Another battery question-please can you help?

[Deleted member 4366]

From what I''ve heard on ES, the Bionx battery is not particularly good. It has a sophisticated management system and unsophisticated sony cells.

This guy didn't have a lot of luck with his.
My Bionx-A123 mod | V is for Voltage electric vehicle forum

Here's some more details of what's inside and how it works.
Endless-sphere.com • View topic - BionX hack: non-proprietary battery!

 

[flecc]

Ignore the facts of actual experience and testing if you wish Alex, but the facts are that most mainstream batteries are rated for capacity at the lowest possible usage level. To realise them in practical circumstances means a small frame rider at lowish speeds in still air using the minimum possible power on level ground. In other words, it's the same as e-bike claimed range figures and car mpg figures.

The Peukert effect is an established scientific fact, the higher the rate of discharge from any battery, the lower the capacity made available, and e-bikes are high drain applications. The best manufacturers often correctly rate their batteries for the application, not the optimum lab conditions to suit the marketing department which the majority do.

I'm satisfied that the largest BionX battery is rated the realistic way from the results, and that could give it a 43% higher capacity if it was rated the cynical marketing way that most are. But as Dave says above, the sophisticated system management also plays a part.

And contrary to you, I'm sure from the results that the Kalkhoff BMZ batteries are somewhat overrated for capacity, and direct comparison with the Panasonic ones for the same crank motor units seems to show that to be true, as do the figures you quote for them.

That 25 miles for 540 Wh represents 21.6 Ah per mile, and the Panasonic and similar crank power units simply don't use power at that rate, not even with generous use of the high power mode. Typically Panasonic users return about 12 Wh per mile and the best get 8 Wh per mile, and I doubt this would be very much different for the Impulse units.

My conclusion is that the 540 Wh is an optimistic figure.
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[mountainsport]

Unfortunately your logic isn''t correct. They made other changes to the bike, which have pushed the price up: The Strada has Acera gears with 11T top, which probably means cassette gears, which then means a different motor - probably the same Dapu motor as the BH E-Motion Neo; brakes are a higher spec; forks are hydraulic; and there's probably other changes.

Overall, it looks like a good solution for a high speed decent range bike as long as it has the Dapu motor or equivalent.

You maybe totally correct on that d8veh, but I know for sure that it is an 8fun motor which is used to drive the bike

MS.

 

[Deleted member 4366]

You maybe totally correct on that d8veh, but I know for sure that it is an 8fun motor which is used to drive the bike

MS.

How do you know that? The one in the photo looks too small for a CST, which is the only 8Fun motor with a cassette spline. My logic could be wrong because it's only 7 speed, so could be a free-wheel, but then if it's an SWX, it wouldn't be particularly powerful. Tell us what you know, then it might make sense.

 

[mountainsport]

How do you know that? The one in the photo looks too small for a CST, which is the only 8Fun motor with a cassette spline. My logic could be wrong because it's only 7 speed, so could be a free-wheel, but then if it's an SWX, it wouldn't be particularly powerful. Tell us what you know, then it might make sense.

Hi d8veh the way in which I can make more sense of this is because it is clearly written on my motor.
I am not guessing or basing this by what is on the sites photo.

MS.

 

[Deleted member 4366]

Yes, but the Strada might use a different motor. Can yours do 25mph?

 

[mountainsport]

Yes, but the Strada might use a different motor. Can yours do 25mph?

Whatever a 500 watt does with a 21amp controller.

MS.

 

[Deleted member 4366]

I'm getting confused now. It says in the advert that yours is a 250w motor.

 

[mountainsport]

Just checked it is actually a 25amp controller, I thought that you already had known it was a 500watt motor I used.
About a year ago I had put it up for sale on here. Now, has that answer prevented you from getting anymore confused ?

So, what is the point that you are getting at, now that all has been cleared up or not?

MS.

 

[103Alex1]

Ignore the facts of actual experience and testing if you wish Alex, but the facts are that most mainstream batteries are rated for capacity at the lowest possible usage level..

I'm not ignoring the facts of actual experience, flecc - I'm going by what you cited was actual experience and my own actual experience with a BMS battery... and a BMZ one.

The Peukert effect is an established scientific fact, the higher the rate of discharge from any battery, the lower the capacity made available, and e-bikes are high drain applications. The best manufacturers often correctly rate their batteries for the application, not the optimum lab conditions to suit the marketing department which the majority do.

