Bosch performance line cx - feels like it’s holding me back.

Mteam

E*POWAH Elite
Aug 3, 2020
1,765
1,703
gone
You're probably in too high a gear for the speed you want to travel at for your legs to easily turn without assistance from the motor.

I found that when I first got my ebike (with bosch gen4 motor) I would be in gears that felt fine when the motor was assisting, but as soon as the motor cut out when over the speed limit my legs werent strong enough to push the pedals fast enough so it felt like pedalling through treacle. but when you think about it, what do you really expect?

for example, Tour mode (not magic tour or whatever) adds 120% of whatever power you are outputting, eg if you output 100 watts, then tour mode is outputting 120watts on top of that, total watts = 220. 220 watts can easily turn a much bigger gear than 100 watts can, but as soon as you go over the speed limit, the motor cuts out leaving you to find another 120 watts - you're really going to feel that loss of power.

Solution - keep your cadence high (85+rpm) at all times, keep it in a lower gear than you+motor could ride in, dont be tempted to whack the bike into a big gear and pedal slowly. You can usually spot an ebiker from a mile away, their legs will be turning over at 40 rpm, but the bike travelling at speeds that would require 90rpm without a motor.
 

Waynemarlow

E*POWAH Master
Dec 6, 2019
1,039
861
Bucks
Umm I'm not sure there is not something on the Bosch Gen 4's that is restricting the overall speed. My friends Focus has been back to the dealer a couple of times with the same complaint. His definately does not disengage once over 16mph and feels like you are having to turn the motor over as well. When the battery is flat and switches off then it definately is almost get off and push rather than peddle.

Compared to my Fazua and Bafang which do almost totally disengage, its quite different. His dealer seemed convinced he could alter the disengagement of the motor somehow but out of frustration with having to take the bike back to the dealer, a Speedbox 4 happened to magically be fitted.
 

ashleydwsmith

Member
Apr 15, 2022
93
48
Guildford uk
Umm I'm not sure there is not something on the Bosch Gen 4's that is restricting the overall speed. My friends Focus has been back to the dealer a couple of times with the same complaint. His definately does not disengage once over 16mph and feels like you are having to turn the motor over as well. When the battery is flat and switches off then it definately is almost get off and push rather than peddle.

Compared to my Fazua and Bafang which do almost totally disengage, its quite different. His dealer seemed convinced he could alter the disengagement of the motor somehow but out of frustration with having to take the bike back to the dealer, a Speedbox 4 happened to magically be fitted.

interesting, I might have to try a different bike. It’s also bizarre how it doesn’t happen all the time. I.e today bombing down a hill, then happily pedalling along a flat at 18/19mph.
 

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
I've an update on this effect.

The other day im cycling home, going down a slight incline on a road, freewheeling at about 18mph without peddling. I start to pedal, the speed drops to maybe 17 or 16 1/2mph, i stop pedaling it increases again. I can physically feel the bike being held back.
 

emtbPhil

Well-known member
Jun 20, 2021
372
417
UK
That's inevitable - when you turn the pedals the motor is powered up - but not engaged because of the cut-off so you get the passive drag of the motor applied.

When you're not pedalling the only resistance you have is the freehub spinning away as the crank isn't moving.
 

ashleydwsmith

Member
Apr 15, 2022
93
48
Guildford uk
That's inevitable - when you turn the pedals the motor is powered up - but not engaged because of the cut-off so you get the passive drag of the motor applied.

When you're not pedalling the only resistance you have is the freehub spinning away as the crank isn't moving.

i guess the realisation I am coming to is that I’m not going to get to say 16mph and then my legs be able to push it through to say 20mph make sense?
it amazes me when you see these guys on YouTube doing trails on ebikes and comingout of a berm and pedalling as if it’s nothing
 

Swissrider

Well-known member
Nov 1, 2018
362
379
Switzerland
I think that all ebikes can feel like hitting a brick wall when hitting the limiter, but one can reduce the sensation. With my Brose on the flat I’ll change down to Trail or eco so the cut off is not so abrupt. In fact, on a slight downhill one hardly notices the cut off although counter intuitively one has to change up to compensate for the lack of assistance.

