Faulty eCarrera Crossfire

Andy McNish

Pedelecer
Nov 28, 2018
232
123
As they say in Game of Thrones 'It is known' :)

To summarise the overall advice for new budget ebikers in this forum:

1. Do NOT buy a Crossfire from Halfords.
2. If you want a reliable hub motor bike look at getting a conversion kit or bike from someone like Woosh.
3. The best value crank drive is Halfords Crossfuse because if you wait for a sale you can stack discounts and get a Bosch ALP (one of the best overall systems out there) for less than £1300.
4. If you can stretch up into the £1500-£1600 range then there are often deals available on new crank drive bikes of better build quality/components than the Crossfuse - such as Cubes and sometimes even Haibikes. These are basically bombproof bikes built by Germans and their only downside is their weight. I have a £1570 Cube with a 500W battery - Bosch ALP - and have done 1400km on it since Xmas, mainly off road, with literally not even a squeak.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
1,798
408
Basildon
As they say in Game of Thrones 'It is known' :)

To summarise the overall advice for new budget ebikers in this forum:

1. Do NOT buy a Crossfire from Halfords.
2. If you want a reliable hub motor bike look at getting a conversion kit or bike from someone like Woosh.
3. The best value crank drive is Halfords Crossfuse because if you wait for a sale you can stack discounts and get a Bosch ALP (one of the best overall systems out there) for less than £1300.
4. If you can stretch up into the £1500-£1600 range then there are often deals available on new crank drive bikes of better build quality/components than the Crossfuse - such as Cubes and sometimes even Haibikes. These are basically bombproof bikes built by Germans and their only downside is their weight. I have a £1570 Cube with a 500W battery - Bosch ALP - and have done 1400km on it since Xmas, mainly off road, with literally not even a squeak.
That's pretty good advice. the only thing I would add is that a lot of people prefer the cadence-based control systems that you get on Chinese type bikes, and they prefer the ride you get with a hub motor, so there's still a strong case for bikes in the £1200 to £1500 price bracket from Juicy, Wisper, Oxygen, Woosh, Volt and similar.

All those companies can give you exceptional service much more than what they're obliged to under the warranty.
 

Andy McNish

Pedelecer
Nov 28, 2018
232
123
That's pretty good advice. the only thing I would add is that a lot of people prefer the cadence-based control systems that you get on Chinese type bikes, and they prefer the ride you get with a hub motor, so there's still a strong case for bikes in the £1200 to £1500 price bracket from Juicy, Wisper, Oxygen, Woosh, Volt and similar.

All those companies can give you exceptional service much more than what they're obliged to under the warranty.
Yes. I should have made it clear that other reliable UK based hub system manufacturers are available and that 3 and 4 only apply if you want a crank drive!

And that especially if you have health issues and can't reliably supply much power of your own, cadence may well be preferable to a torque sensing crank based system, in which case the reliable UK manufacturers will happily fill the gap (as the Crossfuse and German bikes mentioned are all torque based).

And of course, most importantly, test different options first to see what suits.
 

NewtSoup

Pedelecer
Jan 18, 2018
30
15
47
Leicester UK
If the Carrera Crossfire hadn't had the problems with the cut-outs, which of the two bikes do you prefer?
Crossfuse hands down. it's superior in every way. The mid drive runs through the gears resulting in a more efficient use of battery power.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
1,798
408
Basildon
The mid drive runs through the gears resulting in a more efficient use of battery power.
This come up from time to time, but it's actually a fallacy. Several tests have been done, and the results indicate that there's not a lot in it, but if anything, hub-motors are more efficient. Like everything, the external conditions have much more effect than the technology and processes within the system, so it's difficult to draw any real conclusions.

Whether the motor goes through gears or not, has little bearing on efficiency. A hub- motor gets its best efficiency at a certain wheel-speed, while as a crank motor gets it at a certain cadence. Neither of those two parameters are constant during riding. What's important is the speed at which the motor rotates. Both crank-motors and hub-motors use their complete range of speeds.

All things considered, a hub-motor will always be more efficient at its ideal speed because there are less drive train losses.
 

ebiker99

Pedelecer
Feb 17, 2019
201
63
This come up from time to time, but it's actually a fallacy. Several tests have been done, and the results indicate that there's not a lot in it, but if anything, hub-motors are more efficient. Like everything, the external conditions have much more effect than the technology and processes within the system, so it's difficult to draw any real conclusions.

Whether the motor goes through gears or not, has little bearing on efficiency. A hub- motor gets its best efficiency at a certain wheel-speed, while as a crank motor gets it at a certain cadence. Neither of those two parameters are constant during riding. What's important is the speed at which the motor rotates. Both crank-motors and hub-motors use their complete range of speeds.

All things considered, a hub-motor will always be more efficient at its ideal speed because there are less drive train losses.
I wonder if this is also true in hilly terrain with a lot of climbing. When climbing steep hills hub motors would be running a low rpm (since speed will be low) while crank motors should be running a normal rpm if the correct gear has been selected and you haven't run out of gears.

Any thoughts?
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
350
128
All things considered, a hub-motor will always be more efficient at its ideal speed
That is true, except it doesn't consider the important fact that a hub motor spends a lot of time (especially on hills when you need the efficiency most) way below its ideal speed, just as ebiker99 suggests.