Well, contrary to what's implied on the BMS battery as 15A continuous rated it is quite capable of coping with max/min amp draws of around 29-33A throughout a ride run at 36V nominal and I've given my measured experiences off Cycle Analyst. If I was running over 48V system or wanting to draw 100A I likely wouldn't be running Li-Ion like the BionX, BMS or BMZ batteries.

That 25 miles for 540 Wh represents 21.6 Ah per mile, and the Panasonic and similar crank power units simply don't use power at that rate, not even with generous use of the high power mode. Typically Panasonic users return about 12 Wh per mile and the best get 8 Wh per mile, and I doubt this would be very much different for the Impulse units.

What about when using the Panasonic units running in derestricted mode at highest possible speeds ? Those figures I quoted are using Impulse system not Panasonic and running at speeds of up to 25mph tuned for high assist, which it is more than happy to do. There's a battery power draw bar on the display which clearly shows when you're pulling high power and if you run the bike at 23-25mph in high gear it'll be pulling over 75% of max available pretty much constantly. So I wouldn't be at all surprised if the motor was consuming that much power. The motor is capable of some very impressive assistance in that mode - but I bet it's not that much more efficient than running a 500W rated hub motor at close to constant top speed. Try running a Bosch with a tuning dongle at 25mph+ or as much as it'll give you up some hills with the available gearing on max power assist and I'll bet it would struggle to deliver 25 miles with one of their 400Wh batteries. We already know the BionX can only manage 18 miles. Perhaps Martin can tell us !

 

[103Alex1]

Alex when you say peak output what do you mean, the size of the motor or by working out peak output through calculation?

MS

By calculation - if you have a 25A controller and a battery that's 36V nominal for example it would be 42 x 25 (42V when fully charged multiplied by 25 amps) = 1.05KW or 900W when at its nominal capacity.

My guess is that if you have a 25A controller your bike will be quite capable of delivering a peak output of over a kilowatt, whatever its nominal rating.

It's all to do with the c rating Alex.

For example - my lipo pack is 12ah and rated @ 25c - I can draw 100amps from it constantly and I will get the full 12ah from it. However try pulling 100amps from a 10ah Ping and you'll be lucky to get 5ah out of it. Nearly all chinese generic batteries are rated @ 1c. Most motor/controller combinations draw at a higher rate than 1c.

The Bionix batteries have a high c rating and they rate their batteries at something like 5c (i.e. 50amps draw on a 9.6ah battery). If you draw at something like 1c (i.e 9.6amps) then you could well pull somewhere in the region of 13/14ah out of it.

OK that makes more sense. So you might get about 11Ah drawing 25A-30A for example ? If so not quite so bad but I can tell from measured Ah consumed on my CST that this capacity would be completely used by a round trip of 10 miles each way with some steep hills and using full power.

Very close to the 18 mile range flecc quoted... so that would mean a BionX £1,050 battery fitted to my converted bike wouldn't give me even 2/3 of the range I'm already getting off a £200 BMS battery which will deliver enough amps to allow the motor to perform to its full capabilities throughout the ride. On that simple comparison I can only conclude paying 5 times as much would be a bit daft and not good value in any way. More importantly the range is way too short for a performance eBike you want to use for performance. Strikes me only LifeCycle have the right idea at the moment !

 

[flecc]

I didn't know you were speaking of a speed boosted system Alex and of course I agree that the consumptions are very high when systems are driven hard.

However, let me get back to that question we started with and which is disputed, the true usable capacity of the BionX battery, and of yours since that's been raised and disputed by me.

Both batteries are made by BMZ using similar oriental cells in series parallel formations, both using 10 cells series banks for the 37 volts. Cells makes they commonly use are from Samsung, Sony and Panasonic.

The Kalkhoff version uses 5 of those banks in parallel to get the capacity which is nominally 15 Ah.

The slightly larger volume BionX battery uses 6 of those in parallel to get the nominal capacity of 9.6 Ah.

So why the big capacity discrepancy? Well,the Kalkhoff one is a Kalhoff claim and I have their document stating about your battery that "We calculate the energy density", giving the result as 15 Ah. It's based on the supplying cell manufacturer's nominal figure of 3 Ah per cell, regardless of application.