I also have a Bosch performance x motor which is on a town bike. Most of the time I’m going up or down quite steep hills and I use Turbo most of the time (because I’m in a hurry and range or getting fit are not issues) so it’s hard to hit the limiter uphill and downhill although there is some motor drag I don’t really notice it and can easily hit 50kph or faster. On the flat on either bike one learns to adjust one’s speed to just below the limit (which I increased slightly on both motors by changing the wheel circumference). I think working with the limiter is one of those ebike skills one learns over time and off-road 25 kph seems fine except for downhill where one can go as fast as you like.

In Switzerland one can buy ebikes which are limited to 45 kph instead of 25 kph but these bikes are classed as motorised vehicles so technically are not allowed off road, they have to be licensed and have a number plate and they are a lot more expensive although they have exactly the same motors and running gear. Nevertheless, they are quite popular, especially for commuting. If I really want to go fast I’ll take my motorbike!
 

emtbPhil

Well-known member
Jun 20, 2021
372
417
UK
i guess the realisation I am coming to is that I’m not going to get to say 16mph and then my legs be able to push it through to say 20mph make sense?
it amazes me when you see these guys on YouTube doing trails on ebikes and comingout of a berm and pedalling as if it’s nothing

Not unless you're downhill with a tail wind lol

You've got to remember as well it aint a light bike. It's like having a 15kg backpack on
 

Growmac

Well-known member
Subscriber
Dec 4, 2020
375
389
Wilts, UK
I've an update on this effect.

The other day im cycling home, going down a slight incline on a road, freewheeling at about 18mph without peddling. I start to pedal, the speed drops to maybe 17 or 16 1/2mph, i stop pedaling it increases again. I can physically feel the bike being held back.
That's not physically possible unless your freehub has seized. You can't put braking torque through the drive chain. If you tried the mech would get ripped off. You're mistaken.
 

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
That's not physically possible unless your freehub has seized. You can't put braking torque through the drive chain. If you tried the mech would get ripped off. You're mistaken.
Well thats the effect i found. Freehub is fine, bikes running fine, and thats certainly what feels like. I'll try it again, see how it goes. But as from the replies on this thread, something is amiss, and not all can be explained away as a freehub issue.

If it was a feehub issue, freewheeling alone would present an issue which would be noticeable. But beyond about 16mph, there is a discernible effect at play that appears to be drag of some sort.
It was such an odd sensation at the time made me take notice. But i only freewheels for a shortish distance(say 300m) so slowed down, pedaled etc so kind of dismissed it.
.
 

Mteam

E*POWAH Elite
Aug 3, 2020
1,765
1,703
gone
Well thats the effect i found. Freehub is fine, bikes running fine, and thats certainly what feels like. I'll try it again, see how it goes. But as from the replies on this thread, something is amiss, and not all can be explained away as a freehub issue.

If it was a feehub issue, freewheeling alone would present an issue which would be noticeable. But beyond about 16mph, there is a discernible effect at play that appears to be drag of some sort.
It was such an odd sensation at the time made me take notice. But i only freewheels for a shortish distance(say 300m) so slowed down, pedaled etc so kind of dismissed it.
.

can you try someone elses ( who doesnt experience this phenomenom) bike with the same motor and see how it compares to yours?

this:-

The other day im cycling home, going down a slight incline on a road, freewheeling at about 18mph without peddling. I start to pedal, the speed drops to maybe 17 or 16 1/2mph, i stop pedaling it increases again. I can physically feel the bike being held back.

is not possible.

it amazes me when you see these guys on YouTube doing trails on ebikes and comingout of a berm and pedalling as if it’s nothing

it is nothing - well as nothing as pedalling a 25kg full sus mountain bike, with knobbly tyres , and very active suspension,at 16+mph, ever can be. Seriously though - try making yourself ride at a higher cadence - ie force yourself to be in lower gears - dont rely on the torque of the motor to pull the bike along because when it cuts out you'll really feel the fact it has cut out..
 
