Halford's ebikes

[Bonzo Banana]

For more range, if the controller allows it, slow down.

In the wake of Mike Burrows' sad passing, I rushed to my local online auction site and bought a copy of his excellent 'Bicycle Design' book. He points out that at normal riding speed, aerodynamic losses account for 90% or more of energy input for an upright riding stance. Aero losses are proportional to the square of speed, so range can be stretched a fair bit with a minor speed reduction.

24Wh per mile... ouch!

Such a brilliant man and very sad to hear. The worst cycling news I'd seen since the sad passing of Sheldon Brown. I don't have that book myself but I used to go into the Dorchester library when I had some time to spare and read a few bike books and I've never seen a tattier library book than Mike Burrow's Bicycle Design book. The pages were falling out and it must have been read by 100s of people. It was a reference book so couldn't be lent.

Still plan to pick up a Giant Halfway at some point. I do have a Giant road bike. It was the cheaper compact frame road bike the OCR for the masses where as was it the TCR I think he designed for professional racing with the same geometry. Mine is the very last model I think with a freewheel as the next version was freehub/cassette based.

 

[flecc]

Presumably that Giant model is in eco mode to do that.

Definitely not. The Eco mode was far too weak to be useful. I never used it in all my years of ownership. 8 or less Wh per mile was the norm for that Giant Lafree with most owners, and as your post shows, ExtraEnergy got 22 miles range in normal mode, 7.1 Wh per mile.

That original Panasonic unit was very sparing in its use of current, assisted by it being torque sensored so the rider had to make their contribution.

The original Torq and Quando in contrast were both cadence sensored and had throttles, the emphasis on performance and their Bafang motor/controller with emphasis on high power. Our survey of the large numbers who owned the Torq or Quando overwhelmingly showed 24 Wh per mile to be their norm. One Quando owner managed only 11 miles range normally, 33Wh per mile!!

In other words I was answering Matthew's specific request, which was:

"It would be interesting to see comparative running costs of mid-drive drive train and relatively gentle battery use vs absolute hammering of battery for powerful hub drives with much lower drive train wear!"

That trio of bikes which I owned simultaneously exactly matched his request. The first was very gentle on its small battery, the latter two were greedy beasts which really hammered the batteries, destroying one battery in just three months in my case, earning a free replacement which failed at ten months.
.

 

[cyclebuddy]

The scheme will give her £2000 in vouchers to spend on ebikes but only a specific shops. The options are quite limited and include Halfords.

What vouchers? What scheme? What other stores participate?

If they include Rutland or Evans or E-bikes Direct (for example) your choice widens considerably... to include the main popular brands like Cube which isn't really Halfords forte, specialising as they do mostly in their own imports/brands.

 

[Bonzo Banana]

Definitely not. The Eco mode was far too weak to be useful. I never used it in all my years of ownership. 8 or less Wh per mile was the norm for that Giant Lafree with most owners, and as your post shows, ExtraEnergy got 22 miles range in normal mode, 7.1 Wh per mile.

That original Panasonic unit was very sparing in its use of current, assisted by it being torque sensored so the rider had to make their contribution.

The original Torq and Quando in contrast were both cadence sensored and had throttles, the emphasis on performance and their Bafang motor/controller with emphasis on high power. Our survey of the large numbers who owned the Torq or Quando overwhelmingly showed 24 Wh per mile to be their norm. One Quando owner managed only 11 miles range normally, 33Wh per mile!!

In other words I was answering Matthew's specific request, which was:

"It would be interesting to see comparative running costs of mid-drive drive train and relatively gentle battery use vs absolute hammering of battery for powerful hub drives with much lower drive train wear!"

That trio of bikes which I owned simultaneously exactly matched his request. The first was very gentle on its small battery, the latter two were greedy beasts which really hammered the batteries, destroying one battery in just three months in my case, earning a free replacement which failed at ten months.
.

It says in the description of the Giant bike that is was NiMH based so presumably didn't have to keep reserve current in the battery it could be fully discharged safely. So that would give it a bit of bonus power possibly.

