Making an ebike more efficient for road rides

[Electric_Andy]

I think you are hoping to find a sweetspot that doesn't exist. An E-gravel bike is about as efficient as they get if you put slim road tyres on. You could plough a lot of time and money into making all these tweaks, and for very little gain. e.g I once had a hardtail MTB and found I wanted to do more road riding. I changed the tyres, altered the bars and seat, shaved off as much weight as I could. The only noticable difference was the rolling resistance of the tyres, and that's going from full on nobblies to slim jim baldies.

If you absolutely need more range then the only way to get significantly more is to get a bike with a larger battery, which of course would be heavier and not as road-focused. It's a bit like when a teen gets a 125cc and spends loads on fancy exhaust systems, premium fuel and racing engine oil...you only see about 2mph difference at the top end. Which can easily be wiped out by a slight headwind and a few pies the night before. The only real gain comes when you get a larger capacity bike

 

[N0bodyOfTheGoat]

I think the biggest factors by far are the climbs, the total weight of the ebike plus me, as well as the amount of motor assistance for a given duration.

Switching out the tyres, tubes and front wheel would reduce the ebike weight by approx a modest 1-1.5Kg.
Even though this switch is more for lowered rolling resistance and some aero gains, which should use less motor battery to reach 15.5mph and give me a bit more speed for my effort above that speed... Maybe 1mph?

I'm very slowly trying to work on my weight, I'm on the verge of dropping under 93Kg for the first time in two years.
The inability to exercise like I could before long covid, combined with taking Mertazapine/Sertraline for just over two years didn't help me at all. Back in January I briefly hit 98Kg.
From summer '17 to September '22, I was typically 75-80Kg and 95% of my best 20mins power was approx 290-320W.

Like I wrote yesterday, 25mins of 250W assist uses ~40% of the 248Wh battery and on my recent first 50-miler ebike ride, I only engaged turbo when I was prepared to ride at or beyond threshold (mainly on 3.5 Strava cat4 hills 260-350 feet).
I could use less turbo assistance, which will dramatically increase the battery range/duration, but the big unknown is how long beyond the recent 50-miler's 3hrs10mins I can manage even with the huge help of an ebike.

 

[N0bodyOfTheGoat]

I don't know anything about e-bikes but 16mph (nearly 26 km/h) strikes me as awfully fast.

Edit. Ignore me. I'm completely failing to appreciate the significance of the 15mph cut-off in all this. But I don't quite know what that significance is.

UK road legal ebikes attempt to give you motor assistance up to 25kph (~15.5mph).

How successful they are depends on factors like the Watts assistance amount (max 250W average over 30mins); wind direction and strength; how steep the road is; the combined weight of the rider and ebike; how much effort (Watts) the rider is putting out (some motor systems scale assist by pedalling torque, others by pedalling cadence).

Once you reach the motor cutoff speed, you're effectively riding a very heavy bike typically 15-30Kg, compared to a 7-9Kg racing snake road bike.

So someone ~70Kg on a 15Kg ebike could quite easily do ~140W, get 250W assistance in turbo and so be effectively riding at ~4.6W/Kg... Allowing them to ride steeper gradients at close to 15.5mph than a heavy rider like me at 93Kg.

But as soon as they go faster than ~15.5mph up a steady incline, they need to generate that 390W themselves to maintain speed.

A 70Kg rider on an ebike needs to generate more Watts above 15.5mph on a slope than a 70Kg rider on a light road bike, to produce the same effective W/Kg.

When riders don't suddenly ramp up their own power output as they approach and exceed the motor cutoff speed, when using high assistance levels, you get this very weird feeling like the brakes have been activated.

 

[IanSmithCSE]

Good afternoon,

I have been using my Ribble Ale, also x35, for my daily commute, 5 days a week, 18 miles each way for about 18 months.

Sadly I would suggest that apart from the tyre change there is very little that you can usefully do equipment wise.

The x35 system was originally marketed as Just enough power and was aimed at seriously fit riders wanting help going up mountains. This focus has been lost in much of the current marketing blurb and the low capacity battery pack skipped over.

The only thing that I have noticed is that I have a tendency to overgear much more on the e-bike than on my unpowered bikes as the motor can hide this.

For the last month or so I have been concentrating on using smaller gears and can almost get 4 legs, 72, miles out of a knackered battery with 188Wh or 80% of new capacity.

I mean really concentrating, small ring 34-11-32 up to about 23mph only then going to the big ring.

The other thing with the x35 is that it tapers power off as it approaches the cut of speed rather than bluntly cutting it off.

Finally I run 40/100/175W.

Although I think it is awful value for money maybe the range extender is the way to go. The total of the bike plus you isn’t going to change much with extra weight.

It also has the advantage of being simple to do and if it isn’t enough then there really isn’t anything else left to try.

Bye

Ian

 

[albion]

If you get 4 legs Ian, charging to 80% and doing 2 legs per charge will massively protect the battery. I always charge mine to 100, needing 100 for flexibility on leisure rides. But I charge to about 80 then top up to 100 just before the ride in order to reduce battery stress.

 

[N0bodyOfTheGoat]

It's going to do nothing as regards making the battery last longer, but I may as well post this other tweak I have with pondering for a while on the Bolt...

Taking the 4iiii Precision 2.0 105 off my road bike and putting it on the Bolt, that has a GRX crankset.

