Bosch CX gen 5 motor drag

[Kedde76]

Hello

I plan to retire my Kenevo SL spring next year and considering the replcement bike to be one fitted with a Bosch CX gen 5 motor.

But how much motor drag does the new Gen 5 motor have when pedaling above the motor speed limit? I am a bit concerned about this as trail speed on my local trails are abve the limit and trails are quite flat. I really need to pedal hard already on the KSL.

The kenevo SL motor de-couples completely through a sprag clutch, but when searching the web for info on the gen 5 Bosch motor, I cannot find anything concrete and firm info on the subject.

Safe riding

Christian

 

[rod9301]

With the Bosch you have to pedal pretty hard when you get over their speed limit

 

[irie]

When you get past motor cut-out speed wind resistance creates a lot of drag.

 

[steve_sordy]

@Kedde76 I have never owned a Bosch motored bike, but I have read many similar questions on here. The consensus as it appears to me is that the various motors cause only minimal drag, almost un-noticeable in fact. What riders feel is the drag from wide heavy and sticky tyres. Also having to overcome wind resistance unaided. Plus having to propel the weight of the bike of course! All of this is why muscle powered bikes have focussed on light weight, narrow high-pressure tyres, and lycra!

The test is to put your bike on the work stand and drop the chain off the ring. Then turn the cranks. Even with the motor off there should be minimal drag. The cranks should spin freely. I have never done that test myself because I have to remove the chain guide but more the fact that I don't feel that my motor is draggy. But I think I'll do it next time I'm in the garage just to see for myself.

 

[irie]

I have never done that test myself because I have to remove the chain guide but more the fact that I don't feel that my motor is draggy. But I think I'll do it next time I'm in the garage just to see for myself.

Have flip up chain guides (Reverse Components) so easy to do this. No drag from our Bosch CX Gen4 motors.

 

[2WHLFUN]

Ahhh, pedal kickback and motor drag are mysteries we'll never get answers to... lol

 

[RustyIron]

But I think I'll do it next time I'm in the garage just to see for myself.

Ok, I just went down to the garage and did that. The drag from my Gen 4 motor is a little more than you'd get from the bottom bracket on a high-end Amish bike, but not substantially more.

When you see folks on the interwebs complaining about "motor drag," they're invariably the ones who have never ridden a heavy Amish bike, never ridden slow-rolling tires on an Amish bike, and have never ridden an Amish bike fast. When you're peddling a heavy, slow-rolling Amish bike fast, it's like riding Dawn French on a steep muddy uphill after a big Thanksgiving dinner.

Sure, there might be someone out there who has a seized freehub, wonky Sprag clutch, or worn out bearings, but I'd wager that is rarely the case.

 

[Streddaz]

Ok, I just went down to the garage and did that. The drag from my Gen 4 motor is a little more than you'd get from the bottom bracket on a high-end Amish bike, but not substantially more.

When you see folks on the interwebs complaining about "motor drag," they're invariably the ones who have never ridden a heavy Amish bike, never ridden slow-rolling tires on an Amish bike, and have never ridden an Amish bike fast. When you're peddling a heavy, slow-rolling Amish bike fast, it's like riding Dawn French on a steep muddy uphill after a big Thanksgiving dinner.

Sure, there might be someone out there who has a seized freehub, wonky Sprag clutch, or worn out bearings, but I'd wager that is rarely the case.


View attachment 150987

Yes, with all the modern motors, there should be very minimal motor drag, and that drag it mainly due to a little bit of friction in the motor clutch/freehub and the bearings and seals for the cranks.
One thing to keep in mind when going from a low powered SL bike to a full powered bike, is that the perceived drag is greater because the assistance it greater, so when that motor cuts out there's a bigger assistance drop.
Also, the bike will most likely be heavier, and possibly have heavier, slower rolling tyres.

 

[2WHLFUN]

Yes, with all the modern motors, there should be very minimal motor drag, and that drag it mainly due to a little bit of friction in the motor clutch/freehub and the bearings and seals for the cranks.
One thing to keep in mind when going from a low powered SL bike to a full powered bike, is that the perceived drag is greater because the assistance it greater, so when that motor cuts out there's a bigger assistance drop.
Also, the bike will most likely be heavier, and possibly have heavier, slower rolling tyres.

Yep, on the perfect grade and you're sprinting as soon as the motor cuts off it feels like you are hitting a wall! If you go onto level ground turn off the motor completely, gear down a little and it should feel like any other bike. It's a trippy feeling on both counts.

 

[Rando_12345]

Just to add another point, I have an ebike with heavy dh tyres, you need to pedal constantly even on flat to keep speed up. My wife has a city ebike with the same motor and weight, but slick tyres, her bike speeds up, coasts and goes above motor cuttoff so easily.

 

[RichMorr]

Just got the schwalbe Alberts radial tyres gravity pro soft rear and trail pro ultra soft at the front and they are horrendous for drag, 2 rides and I hate them. Going to experiment with pressures, if still horrible my eliminator and butcher will be back on and a waste of £140

 

[Weeksy]

Just got the schwalbe Alberts radial tyres gravity pro soft rear and trail pro ultra soft at the front and they are horrendous for drag, 2 rides and I hate them. Going to experiment with pressures, if still horrible my eliminator and butcher will be back on and a waste of £140

I'll give you £40

 

[RichMorr]

I'll give you £40

I wouldn’t inflict their horrendous on you

 

[Weeksy]

I wouldn’t inflict their horrendous on you

My lad races DH, he doesn't pedal. Grip beats rolling speed.
We've just had some Shreddas arrive.