The BionX figure is the application one for the BionX motors and comes from BMZ who have designed and made all BionX batteries from the early days of NiMh onwards. It equates to a cell capacity claim of only 1.6 Ah each, which is very low these days.

In other words, if BionX instead of using the BMZ design figure for their system calculated the cell capacity as 3 Ah each like Kalkhoff, the result would be 37 volts 18Ah for a total of 666 Wh*, rather different from their very conservative figures of 36 volts 9.6Ah and 346 Wh.

You know the old comment, "You say tomayto, I say tomarto", but it's the same thing in the end.

*Of course it could be fear of the devil that's keeps them honest about the true capacity!
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[103Alex1]

^^ I guess someone would need to open up a Kalkhoff battery and a BionX battery and prove the cell capacity which would then give comparable results. You may get a better deal than implied in the BionX case for the reasons cited but the main underlying point about inadequacy of capacity is most relevantly illustrated by the real life experience you cited. It's experiential performance I'm going on. I personally feel the Kalkhoff battery is about 1/2 what I'd want from a single battery and the BionX one would likely be no better. Both are astronomically overpriced for the output they deliver.

The BMS battery is incredibly good value and has proven very capable under test over 500 'flat-out' miles. The weather may have had a bit to do with it but I think it's extremely telling that I've done more miles on my DIY bike with big battery and motor in 6 weeks in a very hilly area than I did on my Kalkhoff in 6 months in a considerably less hilly area. Most of that's down to performance capabilities and for that batteries are critical. If I'd had 40Ah I'm pretty sure that 500 miles would have been 750-1,000.

Your inclusion of 350W and 500W BionX versions is what made me assume that we were talking about derestricted bike capabilities rather than ones where the speed limits cap the feasible battery usage and exaggerate the potential for performance overstatement.

Without spelling it out I've been trying to indicate I'm talking about using bikes to their full potential rather than in the context of artificially restricted parameters which mask a great deal of what's actually lying 'beneath the bonnet' (or isn't !), so to speak.

Manufacturers like BionX supplying high power rated bikes but sticking to the same limited capacity batteries are all just stuck in the same 'space'. The Kalkhoff S-Pedelecs are another example ... way too little battery for the bike capabilities. 1,000 - 1,200+ useable Wh and you've got yourself a proper 36V bike you can really use for proper rides of a decent day out. I bet having to cart spare batteries around (aside from being risky) isn't something many people would want to have to do given a choice.

 

[flecc]

I agree on the high prices of course Alex, there's no doubt the low price direct ones like BMS are the best value for the consumer.

I don't think the demand for high capacity is anything like as common as you feel. For at least some enthusiasts maybe, but across the whole e-bike market even the modest 260 Wh of the 26 volt 10 Ah Panasonic system has proved more than adequate for most owners. In fact that replaced the 156 Wh of the 24 volt 6.5 Ah NiMh on the first unit giving 20 miles for most users and up to 24 miles for some.

As ever, we must be wary of judging from this forum's 7000 members of whom only a few are enthusiasts. There's at least 120,000 e-bikes out there used by most owners for very modest purposes like local shopping, short commutes and local social purposes. I bet the majority of them view a 20 mile journey as being long. These same factors are also true of The Netherlands, the largest western e-bike market of them all.

I actually greatly prefer the multi-battery option for long range journeys, it means I only cart around the weight I need on the majority of shorter journeys.
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[Deleted member 4366]

Just checked it is actually a 25amp controller, I thought that you already had known it was a 500watt motor I used.
About a year ago I had put it up for sale on here. Now, has that answer prevented you from getting anymore confused ?

So, what is the point that you are getting at, now that all has been cleared up or not?

MS.

Yes I am confused because the question is what motor is in the Strada.

 

[mountainsport]

Yes I am confused because the question is what motor is in the Strada.

Hi d8veh,

All that I have been mentioning from day one is about the pricing of these batteries, and some how the motor from the Strada seemed to have gradually find it's way into the equation, i'm not really interested in the motor at this point in time. Let's move on from this because there is so much more to learn from you about ebikes

MS.

 

[mountainsport]

Sorry Alex I just had seen your answer to my question, cheers for that. Basically my 500w motor is capable of the power being doubled. Out of interest how can this extra power be achieved according to my setup?