Also without knowing how much torque assistance it gives in normal mode its hard to make a fair comparison with other bikes. It's quite possible the Subway for example gives more torque output in eco mode.

Any ebike motor system can give it's battery a hard time if the controller takes too much current. Even very weak hub motor ebike systems can give their battery a very hard time if the battery is low capacity without many cells in parallel or using fairly low quality cells. Even if you have a very powerful hub motor you can configure a battery pack that will cope with it easily. There are also parameters you can set in many ebike kits to limit current output of the controller to protect the battery and extend its life.

 

[flecc]

It says in the description of the Giant bike that is was NiMH based so presumably didn't have to keep reserve current in the battery it could be fully discharged safely. So that would give it a bit of bonus power possibly.

Also without knowing how much torque assistance it gives in normal mode its hard to make a fair comparison with other bikes. It's quite possible the Subway for example gives more torque output in eco mode.

Any ebike motor system can give it's battery a hard time if the controller takes too much current. Even very weak hub motor ebike systems can give their battery a very hard time if the battery is low capacity without many cells in parallel or using fairly low quality cells. Even if you have a very powerful hub motor you can configure a battery pack that will cope with it easily. There are also parameters you can set in many ebike kits to limit current output of the controller to protect the battery and extend its life.

All obvious of course, teaching granny to suck eggs! I really don't need such elementary lessons.

As I made clear, the Panasonic units were designed to be very sparing with current, and it's done in a variety of cunning ways:

This Panasonic design has integral to it the gradual phase down of full assist starting at 15 kph (9.4 mph) when the bike is in top gear.

For example, at a speed of 11 mph, 71% of the torque measured riders input is given as motor assistance. At a higher speed of 13 mph, only 36% of rider input is given by the motor and by 15.5 mph the assistance stops of course.

In other words, the unit seeing the rider cycling faster is interpreted as them needing less help.

Being a crank drive unit these speeds are tied to pedal cadence, so as pedalling slows, it's interpreted as the rider needing more help. Therefore the unit only gives full assistance up to a cadence of 40, which is 1.5 seconds per pedal rotation and of course that is the 9.4 mph in top gear.

Changing down reduces the speed at which maximum power is delivered. So for example it's available at only 3.8 mph in the bottom gear of a Nexus 7 hub gear, meaning an average weight and fitness rider inputting 200 watts could climb a 1 in 3.7 (27%) hill.

You are flogging a dead horse with the argument that hub motors are as efficient as mid motors. In any practical circumstance they never are, that is an absolute. Hub motors are used for their convenience and simplicity at the cost of lower efficiency at all times when they are outside their perfect operating zone. Like you I'm a hub motor fan for the benefits of the simplicity and less transmission wear and maintenance, but that means I accept the lower efficiency.
.

 

[Bonzo Banana]

All obvious of course, teaching granny to suck eggs! I really don't need such elementary lessons.

As I made clear, the Panasonic units were designed to be very sparing with current, and it's done in a variety of cunning ways:

This Panasonic design has integral to it the gradual phase down of full assist starting at 15 kph (9.4 mph) when the bike is in top gear.

For example, at a speed of 11 mph, 71% of the torque measured riders input is given as motor assistance. At a higher speed of 13 mph, only 36% of rider input is given by the motor and by 15.5 mph the assistance stops of course.

In other words, the unit seeing the rider cycling faster is interpreted as them needing less help.

Being a crank drive unit these speeds are tied to pedal cadence, so as pedalling slows, it's interpreted as the rider needing more help. Therefore the unit only gives full assistance up to a cadence of 40, which is 1.5 seconds per pedal rotation and of course that is the 9.4 mph in top gear.

Changing down reduces the speed at which maximum power is delivered. So for example it's available at only 3.8 mph in the bottom gear of a Nexus 7 hub gear, meaning an average weight and fitness rider inputting 200 watts could climb a 1 in 3.7 (27%) hill.