Originally my intention was to mix some road bike rides into the outdoor season (Apr-Nov) with the ebike, but it hasn't happened, mainly because I felt I'd lost a ton of fitness through April and May after two ~3 week respiratory infections. So the road bike has been on the turbo all summer, as an alternative for bad days and very hot days, when getting out has been as good as impossible.

Providing the 4iiii clears the left chain stay, it would give me some real power data for my efforts, rather than looking at Strava's estimated power and then typically taking the turbo 250W assist off the value.

As and when I actually ever get around to trying any of the tweaks mentioned in this thread, which may be some time because I'm not someone who enjoys needlessly playing with bikes, I'll report back.

 

[CXRAndy]

I've just hit 3000 summer miles on my ebike. I use it to go to restaurants/pubs/multi day mini tours in the UK

 

[Drago]

Most modern ebike batteries have a BMS and maintain "headroom." Eg, a full charge in reality will typically be only 83% actual charged.

This is done to a) mainain battery health and b) so as the battery degrades the loss of capacity is taken care of by the headroom so the user does not see any actual degradation in usable capacity for as long as possible.

Don't try and second guess this by putting it through odd charge cycles, onky charging it to an apparent 80%, etc. At best its a waste of time, at worst it can be injurious to the battery.

 

[albion]

It is unlikely that the headroom is that large. Next time I get go a full charge I will check the voltage and calculate.
I think high quality LG batteries squeezed in extra capacity in some smartphones by charging to 4.35V at the cost of much lower cycles.
That might equate to 13% headroom but 4.2V in essentially still considered 'fully charged'. The higher the voltage, the higher the dangers.

On my Samsung tablet I have activated the 'charge to 80%' setting, something many manufacturers do not want you to have.
In fact a few thoughts have it that smartphones overcharge is used to ensure short lifespan, pushing people towards buy a new phone sooner. Manufacturers using 'long smartphone lifespan' to promote sales will likely be the ones who charge to a safer voltage.

 

[ebikeerwidnes]

It is unlikely that the headroom is that large. Next time I get go a full charge I will check the voltage and calculate.
I think high quality LG batteries squeezed in extra capacity in some smartphones by charging to 4.35V at the cost of much lower cycles.
That might equate to 13% headroom but 4.2V in essentially still considered 'fully charged'. The higher the voltage, the higher the dangers.

On my Samsung tablet I have activated the 'charge to 80%' setting, something many manufacturers do not want you to have.
In fact a few thoughts have it that smartphones overcharge is used to ensure short lifespan, pushing people towards buy a new phone sooner. Manufacturers using 'long smartphone lifespan' to promote sales will likely be the ones who charge to a safer voltage.

but you are still not supposed to leave it fully charged for a long time

also - although it is supposed to be better than normal with being left "on charge" for long periods of time it is best to switch it off when it has reached full charge
I have noticed that the charger is warm while charging but is cool 30 minutes after reaching full charge

I have just ordered myself a timer for this - we now have a proper shed outside and I now charge the battery out there - hence it is out fo sight/mind and I keep forgetting it
the timer will allow me to set it to charge for the right amount of time and then stop and not stay with power to the charger for longer than necessary

 

[albion]

On mine, if I charge to 40V instead of 42V then it would be considered 73% charged, 43V being 110%

 

[IanSmithCSE]

Good morning,

If you get 4 legs Ian, charging to 80% and doing 2 legs per charge will massively protect the battery. I always charge mine to 100, needing 100 for flexibility on leisure rides. But I charge to about 80 then top up to 100 just before the ride in order to reduce battery stress.

I see the argument about protecting the battery a lot, but it is not one that I buy into. I still haven't quite reached the stage of needing an ebike, it was an experiment to see what difference one would make so I would rather ride it according to its quoted spec and bitch about those specs being imaginative.

A 250Wh battery pack is quite low capacity, following the more general guidance of charge to 80% and don't discharge below 20% means a reduction in capacity by 40% down to150Wh. Even cheap and chearful TV shopping channel ebikes don't go that low.

I get that battery range and life span is the marketer's 0-60mph equivalent, but if I am anywhere near typical then the claims are getting out of hand.

Most modern ebike batteries have a BMS and maintain "headroom." Eg, a full charge in reality will typically be only 83% actual charged..................

Don't forget that the x35 has a pretty low capacity battery pack, quoted 248Wh, which is made up of 20 18650 cells whose capacity is pretty public, so there is limited room to report not fully charged as fully charged.

With a power indicator that is say 5 bars anything is easy, but the x35 app reports voltage, which is something that I would expect to be fairly accurate. It could be "adjusted" in a VW Testing sort of way.

The app may of couse be being "flexible" but the reported voltage shown below seem to sugges that not much is being left unused.

Depending upon the weather I have seen the minimal assist protection mode kick in with a quoted 40Wh (16% of capacity) remaining, obviously these numbers are all guides but it does indicate how little room there is to spare.

Ian

 

[ebikeerwidnes]

It is not generally very "up front" in the specs and stuff

but I have seen reports that some of the more responsible manufacturers make the charging controllers work so that they never totally max the charge out to protect the battery and make it last as long as possible

the cheaper ones use cheap cells and allow them to charge to the max so the get the headline range figures and the "sales NOW"
but the other want to protect their reputation and long term sales

maybe
we are talking about big companies so you can never be sure about the backgroud policies

but my Bosch system has lasted and worked a lot better than the other ebikes I have had for a long time (Powacycle and Carrera - although who actually makes the Carrera battery and stuff I do not know!)