MS.

 

[103Alex1]

The BionX figure is the application one for the BionX motors and comes from BMZ who have designed and made all BionX batteries from the early days of NiMh onwards. It equates to a cell capacity claim of only 1.6 Ah each, which is very low these days.

Just thought about the similarity with 18650 Ultrafire vs Sanyo type battery debates (!) .... The 18 full power range you quoted really is very low especially for a bike with regen. Does make me think that perhaps the base cells aren't actually as good as in some other batteries (or perhaps quality is variable) and the manufacturer is opting to cover themselves for this.

The experiential range does suggest no more than an 11-12Ah useful capacity. Probably less if regen was deployed.

BionX aren't likely to undersell themselves unless there's a reason and if their bikes aren't drawing very high amps there's even less reason. Something still doesn't quite add up !

Only thing I can think of otherwise if Kalkhoff BMZ batteries are that overstated is that the crank drive Impulse is so much more efficient than a BionX hub motor it can easily accommodate 25 mile range flat out at full power in Sport configuration riding at top speed (22-25mph) in derestricted mode and still likely won't actually hit low voltage cutoff in less than 30 miles - even if the last 5 or so cost a couple of mph. So you're definitely getting about 50% more miles which is coincidentally notionally what the 9.5 versus 15Ah stated capacities would lead a lay person to expect.

I don't think the demand for high capacity is anything like as common as you feel. For at least some enthusiasts maybe, but across the whole e-bike market even the modest 260 Wh of the 26 volt 10 Ah Panasonic system has proved more than adequate for most owners. In fact that replaced the 156 Wh of the 24 volt 6.5 Ah NiMh on the first unit giving 20 miles for most users and up to 24 miles for some.

...

I actually greatly prefer the multi-battery option for long range journeys, it means I only cart around the weight I need on the majority of shorter journeys.
.

Perhaps but I think European markets are the wrong indicator for higher rated bikes such as 500W nominal ones - the American market is probably a better indicator because they're legal in many states there. People riding restricted 250W rated bikes aren't likely to be pushing for much more than 18-24Ah. However for derestricted bikes and higher rated ones run with higher amp controllers I'll bet that consumer appetite for bigger batteries is much greater than supply would indicate. I bet plenty of people who buy a 500W bike want to ride it at higher speeds. If they don't it's most likely because they can't without running out of juice well before they want to.

It's therefore even more surprising to me that BionX haven't moved on considerably more than their European counterparts in going for higher capacity batteries.

Have to admit an extra couple of kg makes very little difference to me when you're talking about a derestricted bike or a 500W hub one so bigger battery weight doesn't really affect performance at all. Having to cart around a second one takes up space and needs secure packing to stop it getting knocked about especially on bumpier ground and very much so at higher speeds. Perhaps it's just that in US many higher powered bikes are running LiPos already instead ?

Lithium Electric Bike batteries (Lifepo4, and LiPo)

Sorry Alex I just had seen your answer to my question, cheers for that. Basically my 500w motor is capable of the power being doubled. Out of interest how can this extra power be achieved according to my setup?

MS.

I don't know how the lifecycle bikes work, MS. My guess is that if you have an off-road button this unlocks the power by derestricting the bike. The motor's capabilities are fixed. It is the controller which regulates the max amps (current) the battery can feed it and the battery which determines for how long at that rate.

Therefore if you have a 37V battery on your bike and the motor is a 500W nominal motor the limiting factor is the 25A controller. If you can already unlock that without a speed cutoff you're getting as much as your system is capable of giving without changing one of the components. In very basic terms, if I understand it right (no doubt I'll be corrected if not !) you can either increase the battery voltage by fitting a supplementary pack (or getting a higher voltage one like a 48V) or else swap the controller for one which will run at higher amps. Either approach would likely increase speed.

You'd really need to supply details of the exact motor fitted though, because running motors at higher amps than they are designed to handle can easily lead to them burning out. So whilst I think from your questions you're exploring things from a battery angle, when you get on to talking about realizing performance from the bike the battery capacity is only really about how far you can go.

Adding a few mph to your assisted speed can shave a considerable amount off how far you can go on your battery. What really matters most is what motor is fitted and you can start to work out from that how hard you can push it without it falling over. I may be wrong but think that's what d8veh is basically starting to lead you towards getting to grips with .

