SK11]

Thank you both for the replies. I will check how I was spinning the wheel, I think it was so the pedals were not moving so reverse I think. Brake calliper was still attached but pads were clear of disc, are you inferring there is a proximity effect? Air resistance in the gap?

With regard to resistance in the forward direction, is the clutch you refer to what I might call the ratchet mechanism on the rear sprocket or something else within the motor?

I am new to e bikes and have not ridden any other, because I bought it during lock down I was unable to do any sort of comparison testing.

 

[Nealh]

Geared hub motors have an internal clutch so when one rides with no power it will still happily freewheel. When/if trying to turn the wheel acw then yes you will feel some whirring resistance as the clutch doesn't freewheel, what you hear are the central planetary gears being turned by the casings teeth.
What counts is one lifts the wheel off the ground and turn it cw by use of the hand or pedals to see it freely rotates several if not a lot more rotations.

 

[David SK11]

Geared hub motors have an internal clutch so when one rides with no power it will still happily freewheel. When/if trying to turn the wheel acw then yes you will feel some whirring resistance as the clutch doesn't freewheel, what you hear are the central planetary gears being turned by the casings teeth.
What counts is one lifts the wheel off the ground and turn it cw by use of the hand or pedals to see it freely rotates several if not a lot more rotations.

Interesting, so is mine a geared hub?
Without thinking about it I kind of thought it was direct drive.

Does this mean that when I change the level of power assist the gears are being changed or is it that more power is being applied to the motor?

 

[vfr400]

You can't change the gears in the motor. The more power the controller gives the motor, the more torque you get.

 

[David SK11]

You can't change the gears in the motor. The more power the controller gives the motor, the more torque you get.

That's what I thought but it certainly sounds as though there are planetary gears within the motor assembly all be it with a fixed ratio.

Are there some hub or bottom bracket motors that are direct drive?

 

[Nealh]

As vfr mentions the gearing isn't changeable, the exception is the Xiongda 2 spd hub that does it automatically.
The gearing is a simplistic clutch with tri planetary gears running against a larger sungear machines on the main hub casing, the clutch simply allows freewheeling.
Unlike a D/D hub which has no clutch.

 

[Nealh]

D/D hubs are a plenty they are on ebay etc,etc and are heavier 5kg + hubs usually black and large in diameter, most are 1kw or more.

 

[David SK11]

D/D hubs are a plenty they are on ebay etc,etc and are heavier 5kg + hubs usually black and large in diameter, most are 1kw or more.

Thanks for the info.

 

[vfr400]

Are there some hub or bottom bracket motors that are direct drive?

No, they wouldn't get enough torque.