Making an ebike more efficient for road rides

[N0bodyOfTheGoat]

I was hoping there might be some sort of general ebike Q&A thread where I could include this, but I can't see one.

My GT eGrade Bolt ebike is quite light for an ebike at just over 15Kg before I attach 1/2 ~700ml bidons, but that comes at the cost of a relatively small 248Wh battery, so I'm looking at ways to tweak the ebike to get to the motor cutoff 15.5mph quicker on the flat/downhill, thereby increasing the battery range to ~60 miles with ~4000 feet climbing while using ~75/140/250W assist levels.

Swap out the 35/40mm Marathon Supremes for 30/32mm GP5000s I already own, bit lighter; less rolling resistance; bit quicker for my effort and motor assist effort?
Swap out the butyl tubes for either some latex tubes I already own, or have my first dabble into TPU tubes, reducing rolling resistance a little more?
Put the front GP5000 on my Hunt Aero Light Disc front wheel; bit lighter; bit more aero; or do I fit my front VEL 50RL 50mm carbon rim?

While I expect the front wheel; tyre; tube swaps will help a bit, I'm just not sure how much it will help given I'm averaging ~16mph on rides when I'm feeling good and doing threshold efforts up the ~270+ foot climbs while using turbo assist.

I've had a pair of clip on TT bars in the spares box for a few years, but I've not used any for ~25 years, so I'd be very selective of where I'd use them and I'm ~8 months into dealing with a frozen shoulder that prevents me from tucking my left elbow as close to my centre by a good ~5cm compared to my right arm. I'm not sure this is a good option, even though it has potential benefits!

This is all moving into territory beyond what I expected after only owning an ebike for a few months, I used to do monthly 100Km rides until my long covid and my longest ride on the Bolt so far is one ~50 miles with 3225 feet climbing the other weekend that used ~81% of the battery. Besides the battery, I'm struggling with multi hour saddle comfort (may have just solved this by swapping to my Selle SMP Extra) and the unknown of how my body will cope with more than 3hrs10mins of riding.

Anyone been through anything similar tweaking their ebike setup?

 

[Drago]

What you're seeking is some kind of automatic dynamic system that lowers the eleftric motor cut off when the terrain should favour jt? Nice idea.

 

[fossyant]

Decent tyres will certainly lower the rolling resistance, and increase battery life.

 

[N0bodyOfTheGoat]

Whatever speed https://www.bicyclerollingresistance.com/ tests at suggests a ~20W saving from the tyre and tube swap.

The Marathon Supremes aren't super slow, feel much better than the knobbly Nanos supplied with the ebike, but it's the question of is the effort of swapping things out worth the battery gains and a little more speed when it's just me pedalling at approx 16-42mph (averaging ~16.5mph on a good day).

I haven't weighed the supplied gravel front wheel, but it feels like it could easily be twice the weight of my Hunt and VEL front wheels, that are ~750g each.
The only slight hassle would be tweaking the caliper alignment for a different front wheel.

The other tweaks I forgot to write about earlier were switching to a more normal for me 110mm stem, rather than the more agile 90mm supplied and possibly lowering the bars a bit using my Deda adjustable (which then keeps the carbon fork steerer happy by not moving spacers above stem).

Most of this faff is all in the name of trying to recreate a ride similar to my last hill climb effort on Queen Liz's funeral day on my normal road bike before I got covid that became long covid, ~4 miles from Sheet (just east of Petersfield) to Warren Corner as part of a ~53 miles 2600 feet ride.

 

[fossyant]

Marathon Supremes are a slow tyre. Personally any road tyre will be quicker - Vittoria Zaffiro or Rubino are much cheaper than GP5000's and roll very well. I wouldn't bother with TPU or latex tubes TBH - just more faff. Vittoria Ultralight butyl tubes are excellent, as are Decathlon's own - you are chasing marginal gains at this point.

 

[Dadam]

I fit Rubino Pro 28s (measure 30 on the rim) to my Gain and it feels great to ride even with motor off. Did a couple of 60 mile rides and used only around 22% of the battery.