You are flogging a dead horse with the argument that hub motors are as efficient as mid motors. In any practical circumstance they never are, that is an absolute. Hub motors are used for their convenience and simplicity at the cost of lower efficiency at all times when they are outside their perfect operating zone. Like you I'm a hub motor fan for the benefits of the simplicity and less transmission wear and maintenance, but that means I accept the lower efficiency.
.

That's quite an abusive tone and I don't remember you mentioning Nimh previously. I certainly don't accept mid-drive as the most efficient. I did quite a lot of research on ebike motor efficiency using expert sites like Grin and there was huge overlap for efficiency and the most efficient motor I came across was a small geared hub motor. However its a mute point as it really depends on your criteria for efficiency, overall use, up hills etc. As I said previously torque based sensor's help limit motor output. I certainly accept mid-drive as the most powerful capable of the most torque in its most powerful models. If you are looking at ebikes with the smallest capacity battery supplied but with reasonable range it has to be a small geared hub motor. You get entry level geared hub motor ebikes with batteries as low as 150Wh that provide reasonable range like 20 miles but again its about the assistance level. Remember the criticism of direct drive hub motors is their maximum efficiency is at higher speeds but a geared hub motor brings that speed right down because of the internal gearing. Surely efficiency really is where the motor is operating at higher efficiency for more of the time for normal use.

A geared hub motor ebike can be a very light ebike, has far less losses inside the motor as the gearing is less complex and has pretty much no losses when freewheeling and has no motor losses through the drivetrain. It's drivetrain can last much longer so it's drivetrain is less likely to be worn and being less efficient. I totally accept that scaling motor power through the gears has efficiency gains but you have to look at the full picture.

Going back to Halfords Carrera Subway with a 317Wh battery and a torque sensor with geared hub motor they claim up to 40 miles. You get significantly less with a cadence sensor and a similar hub motor so part of the gains is the torque sensor.

If you have a ebike that is significantly lighter as many geared hub motor ebikes then the requirement to use the motor is also reduced.

There is so much going on in mid-drive motors, a large number of nylon cogs typically, sometimes a belt and now they have clutch plates to eliminate drag and the bearings are under huge load due to the riders own efforts going through the motor. They are extremely complex and prone to high wear and failure especially if used as an e-mountain bike. If you factor in failure rate to the calculation of efficiency i.e. the need for replacement parts in the drivetrain and repair of the motor itself on a more regular basis and their shorter life as a solution they look far less efficient anyway. Then factor in many are sold on a highly proprietary basis with no access to spares and restricted part compatibility.

I personally think they are junk solution unless you really, really need that additional torque for hill climbing i.e off-road use.

Definition of efficiency

1: the quality or degree of being efficient
2a: efficient operation
b(1): effective operation as measured by a comparison of production with cost (as in energy, time, and money)
(2): the ratio of the useful energy delivered by a dynamic system to the energy supplied to it
3: EFFICIENCY APARTMENT

 

[flecc]

That's quite an abusive tone and I don't remember you mentioning Nimh previously. I certainly don't accept mid-drive as the most efficient. I did quite a lot of research on ebike motor efficiency using expert sites like Grin and there was huge overlap for efficiency and the most efficient motor I came across was a small geared hub motor. However its a mute point as it really depends on your criteria for efficiency, overall use, up hills etc. As I said previously torque based sensor's help limit motor output. I certainly accept mid-drive as the most powerful capable of the most torque in its most powerful models. If you are looking at ebikes with the smallest capacity battery supplied but with reasonable range it has to be a small geared hub motor. You get entry level geared hub motor ebikes with batteries as low as 150Wh that provide reasonable range like 20 miles but again its about the assistance level. Remember the criticism of direct drive hub motors is their maximum efficiency is at higher speeds but a geared hub motor brings that speed right down because of the internal gearing. Surely efficiency really is where the motor is operating at higher efficiency for more of the time for normal use.

A geared hub motor ebike can be a very light ebike, has far less losses inside the motor as the gearing is less complex and has pretty much no losses when freewheeling and has no motor losses through the drivetrain. It's drivetrain can last much longer so it's drivetrain is less likely to be worn and being less efficient. I totally accept that scaling motor power through the gears has efficiency gains but you have to look at the full picture.