Last edited:

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
I should point out im in my 50's :LOL: so maybe 20 years ago i wouldnt have noticed it, and likely 20 years ago i wouldnt have even considered an ebike, were todays spec stuff available.
Probably at that time doing 250+ml a week, averaging 15-20mph more often than not. Saddles were for girls, and sweat and burn a staple diet.

How the mighty have fallen :LOL:
 

Growmac

Well-known member
Subscriber
Dec 4, 2020
375
389
Wilts, UK
Well thats the effect i found. Freehub is fine, bikes running fine, and thats certainly what feels like.
You're just experiencing what a heavy bike and soft tyres feels like without assistance. The motor cannot physically put drag on the bike when freewheeling, it can only fail to provide assistance, or provide resistance to your turning the cranks.
 

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
You're just experiencing what a heavy bike and soft tyres feels like without assistance.
Im on a downward incline. Heavy bikes freewheeling downhill accelerate. Pedaling from there you would or should feel less drag and it should cause you to increase speed, not have the speedometer go the other way.
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,748
20,422
Brittany, France
Im on a downward incline. Heavy bikes freewheeling downhill accelerate. Pedaling from there you would or should feel less drag and it should cause you to increase speed, not have the speedometer go the other way.
As others have said ... this just isn't possible. :-(

If you're on a descent and the bike is moving at for example 10mph, the back wheel can turn at whatever speed it wants. The cassette won't turn because the freehub separates them.

If you then Pedal - slowly - the cassette will turn, but it will be turning slower than the freehub/wheel so still won't engage, your efforts are only turning the cassette. If you pedal faster - so the cassette turns faster than the freehub, then it will engage and your energy will be transferred into the wheel - where you will either maintain speed if you manage to apply exactly the same pressure as the speed of the wheel, or accelerate.

You can't engage the freehub and cause a braking effect, it's a ratchet, it's physically impossible. If it was, you could have re-gen on mid motored bikes - but you don't and you can't. Unless you lock out the freehub and have the cassette and chain constantly moving with the wheel.

If you look down and your chain is moving when you're not pedalling, then there's a fault with your free hub. You can emulate this by passing a couple of zip ties through the back of the cassette and attach it to spokes. Then your chain will be constantly moving (so you can change gears even when not pedalling.. :) ... or saw through your leg when not paying attention .. 😭 ) If you do this, then the chainring will be constantly engaged and only the motor clutch will act as the freehub separating the motor from the wheel.
 

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
Very analytical Zim, but alas I didn't start his thread, im only commenting from a personal perspective, and as yet haven't had time to fully explore all the aspects.
Im, sure thought it's something to do with something else, or maybe its the environmental affects of the physicality of riding a bike for the last 30 years and experiencing a different sensation. I could even surmise muscle memory is playing a part.

Thanks though for that breakdown, I think I speak for many in congratulating the time you've put in here.

Perhaps an award is needed.🥇
 
Last edited:

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,066
4,585
Weymouth
That's inevitable - when you turn the pedals the motor is powered up - but not engaged because of the cut-off so you get the passive drag of the motor applied.

When you're not pedalling the only resistance you have is the freehub spinning away as the crank isn't moving.
Thats wrong I reckon. The motor cut off is not achieved by activating a clutch, it is achieved by switching off current from the battery. I believe on most systems that cut off is in fact a fairly quick ramping down of wattage rather than a sudden cut off to zero amps.
Assuming the bike is a bove the cut off speed , if you then start pedalling, all you are activating is the drivetrain plus of course the motor crankshaft complete with torque sensor and bearings ( including the sprag bearing). The crank cannot drive the motor.
It is possible you have a problem on the motor crankshaft.....e.g tight bearing.

(nb i differentiate between the electric motor and the rest of the internal drivetrain contained within the overall motor housing)
 

rod9301

Member
Oct 10, 2020
143
70
US
Depends really ... if you have to keep up with mates on non-eBikes on the downhills its a lot of work spending the whole time with the extra friction. My local trails vast majority of the downs I'm faster on an analogue bike
There's no extra friction on the downhill
 

2WheelsNot4

E*POWAH Master
Oct 17, 2021
889
682
Scotland
`Then the feeling must be down to friction when pedaling beyond the 15.5mph limit. The motor should be off,so the effct im feeling must be resistance coming from the motor.
 