 

[irie]

Just got the schwalbe Alberts radial tyres gravity pro soft rear and trail pro ultra soft at the front and they are horrendous for drag, 2 rides and I hate them. Going to experiment with pressures, if still horrible my eliminator and butcher will be back on and a waste of £140

Few weeks ago bought Maxxis High Roller 3's for our bikes, did consider Schwalbe radials but they weren't available. Looks like a bullet dodged. TBH if the contact patch is as big as Schwalbe says then I guess it's not surprising that they are ultra draggy.

Edit: after trying different pressures settled on front: 22 psi, rear: 24 psi.

 

[RichMorr]

Few weeks ago bought Maxxis High Roller 3's for our bikes, did consider Schwalbe radials but they weren't available. Looks like a bullet dodged. TBH if the contact patch is as big as Schwalbe says then I guess it's not surprising that they are ultra draggy.

This is why I got the Albert’s rather than Mary’s as the tread pattern was supposed to mitigate the drag if you believe the marketing manager. Reading about them, tires pressure is so important with them so need to have play about before I take them off

 

[Weeksy]

This is why I got the Albert’s rather than Mary’s as the tread pattern was supposed to mitigate the drag if you believe the marketing manager. Reading about them, tires pressure is so important with them so need to have play about before I take them off

I get the impression for trails you want about 27f 29r roughly. When we test ours we'll go somewhere round that for him.
Funnily I went out on my Fuel today with super soft DH Contis on today, they were horrific too! I was testing them for fod this weekend but no no no.

 

[Weeksy]

IMG_20241129_142437 by Steve Weeks, on Flickr

 

[RichMorr]

I get the impression for trails you want about 27f 29r roughly. When we test ours we'll go somewhere round that for him.
Funnily I went out on my Fuel today with super soft DH Contis on today, they were horrific too! I was testing them for fod this weekend but no no no.

I’ve increased the pressure, bought a digital gauge and set it at 27 front and 33 rear. See how they are any better or are they off to the bin.

 

[Weeksy]

I’ve increased the pressure, bought a digital gauge and set it at 27 front and 33 rear. See how they are any better or are they off to the bin.

or £40

 

[Lee Dove]

I have a Gen 5 and it has virtually no drag when not driving.

 

[franciscoasismm]

When you get past motor cut-out speed wind resistance creates a lot of drag.

 

[irie]

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I could be be wrong @franciscoasismm but I get the distinct impression you want to tell me something?

 

[Eagleboy64]

My Bosch Gen 4 motor drags when there is no power and I pedal, but it free wheels with no drag as long as I keep my cranks in one place and don't pedal.

 

[HandsomeDanNZ]

I think the whole drag thing is relative.
Went for a ride with my son, who has a fabulous Banshee enduro rig (analogue) that he loves riding, but part way through the ride, I wanted him to see what my eBike was like to ride up a hill we both know and loathe - not only did he enjoy it, but I got a first-hand experience of what the whole "experiencing drag when over the cutoff" is like.
I jumped on his bike and it immediately felt like his bike needed a lube, some grease and maybe the brakes to be disengaged. The feeling of drag was astonishing...and yet, his bike is beautifully maintained, lightweight and normally great to ride.

I actually think a lof of the drag that is felt is a combo of sticky, high volume tyres, heavy bike and "compared to having assistance, this is really draggy".
Just my 2c.

 

[lar1337]

Just got the schwalbe Alberts radial tyres gravity pro soft rear and trail pro ultra soft at the front and they are horrendous for drag, 2 rides and I hate them. Going to experiment with pressures, if still horrible my eliminator and butcher will be back on and a waste of £140

I'll buy them off you

 

[RichMorr]

I'll buy them off you

I’ve had a play about with the tire pressure and it’s completely different ride no drag, so I’ll be keeping them. My next set I will definitely get the trail casing on the rear as the weight isn’t the best. Probably do MM front trail ultra soft and Albert trail soft rear.

 

[Weeksy]

I’ve had a play about with the tire pressure and it’s completely different ride no drag, so I’ll be keeping them. My next set I will definitely get the trail casing on the rear as the weight isn’t the best. Probably do MM front trail ultra soft and Albert trail soft rear.

And what did you settle on ?

 

[RichMorr]

And what did you settle on ?

I got the Albert gravity soft on the rear with 32 psi up from 27 and Albert tail ultra soft on the front at 27 psi from 25. Spent most of sat going up and down messing with tyre pressure going up and down a different hills. Very sad but sorted

 

[MotoGPnut]

@Kedde76 I have never owned a Bosch motored bike, but I have read many similar questions on here. The consensus as it appears to me is that the various motors cause only minimal drag, almost un-noticeable in fact. What riders feel is the drag from wide heavy and sticky tyres. Also having to overcome wind resistance unaided. Plus having to propel the weight of the bike of course! All of this is why muscle powered bikes have focussed on light weight, narrow high-pressure tyres, and lycra!

The test is to put your bike on the work stand and drop the chain off the ring. Then turn the cranks. Even with the motor off there should be minimal drag. The cranks should spin freely. I have never done that test myself because I have to remove the chain guide but more the fact that I don't feel that my motor is draggy. But I think I'll do it next time I'm in the garage just to see for myself.

I think this is absolutely correct. I have not removed the chain, but when I put my bike up on the stand there is virtually no resistance turning the cranks with the motor off.