 

[flecc]

You're really trying hard Alex, but it doesn't wash, what you've said about the BionX battery is pure conjecture with no evidence in support. The 18 miles quoted was for a derestricted 350 watt unit deliberately run at the highest output level 4 power in mixed territory. Users run the same 350 watt system in a normal manner quoting ranges well over 30 miles, so you shouldn't infer too much from the worst case lowest figure. After all you quoted 25 miles for your nominally 15 Ah battery on a 250 watt derestricted unit, so that is commensurate with the BionX 350 watt unit which in any case will outperform yours for speed on hills with both in highest power mode, given exactly equal rider inputs. In another comparison, even the 250 watt Panasonic system with the 10Ah battery has had 18 miles quoted in here by more than one user for range when it's geared up to enable assist to 20 mph, and that's not even using high power mode all the time. Your conclusion of more range from yours due to greater efficiency is therefore fallacious, and the BionX system has always been highly regarded for it's sophistication and efficiency.

As for guessing the BionX cells are possibly lower quality, that is being ridiculous. The two batteries are by the same German quality manufacturer and BionX are not price sensitive in the way that Derby Cycles are likely to be. It's the latter's battery that you can find heavily discounted on e-bay, not the BionX one. The simple fact is that the BionX, not being price sensitive, uses 20% more cells to do the same job and is realistically rated for application capacity. Yours is rated by the cell manufacturer capacities of 3 Ah, 5 series banks in parallel of 3000mAh cells being your nominal 15 Ah. That is undeniable. Kalkhoff also supply a visually identical content 11Ah battery, the capacity figure derived from the use of 2250mAh cells instead, five of those being 11.25Ah. Those cell makers figures are always best case for the general market and don't apply to any specific application.

As for the capacity the market wants, your own comments support what I'm saying. In the USA and Canada where the BionX units are not restricted and are popular big sellers, there doesn't appear to be a big demand for larger batteries for them, and in Europe on the 250 watt units they fit even smaller batteries. I repeat, that suits the main e-bike market, it's mostly a tiny enthusiast market that seems to ask for very large capacities. Across the bulk of the e-bike market users mostly do very modest trip lengths, logical since they are bought in the main as utility bikes rather than for enthusiast/sporting/long journey purposes. Even in this enthusiast forum there's been some members who've built half size batteries to fit their modest range needs, avoiding carrying around excess weight. That was at one time especially popular when the heavier NiMh batteries were more common on e-bikes.

An approach to suit all is that of eZee Kinetic, offering a wide range of batteries, 37 and 48 volts, capacities from 8Ah to 20Ah, in-frame, carrier or bottle, but they are alone in that, showing how small the market demand is for that large choice.
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[103Alex1]

You're really trying hard Alex, but it doesn't wash, what you've said about the BionX battery is pure conjecture with no evidence in support. The 18 miles quoted was for a derestricted 350 watt unit deliberately run at the highest output level 4 power in mixed territory. Users run the same 350 watt system in a normal manner quoting ranges well over 30 miles, so you shouldn't infer too much from the worst case lowest figure. After all you quoted 25 miles for your nominally 15 Ah battery on a 250 watt derestricted unit, so that is commensurate with the BionX 350 watt unit which in any case will outperform yours for speed on hills with both in highest power mode, given exactly equal rider inputs. In another comparison, even the 250 watt Panasonic system with the 10Ah battery has had 18 miles quoted in here by more than one user for range when it's geared up to enable assist to 20 mph, and that's not even using high power mode all the time. Your conclusion of more range from yours due to greater efficiency is therefore fallacious, and the BionX system has always been highly regarded for it's sophistication and efficiency.

As for guessing the BionX cells are possibly lower quality, that is being ridiculous. The two batteries are by the same German quality manufacturer and BionX are not price sensitive in the way that Derby Cycles are likely to be. It's the latter's battery that you can find heavily discounted on e-bay, not the BionX one. The simple fact is that the BionX, not being price sensitive, uses 20% more cells to do the same job and is realistically rated for application capacity. Yours is rated by the cell manufacturer capacities of 3 Ah, 5 series banks in parallel of 3000mAh cells being your nominal 15 Ah. That is undeniable. Kalkhoff also supply a visually identical content 11Ah battery, the capacity figure derived from the use of 2250mAh cells instead, five of those being 11.25Ah. Those cell makers figures are always best case for the general market and don't apply to any specific application.