Chiefworm

Member
Dec 27, 2021
46
31
United Kingdom
Sorry to jump on this or restart but did anyone get to the bottom of this issue? I ask as I have a new Orbea Wild and it feels exactly like this, like riding with brakes on! Not all the time but most of the time. In every mode and below 16mph. I have ridden Treks and Whytes and neither felt like this. Uphill on the flats etc, feels like it’s got an internal brake or the cut off is 10mph.
 

8bit Barry

New Member
Jan 10, 2024
41
21
Devon
I originally purchased my eMTB because I had a worsening hip problem that was causing pain, exacerbated by cycling. It was a game changer! since purchasing the bike I have used Tour mode as an absolute minimum. After reading this thread I tried Eco mode. It was a real struggle and felt like I was riding through thick treacle. It seemed much worse than riding my old mtb, and I was riding with assistance!
This was caused by many things, such as weight of bike, thickness of tyres, my (un)fitness etc.
One thing it was not caused by was friction or resistance of the motor, because the ride was assisted.
I would almost guarantee the same issues would be causing what you are describing.
I tweaked ECO mode by pushing the power up to +3 in the Flow app and that sorted it.
 

arTNC

New Member
Feb 1, 2024
68
116
Texas
Sorry to jump on this or restart but did anyone get to the bottom of this issue? I ask as I have a new Orbea Wild and it feels exactly like this, like riding with brakes on! Not all the time but most of the time. In every mode and below 16mph. I have ridden Treks and Whytes and neither felt like this. Uphill on the flats etc, feels like it’s got an internal brake or the cut off is 10mph.
This is very common, and it's not friction from the motor. It's just the cutting out of the motor and the rider now doing all or most of the work of pedaling a very heavy bike. I agree that it does feel like drag from the motor, but it's just a pronounced psychological impression you get...speaking only on the gen 4 Bosch motor...not sure about others.

While overall I'm much more pleased with how fast my Trek Rail 7 is over my 2003 Santa Cruz Bullit/Bafang mid-drive home build, I do miss hitting wide open flats or shooting up a climb at 20+ mph. I've done all allowed on the software at the shop for max power out of the Bosch, but this dropoff/cutoff of power at speed is natural and now it's just you hammering the pedals until speed drops. Obviously it helps to drop a gear or two, but then so does speed, so...

The solution if it's that annoying is one of the derestricting devices which like the Bafang allows manipulation of the top speed. My Bosch motor has slightly better and consistent acceleration over the Bafang, and the bike is faster on my main local trail, but I do miss the continued power feed as I approach 20 mph in a few of the faster spots on the trail. I like the rest of the power curve of the Bosch and would really only consider a slightly faster top speed. I ride in "Turbo", but the power is plenty for me in that mode with the exception of that 20 mph limitation.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,066
4,585
Weymouth
I can assure those that feel they are experiencing motor drag once the assist limit is reached is a myth! I once had a controller fault where the bike depowered completely but initially the motor did not disconnect. I could hardly push the bike along let alone pedal it!!
The "drag" experienced once the motor cuts out is due to a number of factors all of which when combined can be significant. Soft compound, slow rolling, heavy tyres...probably with low pressures are the biggest factor, but bike weight and loss of pedalling efficiency due to the kinematics of the suspended rear triangle also contribute.
 

irie

E*POWAH Elite World Champion
Subscriber
May 2, 2022
1,861
1,779
Chichester, W.Sussex, UK
I can assure those that feel they are experiencing motor drag once the assist limit is reached is a myth! I once had a controller fault where the bike depowered completely but initially the motor did not disconnect. I could hardly push the bike along let alone pedal it!!
The "drag" experienced once the motor cuts out is due to a number of factors all of which when combined can be significant. Soft compound, slow rolling, heavy tyres...probably with low pressures are the biggest factor, but bike weight and loss of pedalling efficiency due to the kinematics of the suspended rear triangle also contribute.
When the motor cuts out wind resistance becomes a key issue.
 

EMTB Forums

Since 2018

The World's largest electric mountain bike community.

513K
Messages
25,120
Members
Join Our Community

Latest articles


Top