Chinese crank drives,throttles and gears.

[hoppy]

No problem on Tonaros.If the Tourney gears aren't good enough don't use them!'

 

[flecc]

My point is if the power of the Tonaro Motor, Bosch Motor and Panasonic motor are roughly the same, I can't see what the problem is.

From what I've heard from impartial and very experienced people, the Tonaro is definitely not a particularly powerful system, torque is good and it climbs slowly, but it's no record breaker.

In contrast, when the Bosch system was first introduced in Germany it got a reputation for destroying chains very quickly, so it was modified.

Hub gear manufacturers are very sensitive about torque and have rules about how low a bottom gear is allowed for systems they supply, Shimano for example specifying the limits to the sprocket pairings that can be used. These rules are for unassisted bikes and it's possible to break the rules on those, so one can see how much more tricky it can be with assist power. Any long term regular reader of Velovision will also know about the history of hub gear failures on hard-worked unassisted bikes. Since the Inter hub series, Shimano have increased the diameter of their newer hub gears to increase the strength of their components and have twice modified their 8 speed for this purpose, the first modification specifically to address a series of failures after it's introduction.

Historically Shimano withdrew their 4 speed Nexus Inter hub specifically because they were being destroyed by the Giant Lafree's Panasonic unit, and that was the lower powered early unit without a high power mode. Once again this shows there is a criticality with power assistance through hub gears, as well as an additional wear problem on derailleurs. SRAM who have suffered a number of failures on their S5 and S7 gear hubs are currently replacing the entire range with new designs to be announced. They had introduced one new design, the 9 speed I-motion, but it only lived for a very short time before SRAM withdrew it from the market.

I love hub gears and overall prefer them, but they do have their limitations with power assistance that can make them very apparent. Some ask for evidence from the manufacturers, but Shimano in particular are very sensitive about failures and keep very quiet about them, so its not surprising that SRAM and Sunrace-Sturmey follow suit in this competitive market.

 

[tillson]

Hub gear manufacturers are very sensitive about torque and have rules about how low a bottom gear is allowed for systems they supply, Shimano for example specifying the limits to the sprocket pairings that can be used. These rules are for unassisted bikes and it's possible to break the rules on those, so one can see how much more tricky it can be with assist power.

That makes sense. I can see there only being a problem with high powered, S class, bikes or standard ones where the torque is multiplied by an inappropriate combination of sprockets.

 

[flecc]

The safest bet for a hub gear with power assist is the NuVinci CVT, far stronger than any other. By reputation the frighteningly expensive Rohloff might be a good choice for the well-heeled.

 

[Marctwo]

Now that I know this exists, I won't be happy till I've got one.

NuVinci® Harmony

 

[Kudoscycles]

The full story-
First of all don't shoot the messenger.
My email inbox has many offers for cheap bikes using the TCM motor-in the usual chinese way the manufacturing company comes up with a good seller and then tries to sell it to everybody-many of these companies may never have built a bike, never mind tested one-the graphics are photoshopped from someone elses frame and the spec has been thrown together to what is to hand.
Over the next few months,probably immediately after the Shanghai Cycle show the UK will be full of cheap chinese crank drive bikes of varying assembly quality.
At the moment I have no intention of putting Shimano hub gears with the TCM crank drive motor,its not a proven combination and the hub gears are out of character with a performance style bike-I emphasise I have no reason,at this time,to reject the combination.
We use the cheap Tourney gears on a number of our hub drive bikes with no problems. I must say the change is not as nice as on the Alivio gears but the quality of the shifter and quality of cables is as much importance as the gears themselves-for that reason on our new Cobra bike we rejected the cheap SIS index shifters in favour of the Shimano TX50 and TX35 shifters.
Look around Halfords and all the low end non assisted bikes use the Tourney system,its a budget system and made to a price,with care and good maintenance it is ok.
We didn't experience any problems until we combined these gears with the TCM crank motor.
The manufacturer of the Arriba/Tornado/Cobra and Ibex bikes is one of the largest in China-I must say they are a 'pain in the bum' when it comes to quality control,every element has to go through an extended quality control procedure through a high number of test cycles-I say pain because it extends the delivery time considerably.
I must say that I have never seen a 250 watt Bosch system fed through Tourney gears.
You guys are demanding more torque from these crank drive motors and are therefore,especially with a powerful rider,placing more demands on the transmission system-obviously if you don't pedal the torque is considerably reduced but that surely defeats the object of a pedelec.
I must say that the BPM hub drive motor with a torque sensing pedal is so good that unless you spend your whole time going up hills slowly it would be my choice over the crank drive,but that is a personal view-at the Excel Show the split was about 60-40 in favour of crank drive.
Before anyone asks-the TCM motor has passed EN15194.
Dave
Kudoscycles