Going back to Halfords Carrera Subway with a 317Wh battery and a torque sensor with geared hub motor they claim up to 40 miles. You get significantly less with a cadence sensor and a similar hub motor so part of the gains is the torque sensor.

If you have a ebike that is significantly lighter as many geared hub motor ebikes then the requirement to use the motor is also reduced.

There is so much going on in mid-drive motors, a large number of nylon cogs typically, sometimes a belt and now they have clutch plates to eliminate drag and the bearings are under huge load due to the riders own efforts going through the motor. They are extremely complex and prone to high wear and failure especially if used as an e-mountain bike. If you factor in failure rate to the calculation of efficiency i.e. the need for replacement parts in the drivetrain and repair of the motor itself on a more regular basis and their shorter life as a solution they look far less efficient anyway. Then factor in many are sold on a highly proprietary basis with no access to spares and restricted part compatibility.

I personally think they are junk solution unless you really, really need that additional torque for hill climbing i.e off-road use.

Definition of efficiency

1: the quality or degree of being efficient
2a: efficient operation
b(1): effective operation as measured by a comparison of production with cost (as in energy, time, and money)
(2): the ratio of the useful energy delivered by a dynamic system to the energy supplied to it
3: EFFICIENCY APARTMENT

There's nothing abusive about my first sentence reminding you that others can know a lot more than you about a subject.

I was first fitting assist motors to bicycles in the trade in 1950 and have retained a strong interest in the subject ever since. That is why I was the first member to join this forum long ago, invited to join when it opened because of my existing e-bike help web sites. Now 72 years of accumulated knowledge and experience.

There is so much wrong and confused in your reply that I'm not going to tackle everything point by point since it's clear you have a somewhat closed mind on the subject.

The only measure of efficiency is your number 2 at the foot of your post:

"the ratio of the useful energy delivered by a dynamic system to the energy supplied to it"

All the rest you say to try to justify your position is waffle and often wildly incorrect. For example what large number of nylon cogs in a mid drive? The Panasonic one I described has precision machined steel helical gears. Their later unit uses only a single nylon gear in a single stage reduction, so efficient that they made it a feature of their sales promotion. And its reliability is legendary.

Compare that single stage gear wheel with a typical hub motor with an epicyclic, four gear wheels driving a hub shell toothed rack which is their fifth gear wheel. Some like Suntour and AKM even have stepped cogs for two steps of reduction using a total of nine toothed gear wheels !!

You see, completely the opposite of what you were trying to convince me, showing the flaw in selecting limited examples to do that.

In truth all kinds of e-bike motor have intrinsic inefficiencies. Hub motors with fixed internal reduction gearing don't adequately cover the e-bike motor operating range, ideally needing a choice of two gears. Hence Xionda and SRAM trying to address that.

Mid drives have a different efficiency problem, driving through the large number of gears a rider needs, when the motor, like the hub motor, only really needs two gears. That means they are at the mercy of the rider actually choosing the best gear for the motor all the time.

However, since the mid drive can have the two gears when the rider chooses correctly, it is more efficient than a single stage reduction hub motor across all usage circumstances. That is an absolute of physics.

When the mid drive rider doesn't choose the correct gear, that is rider inefficiency which shouldn't be confused with motor unit efficiencies.
.

 

[matthewslack]

Efficiency is too narrow a focus for most ebike users. More important is that a bike can do the job its rider needs done.

Wh consumed per mile is vital to me as a long distance touring rider, and the ability to climb the steep 'last hill before home' without asking me to work hard is more important when I'm commuting.

 

[Bonzo Banana]

There's nothing abusive about my first sentence reminding you that others can know a lot more than you about a subject.

I was first fitting assist motors to bicycles in the trade in 1950 and have retained a strong interest in the subject ever since. That is why I was the first member to join this forum long ago, invited to join when it opened because of my existing e-bike help web sites. Now 72 years of accumulated knowledge and experience.