As for the capacity the market wants, your own comments support what I'm saying. In the USA and Canada where the BionX units are not restricted and are popular big sellers, there doesn't appear to be a big demand for larger batteries for them, and in Europe on the 250 watt units they fit even smaller batteries. I repeat, that suits the main e-bike market, it's mostly a tiny enthusiast market that seems to ask for very large capacities. Across the bulk of the e-bike market users mostly do very modest trip lengths, logical since they are bought in the main as utility bikes rather than for enthusiast/sporting/long journey purposes. Even in this enthusiast forum there's been some members who've built half size batteries to fit their modest range needs, avoiding carrying around excess weight. That was at one time especially popular when the heavier NiMh batteries were more common on e-bikes.

An approach to suit all is that of eZee Kinetic, offering a wide range of batteries, 37 and 48 volts, capacities from 8Ah to 20Ah, in-frame, carrier or bottle, but they are alone in that, showing how narrow the market demand is for that large choice.
.

God, keep your knickers on flecc. I'm simply pointing out with some conjecture that there are a whole host of things which might be inputting to some greater or lesser extent and making the point that no manufactururer's claims (or test results) can be taken too seriously.

From what you've said we've numerous examples of 18 mile ranges off 9,5-10Ah batteries (Panasonic and BionX) used with full power in their respective systems when run to potential and a 25-30mile range off a 15Ah Kalkhoff battery in its installed system used the same way. So whatever the manufacturers' claims are based on as to stated Ah, 'c' ratings etc etc there is a broadly commensurate realized uplift in realized range using bikes in top power modes comparing the 10Ah with the 15Ah installations. Purely coincidence becuase your analysis of marketing material proves there must be foul play afoot ? If so then it is a happy one. Because in the end as a user all I am interested in is realized output.

BionX is a hub motor & Impulse is a crank drive. We're often given the imjpression that crank drives like Bosch/Impulse/Panasonic are more efficient than hub motor systems, no ? I haven't tried a 350W gearless hub motor so I don't know what it's like on hills set against a crank drive motor. Getting a feeling that nominally 350W vs 250W motors don't mean much given the way the tests are performed and the controller settings can render the same motors capable of being rated as either depending on how they are configured especially in that range.

The truth seems to be that no-one knows what exact cells are used in BionX batteries - or Kalkhoff/Bosch ones and I don't believe anything manufacturer tests say because they can test based on one production component and then vary production specification.

As far as battery size is concerned when the differentials are large in terms of price I am not surprised people try to buy the smallest they think they can manage with. With lower powered bikes weight matters more and LiFePo4 batteries often used in US bikes were already heavier to begin with. Building half-size battery packs to save weight makes sense if you want to ride at lower assist levels or are using less powerful motors. That's not what where I'm coming from here ! What is far more likely is that expectations are set by the manufacturers in terms of exaggeration (and price) and people follow. It's only once you experience for yourself what you can really have / use that people who have not been keen cyclists all their lives moving to assisted cycling on account of age/health problems or not in it to lose weight wake up to what's "missing" in the supplier equation. The e-zee example includes Chinese 20Ah batteries as a max - which by your own implications are presumably likely not really 20Ah if run at higher amps but more like a BionX 9,5Ah ? Neither is particularly large ... the e-zee 500W US/Canada bikes are run with 22A controllers too if I'm not mistaken ? This will limit power consumption.... and performance !

Basically, I appreciate that big batteries and high speeds are not for you, flecc and that suppliers are taking a long time to come round to releasing bikes with higher norms or capacity and performance where there's a market for them. But please don't imply that this is necessarily reflective of a lack of customer appetite. In Europe it's down to speed restrictions and in US it's likely down to price. Plus the over-riding push to keep people viewing eBikes as bicycles to be used with a bit of assistance rather than allowing them to occupy a space as machines with their own objective capabilities, suitably equipped. And the effects of that political agenda are written all over the market.

Lifecycle seem to be moving in to trade on the battery capacity advantage on bikes with off-road boost - good on them, but I personally think their prices are too high for what they are supplying in hub motor space. It would be nice to see a few more suppliers follow their lead.