Something specific to eBike though that Bosch rexommend and I follow is to use that higher gear when your cruising as well, it's something to do with turning the motor faster but with less resistance improves the battery life.

That advice is for Bosch bikes with mid motors. OP's bike is Mahle X35 system hub motor and the gear the bike is in makes zero difference to the motor, only how the pedalling feels to you. The motor itself is in effect a single speed. I read that its internal gearing is optimised to roughly 12mph, which feels about right.

 

[All uphill]

How about getting the battery to the optimum temperature while charging so you can squeeze a few more electrons in?

I understand that can make a big difference on cold days.

 

[ColinJ]

Why not just turn the motor assist off for the flat roads and downhills, saving it for the climbs? It sounds like you can manage 16+ mph without help, and that is faster than I usually average!

 

[N0bodyOfTheGoat]

How about getting the battery to the optimum temperature while charging so you can squeeze a few more electrons in?

I understand that can make a big difference on cold days.

I've no idea what the optimal charging temperature is, but the ebike lives indoors, during summer the flat is usually 21-30C, more like 16-18C in winter, good point though.

Put on charge at least 30mins after ride end, usually charged to 80% unless I'm determined to do an ebike ride next day at latest, given at least 30mins after disconnecting charger until heading out.

 

[albion]

All your gains are marginal with comfort possibly being lost. The 20 watt saving might be far less at pedestrian body safe speeds.
I cut my distances down so that I could cope better with a daily ride. The effect of that is that I have sought out many new local near traffic free routes and flatter too.

It is quite a voyage of discovery now, and with flatter routes, my ride distance has hardly decreased at all. You certainly need to do the same, enough to question even needing the ebike. I now ride at power level zero a lot but appreciate the battery when needed.

 

[N0bodyOfTheGoat]

Why not just turn the motor assist off for the flat roads and downhills, saving it for the climbs? It sounds like you can manage 16+ mph without help, and that is faster than I usually average!

Turning the assist off or simply not pedalling downhill when I'm travelling under 15.5mph is something I do employ already on some ebike rides, but turning off assist on the flat on a long ride is a fine balancing act, because my stamina is so poor and has been for almost three years of long covid. On a few recent short rides I've unusally had a ~10mph north easterly headwind and I've needed mid 140W assist to even threaten 15mph on the flat.

Averaging ~16mph is only something I can get near on my good days, when I'm really pushing myself up climbs while getting max turbo assist and then using the combined weight ~112Kg of the ebike and me on the descents to really boost my average up. Averaging higher than the 15.5mph motor assistance cutoff is only a very recent thing on very good days, since the 50-miler two weekends ago (I've only done 9 rides over 30 miles in last 18 months, the one on my normal road bike left me exhausted for days) it's not happened and it was only just that day...

That was turbo 250W for 3.5 hill efforts plus a few short steep ramps (maybe ~25mins motor time, which would have been ~40% of total battery consumption), only ~2mins motor time of 140W and the rest was in eco mode 75W (but who knows how much was active motor assist time, ~1hr40mins?).

It does all seem a bit marginal gains, but part of me is curious about the tweaks, while another part of me thinks can I be bothered with fiddling with the bike for I expect well over an hour!

 

[albion]

I do the gentle hills in bottom level 1, of 5. Same for a headwind, though I am lucky to get past 10mph there. Level 3 would get me to 15mph but I am in no hurry, only using strong assist when really needed (10% + hills)
Keeping speed low can easily add 100%+ battery range.

 

[Dogtrousers]

I don't know anything about e-bikes but 16mph (nearly 26 km/h) strikes me as awfully fast. If you were to reduce that I'd imagine you'd improve efficiency.

I say "I imagine" because it's nothing more than a wild guess/ gut feel. I think you are wasting more energy fighting air resistance at that speed than you would be at a more sedate speed.

If I'm right (and I rarely am) slowing down a bit may eke out more distance, but at the risk of running into your personal time-in-the-saddle limits.

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.

 

[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.