Bosch Performance CX Drag test #001


Wiltshire Warrior

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OK so when I got my Moterra 10 days ago I said that it pedalled effortlessly with the motor off and the heavy wheels and bike weight were Accounting for all of the extra effort required to pedal it when compared to a 25LB MTB.

I stand by that

Today I have rough tested the motor "drag" which is often mentioned but never proved.

With the chain off I hung weights from one pedal with the cranks horizontal until the crank dropped when I reached 100g weight. Movement is from 90 deg to about 130 deg in both examples here.

XT Non E bike resistance 40g test:

Bosch Perf CX resistance test 100g:

So the effective Rotational Resistance is 60g more on Bosch compared to Normal XT. So to negate this all one needs to do is find a 60g weight saving in either - pedals, chain, wheels ect to mitigate this.

So can you do the same for Brose or Shimano with a 40g weight to see if they really are the same as none powered bikes
 

Wiltshire Warrior

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Just swapped the Time Freerides for normal plastic Times saving 60g on each pedal. next XC ride is tomorrow night - I doubt I will feel the difference - but the battery will.
 

MattyB

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Sorry, but whilst interesting I don't think your test is completely valid. You are testing static friction, but it's kinetic/dynamic friction that will be in play when you are pedalling the bike unassisted at over 25kph (more info here). You would need a way to measure the resistance whilst travelling along (or on a turbo) to be sure that the magnitudes of the forces measured at rest are replicated whilst riding.
 
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R120

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You only have to ride a Bosch back to back with another motor to “prove “ the issue. We have Bosch and Shimano motors in my family and it’s night and day, and again if you test the Brose against the shimano and Bosch you will notice the pretty much total lack of drag of the Brose.

The Bosch is just the oldest design on the market, and it’s performance reflects that.
 

Gary

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So the effective Rotational Resistance is 60g more on Bosch compared to Normal XT. So to negate this all one needs to do is find a 60g weight saving in either - pedals, chain, wheels ect to mitigate this.
Wow!

this is mindblowingly bad science.
Just swapped the Time Freerides for normal plastic Times saving 60g on each pedal. next XC ride is tomorrow night - I doubt I will feel the difference - but the battery will.
no. It won't.

Ride your bike
 
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Doomanic

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Take the chain off both bikes, prop yourself up against a wall or fence and just pedal at various different cadences. If you still can’t feel the difference between a Bosch motor and no motor there’s no hope for you.

Or just ride, and enjoy, your bike.
 

Sbozzy

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Well this helps me decide once and for all I don’t want a Bosch system. Too many reports of the drag and the last thing I want when spending a lot of money on my first emtb is drag when I hit the limit or the battery dies.
I’ve tested a Brose Motor and loved it, not tested the shimano yet but Bosch it def out.
 
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Wiltshire Warrior

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Well this helps me decide once and for all I don’t want a Bosch system. Too many reports of the drag and the last thing I want when spending a lot of money on my first emtb is drag when I hit the limit or the battery dies.
I’ve tested a Brose Motor and loved it, not tested the shimano yet but Bosch it def out.
For fun I rode mine last night (dog walk) 3 miles flatish - "switched off" no problem - the drag is very minimal and I wouldnt let all the fuss put you off.

Also on ECO it will last for 4-5 hours where I live as we only do about 1000 in 2 hours - not very big hills!

I am sure the Brose and Shimano are equally as good...
 

Marke

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I am happy with my bosch because i read it feels like the most powerful of the most popular brands. Also there are guys selling selling replacement bearings and fitting instructions for when/ if it fails out of warranty. 30 quid ish i think. Also see the tuning section for details on how to remove the drag over 15mph.
 

Gary

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I am happy with my bosch because i read it feels like the most powerful of the most popular brands. Also there are guys selling selling replacement bearings and fitting instructions for when/ if it fails out of warranty. 30 quid ish i think. Also see the tuning section for details on how to remove the drag over 15mph.
This is great news. Sorry to go OT but have you heard of anyone offering similar service/info for Shimano motors?
 
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Marke

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This is great news. Sorry to go OT but have you heard of anyone offering similar service/info for Shimano motors?
No, i suspect alot owners with less popular motors will struggle with this issue further down the line. One reason i bought bosch
 

Marke

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The two year warranty was one of the reasons I bought Shimano.
I think most of the major manufacturers offer a 2 year warranty on the motor - bosch does. I think replacement bosch motor is about 600 quid ... 30 quid sounds better. Knowing my luck the damn think will fail at 2 years 1sec :)