 

[flecc]

Now that I know this exists, I won't be happy till I've got one.

NuVinci® Harmony

It is a heavier hub, and despite their claims I found it quite inefficient. If you've got adequate assist power, no problem, but I would not use one on an unassisted bike. Both reviews I've seen (Velovision, A to B) also complain of the apparent higher drag than normal bike gears, it's certainly very much higher than with derailleurs, and one reviewer actually said it's difficult to escape from the pedalling through treacle impression.

 

[Deleted member 4366]

From what I've heard from impartial and very experienced people, the Tonaro is definitely not a particularly powerful system, torque is good and it climbs slowly, but it's no record breaker.

The recent comparisons that I've heard (including a German one) rate the Tonaro as having the higher torque. Wasn't it uprated from the original 200w to 250w? Maybe your reports are the old version.

 

[flecc]

The recent comparisons that I've heard (including a German one) rate the Tonaro as having the higher torque. Wasn't it uprated from the original 200w to 250w? Maybe your reports are the old version.

It might have been for some, but the most recent was an agent who found the later version low powered and quite slow. Always difficult to judge with opinions of course, it would depend on what he was used to.

 

[tillson]

Is motor torque a complete red-herring? Surely it's the motor's power which is important. With the correct gearing, you could make a 10 Watt motor produce more torque on a shaft than a 1 KW motor.

 

[hech]

From what I've heard from impartial and very experienced people, the Tonaro is definitely not a particularly powerful system, torque is good and it climbs slowly, but it's no record breaker.

In contrast, when the Bosch system was first introduced in Germany it got a reputation for destroying chains very quickly, so it was modified."

Flecc can I ask who these impartial and experienced people are? At the risk of becoming the ultimate Tonaro bore of the forum can I reiterate the stock, peak power of the Tonaro is around 700watts ~ 40v*17amps according to the watt-meter. Trouble is noone who owns a Bosch ever bothers to fit a meter and validate the manf claims. My contention is that certification is probably a little less fastidious in the far-east than is likely in Germany. I dont doubt that the Bosch system is probably more efficient at converting battery power to the wheel but it wont be by that much. Nor do I think the cheapish tonaro battery would be able to match the C-rate of the Bosch cells. As you know the power output of all these bike motors is determined by the controller and whatever current limit the programmer dials in. The controller can easily be dialled up to deliver 1000watts for instance but no-one would get their certificate then. For the record I have broken two freewheels and a chain on my Tonaro, but all while running at non certified power levels. It's all a question of tuning, it really doesn't matter if it's an old truck windscreenwiper motor.

 

[Marctwo]

It is a heavier hub, and despite their claims I found it quite inefficient. If you've got adequate assist power, no problem, but I would not use one on an unassisted bike. Both reviews I've seen (Velovision, A to B) also complain of the apparent higher drag than normal bike gears, it's certainly very much higher than with derailleurs, and one reviewer actually said it's difficult to escape from the pedalling through treacle impression.

That's a shame.

I wonder how much of this impression is psychological due to pedal speed not increasing with effort/bike speed...

 

[flecc]

Is motor torque a complete red-herring? Surely it's the motor's power which is important. With the correct gearing, you could make a 10 Watt motor produce more torque on a shaft than a 1 KW motor.