There is so much wrong and confused in your reply that I'm not going to tackle everything point by point since it's clear you have a somewhat closed mind on the subject.

The only measure of efficiency is your number 2 at the foot of your post:

"the ratio of the useful energy delivered by a dynamic system to the energy supplied to it"

All the rest you say to try to justify your position is waffle and often wildly incorrect. For example what large number of nylon cogs in a mid drive? The Panasonic one I described has precision machined steel helical gears. Their later unit uses only a single nylon gear in a single stage reduction, so efficient that they made it a feature of their sales promotion. And its reliability is legendary.

Compare that single stage gear wheel with a typical hub motor with an epicyclic, four gear wheels driving a hub shell toothed rack which is their fifth gear wheel. Some like Suntour and AKM even have stepped cogs for two steps of reduction using a total of nine toothed gear wheels !!

You see, completely the opposite of what you were trying to convince me, showing the flaw in selecting limited examples to do that.

In truth all kinds of e-bike motor have intrinsic inefficiencies. Hub motors with fixed internal reduction gearing don't adequately cover the e-bike motor operating range, ideally needing a choice of two gears. Hence Xionda and SRAM trying to address that.

Mid drives have a different efficiency problem, driving through the large number of gears a rider needs, when the motor, like the hub motor, only really needs two gears. That means they are at the mercy of the rider actually choosing the best gear for the motor all the time.

However, since the mid drive can have the two gears when the rider chooses correctly, it is more efficient than a single stage reduction hub motor across all usage circumstances. That is an absolute of physics.

When the mid drive rider doesn't choose the correct gear, that is rider inefficiency which shouldn't be confused with motor unit efficiencies.
.

I'm a huge fan of Panasonic as a company but they are not a major player in mid-drive motors today, prebuilt mid-drive ebikes are now more likely to be Bosch, Brose, Shimano and Yamaha etc. Many of these models are built for performance and use lighter materials and have lower sound levels. They do have nylon cogs and occasionally belts typically. If you are making a comparison of ebike motors surely you have to base it on what is in the marketplace and which models people are typically buying.

I'm not waffling at all. The point is most mid-drive motors are pedelecs so you are always assisting the motor because you have to pedal to get the ebike to function. Many hub motor ebikes are twist and go and you see many figures which are range when non-assisted by the rider which means far less miles. If you buy a geared hub motor ebike which can be very light its a far easier bike to move unassisted. You could use the motor only when you need it and get a huge range or if you have a direct drive hub motor which is a much heavier ebike you could use regen down the hills and ride it yourself on the flats under only your own power and then use the motor only for the hills to get a huge range out of it.

Scaling power through the gears is an advantage for sure but its not the full picture. If you look at the ebike marketplace and how ebikes are configured direct drive hub motor ebikes typically have the largest batteries fitted to them, then you have mid-drive and then geared hub motors which can come with tiny batteries and still give good range.

Whats more efficient a small town car that can do 60mpg average or a big executive car that can do 45mpg and has a more efficient engine but weighs twice as much and has a hugely complex engine with reliability issues to achieve that figure?

If the task is to get a person from one place to another in the most efficient way possible, energy, cost etc then the small car wins.

However again I totally accept the hill climbing benefits of more powerful mid-drive motors because the power is provided through the drivetrain but I don't think you can just isolate that benefit and focus on that solely and I don't think you can claim torque sensors as an exclusive benefit of mid-drive either.

Lets also not forget that because mid-drive motors scale their power through the gears this does mean much reduced power in higher gears so if you are riding on mostly flat surfaces or slight inclines a hub motor ebike can feel much more powerful and happier to assist at speed. You feel a sense that the ebike is much more powerful for general use. This can be ideal for those who are really struggling to assist themselves it could be someone incredibly weak, elderly or disabled in some way.

The calculations I've seen for Watt hours per mile for mid-drive motors where they are fitted with throttle's and can operate as twist and go ebikes did not show great Watt hours per mile the Wattage figures were quite high. Admittedly those ebikes were over 250W because that seems to be more a class of ebike sold in the US not restricted by 250W. It's difficult to make a comparison of unassisted range with mid-drive ebikes over here. The figures were easily beaten by lightweight geared hub motor ebikes with throttles which admittedly had smaller lighter batteries.