It the motor is powerful enough to keep to (say) 8 mph on your steepest hills, or if you are willing to put in the extra effort needed to keep to that speed, then the efficiency will be good. But once you drop to a lower speed on most hub motors, efficiency drops quite quickly. see https://www.ebikes.ca/tools/simulator.html for your favourite motor.

It would be possible to gear hub motors lower; they would then be limited at the top of the speed range.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
1,798
408
Basildon
I wonder if this is also true in hilly terrain with a lot of climbing. When climbing steep hills hub motors would be running a low rpm (since speed will be low) while crank motors should be running a normal rpm if the correct gear has been selected and you haven't run out of gears.

Any thoughts?
That's a good question. The only documented test was done by a German bike magazine, where they tested a bunch of Ebikes by seeing how far they'd run up a steep mountain. I can't remember all the bikes involved, but there was a mk1 Bosch, Kalkhoff crank drive, KTM hub-drive and Bionx hub-drive. The KTM won by a country mile. It had by far the best efficiency, was fastest and went the furthest. The Bionx was second. It looked like the riders were all fairly fit. Maybe less fit people would get different results.

All motors lose efficiency when they slow down, but they give highest torque at low speed. If you can keep your cadence high enough on a crank-motor, you should get good efficiency. That's not so easy on some hub-motors, especially low powered ones, however, hub-motors with a low maximum speed can have good efficiency.

Basically, there are too many factors that affect efficiency to make any clear rules, except that you can say that if your bike's motor characteristics matches your personal and ride characteristics, you get good efficiency, and if it doesn't you won't.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
1,798
408
Basildon
All things considered, a hub-motor will always be more efficient at its ideal speed
That is true, except it doesn't consider the important fact that a hub motor spends a lot of time (especially on hills when you need the efficiency most) way below its ideal speed, just as ebiker99 suggests.

It the motor is powerful enough to keep to (say) 8 mph on your steepest hills, or if you are willing to put in the extra effort needed to keep to that speed, then the efficiency will be good. But once you drop to a lower speed on most hub motors, efficiency drops quite quickly. see https://www.ebikes.ca/tools/simulator.html for your favourite motor.

It would be possible to gear hub motors lower; they would then be limited at the top of the speed range.
Crank motors have the advantage that they can produce good power over a large range of speeds because of the gears. Efficiency is much more complicated because of the number of variables that contribute to it.
 

Darren Hayward

Finding my (electric) wheels
Mar 25, 2015
17
2
56
From my recent experience it is riding style that has the biggest effect on efficiency.

Oh yeah, waffle warning...

I'm 56, overweight with dodgy knees. I've owned a UCR 30 for 5 years. It's a cadence front wheel hub with 400wh battery. I fell into a riding style where I would pedal until I reached around 16 mph and then I would just turn the pedals over and let the motor carry me along , only pushing on the pedals again if the bike slowed and the cadence/speed equaled out. This is a very lazy riding style but it suited me well. According to the manual there are 3 power settings but I put it in 3 when I first rode it and it's still there now.
I used the bike for commuting and shopping but in the heatwave last year I started doing some leisure riding. And here the problems started. When new the bike had a range of 20 miles. Now it was around 14, which seemed to get me only halfway to everywhere I wanted to go. I tried to buy a second battery but EBCO had battery supply problems. I decided to buy a new bike.
Enter a Cube Hybrid Touring pro 500. I HATED it.
I had to pedal much harder than I wanted too. It's a Bosch ALP so it should be easier. What was wrong?
On the third day I used it to commute. What a revelation. Going uphill it is a good 50% faster than the UCR30.
But on the flat it was still rubbish. Then I worked it out. With an ALP I needed to ride differently. I relaxed and ignored the display, simply pushing as hard on the pedals as I wanted too (IE not that hard) and letting the power boost/speed sort itself out. With this simple change it was a joy to ride. I LOVED it.
My first long ride was along the Bristol to Bath railway path. A total of 29 miles, in Turbo. Well I didn't buy an Ebike to pedal it myself. I was a bit concerned about the batteries range but I just winged it. 29 miles later, turbo all the way, I had only just dropped from 4 bars to 3 bars about 3 miles from home. The display was claiming a remaining range of 17 miles. And I've done similar rides with similar ranges since. That is pretty incredible range given that it's all in turbo. Which brings us back to riding style. What is happening is that I'm pushing on the pedals and riding at just over 16 mph with just a little bit of boost on the flat. Then the boost comes in and I fly up the hills, then coast down the other side of the hill. This is a very efficient way to ride. Average speed is usually just under 15 mph with minimal effort.
I can now see just how inefficient the way I rode the UCR was but also how inefficient cadence setups can be.
With the ALP motor the way the power fades in and out is flawlessly smooth and the way I ride it, it has massive range. I don't think you are ever going to get much more efficient than that.



Darren
(waffle over)
 
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MikeS

Pedelecer
Jun 29, 2018
226
54
69
What I have discovered about the Bosch ALP is that the power is indeed very dependent on the cadence (even though it's a torque sensing motor). On very steep hills I was grinding to a halt even though I was in bottom gear and in turbo mode. But if I rode in moderate S-shapes across the hill the power generated by the extra speed of pedalling that it allowed me now lets me get up the steepest hills without walking. Going to try it on the Chimney at Rosedale Abbey at which I failed miserably with a straight up approach.
Mike