What does a bit of extra weight on an ebike actually do?

[Gubbins]

I weight 81kg and my bike around 22kg which is approximately 103kg in total. Today I bought 4 litres of milk (4kg) and put it all in one pannier which should be really noticeable with all the extra weight on one side but once moving I didn't notice much difference. It didn't seem to need more effort from me going uphill, accelerated away from junctions as is usual and I was still able to ride just over the cutoff on the flat. At 81kg I am not exactly a lightweight but many weigh more which begs the question. Leaving aside the new carbon ultralight bikes that few are likely to buy then the there is 4 to 5kg difference in light/heavy ebikes. So does this 4 or 5 extra kilos in e-bike weight actually make that much difference?

 

[Neily71]

I weight 81kg and my bike around 22kg which is approximately 103kg in total. Today I bought 4 litres of milk (4kg) and put it all in one pannier which should be really noticeable with all the extra weight on one side but once moving I didn't notice much difference. It didn't seem to need more effort from me going uphill, accelerated away from junctions as is usual and I was still able to ride just over the cutoff on the flat. At 81kg I am not exactly a lightweight but many weigh more which begs the question. Leaving aside the new carbon ultralight bikes that few are likely to buy then the there is 4 to 5kg difference in light/heavy ebikes. So does this 4 or 5 extra kilos in e-bike weight actually make that much difference?

Probably battery life will be affected the most as motor having to work harder to perform the same with the extra weight. So my guess would be lighter the bike and rider the better the range? Somebody will correct me though no doubt [emoji16]

Sent from my G3221 using Tapatalk

 

[flecc]

Leaving aside the new carbon ultralight bikes that few are likely to buy then the there is 4 to 5kg difference in light/heavy ebikes. So does this 4 or 5 extra kilos in e-bike weight actually make that much difference?

It does make a difference, and there's two factors to consider.

While your extra 5 kilos is under 5% more than the gross weight, the important thing is that the 5 kilos plus 22 kilo bike is 27 kilos of dead weight, your 81 kilos is living weight which your body has adapted to by growing musculature to suit.

So for riding overall you should be excluded from the comparison, the 5 kilos is added to the 22 kilos of the bike, so that's 23% extra dead weight, not under 5%.
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[Gubbins]

What difference in range would you expect a 25% increase to make? (Rounding up). It would need more effort to climb but also gain extra momentum when going down. My reason for asking is that my next bike weighs an astonishing 31kg and I am sort of clutching at straws..

It does make a difference, and there's two factors to consider.

While your extra 5 kilos is under 5% more than the gross weight, the important thing is that the 5 kilos plus 22 kilo bike is 27 kilos of dead weight, your 81 kilos is living weight which your body has adapted to by growing musculature to suit.

So for riding overall you should be excluded from the comparison, the 5 kilos is added to the 22 kilos of the bike, so that's 23% extra dead weight, not under 5%.
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[flecc]

What difference in range would you expect a 25% increase to make? (Rounding up). It would need more effort to climb but also gain extra momentum when going down. My reason for asking is that my next bike weighs an astonishing 31kg and I am sort of clutching at straws..

I don't think there'd be a huge difference since weight makes virtually no difference of the flat, just very slightly increasing rolling resistance and frictions. As you say, the downhills compensate the uphills to some extent, especially if you let the bike have its head and minimise use of the brakes, wasting energy. It wasn't so long ago that most e-bikes commonly weighed between 28 kilos and 40 kilos, so your 31 kilos is not so bad. It will feel ponderous without power of course, and the extra weight will have a slight effect on it's feel when under power, but you'll soon adapt.

Just think of the riders of unpowered 140 kilo pedicabs (without any passengers) and think how lucky you are with just 31 to deal with.
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[Gubbins]

I don't think there'd be a huge difference since weight makes virtually no difference of the flat, just very slightly increasing rolling resistance and frictions. As you say, the downhills compensate the uphills to some extent, especially if you let the bike have its head and minimise use of the brakes, wasting energy. It wasn't so long ago that most e-bikes commonly weighed between 28 kilos and 40 kilos, so your 31 kilos is not so bad. It will feel ponderous without power of course, and the extra weight will have a slight effect on it's feel when under power, but you'll soon adapt.
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just dont put it on a roof rack!!

 

[Woosh]

just dont put it on a roof rack!!

Although I read somewhere that it is illegal putting an e-bike on a roof rack, I did try it today. It was very, very hard to lift an e-bike, with or without battery, high enough to go on the roof rack. Please don't try.

 

[Gubbins]

Although I read somewhere that it is illegal putting an e-bike on a roof rack, I did try it today. It was very, very hard to lift an e-bike, with or without battery, high enough to go on the roof rack. Please don't try.

Was only joking. If i get to the point of travelling with a bike i will have a towball fitted with a thule carrier.

 

[anotherkiwi]

My trike weighs about 17 kg (constructor number), I have added about 1 kg of tyres, a rack and carry panniers with tools, lock, water and raingear. Add lights, a bell, a horn... So not far off 20 odd kg at the least. It is a pig to get going, so I am pretty good public for ads touting trikes that weigh 10 kg or less

As flecc says above it is dead weight, it certainly ain't pedaling for you! I have never dared weigh my Number Two but it is certainly heavier than my first build which I did weigh at slightly under 21 kg. But N°2 has nice big 700C wheels and downhills like a motorbike, sure and stable despite a crappy front fork which can be wishy-washy when pushed to its limit.

You will notice the 31 kg when you are stopped but not when the motor is assisting you.

 

[soundwave]

You will notice the 31 kg when you are stopped but not when the motor is assisting you.