 

[egroover]

I'm a huge fan of Panasonic as a company but they are not a major player in mid-drive motors today, prebuilt mid-drive ebikes are now more likely to be Bosch, Brose, Shimano and Yamaha etc. Many of these models are built for performance and use lighter materials and have lower sound levels. They do have nylon cogs and occasionally belts typically. If you are making a comparison of ebike motors surely you have to base it on what is in the marketplace and which models people are typically buying.

I'm not waffling at all. The point is most mid-drive motors are pedelecs so you are always assisting the motor because you have to pedal to get the ebike to function. Many hub motor ebikes are twist and go and you see many figures which are range when non-assisted by the rider which means far less miles. If you buy a geared hub motor ebike which can be very light its a far easier bike to move unassisted. You could use the motor only when you need it and get a huge range or if you have a direct drive hub motor which is a much heavier ebike you could use regen down the hills and ride it yourself on the flats under only your own power and then use the motor only for the hills to get a huge range out of it.

Scaling power through the gears is an advantage for sure but its not the full picture. If you look at the ebike marketplace and how ebikes are configured direct drive hub motor ebikes typically have the largest batteries fitted to them, then you have mid-drive and then geared hub motors which can come with tiny batteries and still give good range.

Whats more efficient a small town car that can do 60mpg average or a big executive car that can do 45mpg and has a more efficient engine but weighs twice as much and has a hugely complex engine with reliability issues to achieve that figure?

If the task is to get a person from one place to another in the most efficient way possible, energy, cost etc then the small car wins.

However again I totally accept the hill climbing benefits of more powerful mid-drive motors because the power is provided through the drivetrain but I don't think you can just isolate that benefit and focus on that solely and I don't think you can claim torque sensors as an exclusive benefit of mid-drive either.

Lets also not forget that because mid-drive motors scale their power through the gears this does mean much reduced power in higher gears so if you are riding on mostly flat surfaces or slight inclines a hub motor ebike can feel much more powerful and happier to assist at speed. You feel a sense that the ebike is much more powerful for general use. This can be ideal for those who are really struggling to assist themselves it could be someone incredibly weak, elderly or disabled in some way.

The calculations I've seen for Watt hours per mile for mid-drive motors where they are fitted with throttle's and can operate as twist and go ebikes did not show great Watt hours per mile the Wattage figures were quite high. Admittedly those ebikes were over 250W because that seems to be more a class of ebike sold in the US not restricted by 250W. It's difficult to make a comparison of unassisted range with mid-drive ebikes over here. The figures were easily beaten by lightweight geared hub motor ebikes with throttles which admittedly had smaller lighter batteries.

I can average 10wh per mile on both my hub motor torque sensor Carrera Crossfire-e as I can on my 250w 15.5mph limited Bafang BBS01 cadence sensor mid drive conversion bike on the same route/conditions
They deliver the power differently but I put in the same effort to go the same distance I have found. Nothing scientific just my personal real world experience. The benefit to me of my mid-drive is more grunt up hills and off road, lower gearing, no spokes snapping, and easier puncture repairs and maintenance.
My Bafang BBS01 has so far done 2700 trouble free miles. I have another complete brand new unit purchased last year for £230 as a spare with display etc ready to swap if needed. Just bought a new 9 speed chain and Sunrace 11-40t cassette for £30 all in on Amazon....

happy, care free, cheap mid drive miles

 

[sjpt]

Whats more efficient a small town car that can do 60mpg average or a big executive car that can do 45mpg and has a more efficient engine but weighs twice as much and has a hugely complex engine with reliability issues to achieve that figure?

Irrelevant anecdote from the days British car unreliability was only rivaled by that of the US.

A posh Rover was sent to the airport to pick up and impress foreign dignitaries. They were suitably impressed until the end of the ride; it proved impossible to open the back doors so that they had to clamber over to the front.