Motor drag? What's all the fuss?

Akiwi

🐸 Kermit Elite 🐸
Feb 6, 2019
986
1,286
Olching, Germany
I am constantly hearing about "Motor drag" and how so many people put so much emphasis on this when selecting their e-bikes. I have been riding e-Mountain bikes for 2 years now. I started with the Focus Jam 2 with Shimano motor for 1 year, and then changed to a Cube 160 Race with Bosch motor, and I realy don't notice any difference. I accept that because of the gearbox, there is probably a little more drag, but I can't notice it.
I ride a huge amount with the motor off, as I tend to try to extend my battery life as much as possible, or give myself a workout as much as possible. If it's flat, then toggle to off. If there is a hill, then toggle to Eco to make life easy. Then when the going gets tough, use the other modes.
Are there any actual statistics as to how much drag a bosh motor creates? I think I remember reading 4% somewhere, which is probably less than most people can feel, particularly on Fat + sized soft compound tires.
Just thought I'd say.
 

All Mountain Coaching

E*POWAH Elite
Oct 3, 2018
1,332
980
GB
I can definitely feel it. It's a little inconsistent too. Depends on speed and cadence. Sometimes it's as if the more you pedal, the more it slows you down. I've also noticed that when you stop pedalling to freewheel, it speeds up, so there is definitely resistance.

I had to pedal with it off for sometime yesterday as the bike turned off and would not turn back on
 

ggx

Well-known member
Dec 10, 2018
673
439
Sintra
Hi,
usualy I ride in assist modes (bosch cx), but yesterday made lot´s off riding in off. The big drag I feel is the increased weight, expecialy when uphill .
 

Akiwi

🐸 Kermit Elite 🐸
Feb 6, 2019
986
1,286
Olching, Germany
I can definitely feel it. It's a little inconsistent too. Depends on speed and cadence. Sometimes it's as if the more you pedal, the more it slows you down. I've also noticed that when you stop pedalling to freewheel, it speeds up, so there is definitely resistance.

I had to pedal with it off for sometime yesterday as the bike turned off and would not turn back on
Are you talking about the Brose or the Bosch motor?
And turning off and not turning back on is about the most annoying thing that can happen on an e bike. That is the reason I got rid of my Focus with Shimano motor. It did that often.
 

Akiwi

🐸 Kermit Elite 🐸
Feb 6, 2019
986
1,286
Olching, Germany
Hi,
usualy I ride in assist modes (bosch cx), but yesterday made lot´s off riding in off. The big drag I feel is the increased weight, expecialy when uphill .
Yes, definitely you feel the weight. But on the flat.. is it the motor or just the general drag of a heavy mountain bike with Fat tyres.
 

MattyB

E*POWAH Elite World Champion
Jul 11, 2018
1,266
1,279
Herts, UK
Yes, definitely you feel the weight. But on the flat.. is it the motor or just the general drag of a heavy mountain bike with Fat tyres.
If you ride a Bosch back to back with a Brose or Shimano the increased drag of the Bosch is pretty clear. However, I agree it is probably a factor whose importance is overstated for most people unless you need to spend a large amount of time transiting on flat roads or cinder paths to get to your local trails. More annoying (for me) is the small chainring that clogs with mud causing chain suck and wears quicker than a standard chainring.
 

R120

Moderator
Subscriber
Apr 13, 2018
7,819
9,185
Surrey
It really varys from bike to bike - TBH the main culprits of drag with the Bosch are Haibikes imo - the use of an idler wheel on some of their bikes means lots of drag when post the assistance.

If you rode a Cube for example, back to back with an idler wheel equipped Haibike, you would think they had different motors past the cut off.

Haibike_MY19_XDURO_NDURO_60.png
 

More-read-than-ride

Active member
Patreon
Jan 3, 2019
277
218
Spain
I just rode a Cube 160 action team (Bosch) and a week later the Lapierre overvolt 727i (Shimano).

To me, the Bosch definitely has noticably more drag, but on 27,5 x 2.8 minions, the effect of the drag of the tires is quite big on some surfaces and that means that the effect of the motor is less important. I think if you run 29x2,3 it becomes more important, but I have not tried. Weight will also be a factor.

In other words, I assume that is if you are a heavy rider, riding a heavy emtb (+23kgs) and wide tires, I would not worry about the motor drag very much unless you do lots of straights. However, if are a light rider and you ride a 20kg emtb on 29's with narrower tires, I think the effect will be pronounced.

Personally, I prefer the bosch. I think the power delivery and climbing charateristics outweigh the issue of the drag, but many people feel the opposite.

EDIT: Here are my impressiones of the two bikes.
Cube 160 Action Team first impressions. 9/10 - EMTB Forums
Lapierre overvolt 727i first impression. - EMTB Forums
 
Last edited:

HikerDave

Active member
Feb 9, 2019
220
201
Tempe
I am constantly hearing about "Motor drag" and how so many people put so much emphasis on this when selecting their e-bikes. I have been riding e-Mountain bikes for 2 years now. I started with the Focus Jam 2 with Shimano motor for 1 year, and then changed to a Cube 160 Race with Bosch motor, and I realy don't notice any difference. I accept that because of the gearbox, there is probably a little more drag, but I can't notice it.
I ride a huge amount with the motor off, as I tend to try to extend my battery life as much as possible, or give myself a workout as much as possible. If it's flat, then toggle to off. If there is a hill, then toggle to Eco to make life easy. Then when the going gets tough, use the other modes.
Are there any actual statistics as to how much drag a bosh motor creates? I think I remember reading 4% somewhere, which is probably less than most people can feel, particularly on Fat + sized soft compound tires.
Just thought I'd say.

Probably you'd have to measure motor drag by riding the bike with a power meter with and without the gearing and motor installed in the casing, which no one will ever do. So just make up a number.

My Haibike SDURO with Yamaha PW-SE motor has a lot of inertia in the motor, which I feel mostly riding through the park on the way to work when I sometimes turn off the assist. The odd thing about the drag / inertia is that it is inconsistent. Climbing a gentle grade with assist off I don't notice this as much; and I can ride a couple of hundred yards in the morning before I remember to turn on the bike.

I wouldn't want to pedal the bike any distance with the motor off; but I went 9 miles with the motor set at 50 percent assist and used 7 percent of the battery, so I'm not too worried about running out of juice.
 

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