 

[Gubbins]

You will notice the 31 kg when you are stopped but not when the motor is assisting you.

Now that is fat shaming!

 

[soundwave]

my sis wants some of those but she is to fat lol

 

[MikeS]

Was only joking. If i get to the point of travelling with a bike i will have a towball fitted with a thule carrier.

I bought the Velo 925 compact from Halfords (about £60 cheaper than anywhere else). Lifting the ebike on to the rack can be tricky until you work out a consistent way to do it (position of pedal and clamp etc). I was going to buy the ramp thing but found that I could get the same effect just rolling the front then the back wheel up on to the rack without any ramp.
Superb piece of kit.
Mike

 

[Nev]

Good question Gubbins I wonder if the answer to your question might actually depend on what ebike we are talking about. Let’s consider two electric assist bikes.


Bike A, decent spec hard tail eMTB with bosch Performance Line CX motor with torque and cadence sensors and weight of say 22 kg.


Bike B, top of the range electric assist racing bike, carbon frame etc. And weight of say 10 kg.


Now let’s assume as per your OP that we increase the weight of both bikes by 4 kg, would we notice much difference. Starting with Bike A.


Bike A

This bike has increased its weight by about 18.5% but I suspect we are not going to notice much difference. As flecc has already mentioned, it’s unlikely we will feel this extra weight when riding along on the flat. On down hill sections it will actually help us, so it’s only up hill we need to consider.


Looking at the spec of the CX motor in the highest setting it provides 300% support level. I assume this means that whatever the rider puts in, the motor puts in three times as much (let me know if this is incorrect). So instead of having to power the extra 4 kg up hill, the effect of the motor means it’s more like we have to cope with an extra 1 kg, the other 3 kg are being dealt with by the motor.


Bike B

This bike has increased its weight by 40%, I suspect one would notice this increase. I haven’t looked at any specs for the motor of this type of bike, but my guess would be it provides support to about 100% (if anyone knows let me know). I think this means we now have to cope with an extra 2kg when riding up hill, so double the weight that Bike A presented.


I think there is also another consideration and is possibly the reason why manufacturers have recently being trying to lessen the weight of e racing bikes. Many people may well be able to ride a 10 kg e racer up a slight incline at around 18 mph (ie just above the motor cut off speed), increase the weight to 14 kg and lots of those same people may now have to ride up at around the cut off speed of 15.5 mph.

 

[flecc]

Looking at the spec of the CX motor in the highest setting it provides 300% support level. I assume this means that whatever the rider puts in, the motor puts in three times as much (let me know if this is incorrect). So instead of having to power the extra 4 kg up hill, the effect of the motor means it’s more like we have to cope with an extra 1 kg, the other 3 kg are being dealt with by the motor.


Bike B

This bike has increased its weight by 40%, I suspect one would notice this increase. I haven’t looked at any specs for the motor of this type of bike, but my guess would be it provides support to about 100% (if anyone knows let me know). I think this means we now have to cope with an extra 2kg when riding up hill, so double the weight that Bike A presented.

Those are right. The tiny in-seat-tube motor that's ideal for the light bike B had 100 watts net claimed when it was released, the maker later claiming an unlikely 200 watts which I suspect was the marketing department version. However there are some small and light hub motors that can output very much more, though the battery necessary to use that power will up the bike B weight quite a lot.
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[Gubbins]

Those are right. The tiny in-seat-tube motor that's ideal for the light bike B had 100 watts net claimed when it was released, the maker later claiming an unlikely 200 watts which I suspect was the marketing department version. However there are some small and light hub motors that can output very much more, though the battery necessary to use that power will up the bike B weight quite a lot.
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I was thinking about bike C.
Well made, Bosch cx powered hard tail with all the trimmings weighing in at 31kg in comparison with bike A at 22kg. That's 9 bags of sugar added in... I use sugar as a reference cos I can more easily imagine carying 9 bags of sugar...

 

[soundwave]

get 9 bags of sugar n put them in a back pack n get on ur bike going down and up that hill off road in ur vids.

then time it with out the pack, if you have any brakes left lol.

 

[Nev]

Which bike are you thinking of Gubbins? 31kg seems rather heavy for a well made hard tail. Is it one that has a double battery?

 

[Gubbins]

My problem is I buy with my heart not my head. I bought a full sus emtb which was great but when the novelty wore off I saw it's limitations and tried to turn it into what I actually want from a bike which TBH can't be done. So I made a list of what I would like and am now looking for a bike that ticks all my boxes which are..
Ideally Bosch electronics, hub gears, ff mudguards and lights, double battery option, bottle cage mount, rear rack and kickstand, suspension (not necessarily FS) integrated battery(s) and ability to do mild off road.
On top if that it needs to be aesthetically pleasing so the short list is very short.
So far the RM supercharger totaly fits my bill but is heavy, so hoping next year brings some new stuff to the table.

 

[Trevormonty]

My problem is I buy with my heart not my head. I bought a full sus emtb which was great but when the novelty wore off I saw it's limitations and tried to turn it into what I actually want from a bike which TBH can't be done. So I made a list of what I would like and am now looking for a bike that ticks all my boxes which are..
Ideally Bosch electronics, hub gears, ff mudguards and lights, double battery option, bottle cage mount, rear rack and kickstand, suspension (not necessarily FS) integrated battery(s) and ability to do mild off road.
On top if that it needs to be aesthetically pleasing so the short list is very short.
So far the RM supercharger totaly fits my bill but is heavy, so hoping next year brings some new stuff to the table.

Few brands have 2019 FS and HT bikes with rack, full mudguards, stand and lights ie SUV of ebikes, which R&M has being doing for a while. Checkout Gaint, Bulls and Trek full range.