Not altogether, though a figure in isolation isn't much use. Where the power comes in is important in relation to the torque, one without the other is no use for climbing. Torque is always at the maximum at zero revs, but it only really becomes useful when there's a coincidence of the torque and power at roughly equal optimums, usually about half of maximum speed on hub motor bikes. An e-bike like the old heavy Powabyke which had a high peak power coming in early at 7 mph made it an excellent climber, despite the huge weight. A few hub motored bikes which have the peak power coming in late at anything from 10 to 13 mph were correspondingly poor climbers, the later the power peak, the less climb ability.

So to judge the climb ability of a hub motored e-bike it's better if we can see a torque/power graph.

With crank drives it's more complicated since they can run at near the optimum torque/power optimum almost regardless of speed, just by choosing a suitable gear, this enabling them to use lower peak powers. There is a snag in this since the pedalling cadence best for the motor might not be best for the rider, a snag that could only be overcome by variable gearing from the motor into the chain, too complex of course.

 

[Deleted member 4366]

Is motor torque a complete red-herring? Surely it's the motor's power which is important. With the correct gearing, you could make a 10 Watt motor produce more torque on a shaft than a 1 KW motor.

It's a funny thing this torque and power. I don't know whether this helps: Torque is the force which if it goes above a level will strip your gears. The amount of power you have determines how quickly they'll strip once you've reached that level. So, in summary, power is the rate at which you apply torque.

 

[flecc]

That's a shame.

I wonder how much of this impression is psychological due to pedal speed not increasing with effort/bike speed...

Definitely not for me, and the two reviews I quoted were by David Henshaw of A to B and Peter Eland of Velovision, both hub gear fans and hugely experienced strong cyclists.

The inefficiency through drag is logical, since the NuVinci depends entirely for it's drive by compression of a fluid into a near solid state at the contact points on both sides of the six drive balls and their tracks. This is a continuous process and such compressions must absorb quite a lot of energy. Gear wheel teeth have no such loss, only the friction as they engage which is minor in comparison.

 

[flecc]

Flecc can I ask who these impartial and experienced people are? At the risk of becoming the ultimate Tonaro bore of the forum can I reiterate the stock, peak power of the Tonaro is around 700watts ~ 40v*17amps according to the watt-meter.

As you see from my reply to Marctwo, I'm usually happy to disclose, but in the case of the Tonaro I've quoted from private communications, including those who actually sell the product in different places so I can't undermine.

I know the Tonaro torque capability is high, and certainly that gross power you quote is very high, meaning a net power of over 500 watts, assuming the battery can continue to deliver at that rate. That seems to be at the Bosch levels or a little above, but of course the bike weight comes into the performance and feel. Some of the Tonaro models are very heavy while some of the Bosch powered ones are very light, giving different impressions in riding them. As I remarked to Dave, difficult to judge from others impressions.

 

[Marctwo]

Definitely not for me, and the two reviews I quoted were by David Henshaw of A to B and Peter Eland of Velovision, both hub gear fans and hugely experienced strong cyclists.

The inefficiency through drag is logical, since the NuVinci depends entirely for it's drive by compression of a fluid into a near solid state at the contact points on both sides of the six drive balls and their tracks. This is a continuous process and such compressions must absorb quite a lot of energy. Gear wheel teeth have no such loss, only the friction as they engage which is minor in comparison.

I was reading about how they worked and thought it sounded quite good. But now that you mention it, I'd imagine it would impact on the efficiency.

I assume the manual N360 suffers in the same way as it's the same mechanism...

 

[BAH48]

I like the phrase " Power is what you read about, but torque is what you feel"

 

[Woosh]

I'm not technical (as you know) but as i understand it, it doesn't matter which derailleur or hub gearbox you may have.
Experienced riders will know that squeezing the brakes slightly while changing gear will cut out the motor and reduce wear and tear on the transmission. They'll also know how to adjust the gear cable if necessary.

I think the potential problem would be when the rider does not know how to adjust his/her gear cable.
If the chain jumps repeatedly off the derailleur cogs or the freewheel, the derailleur and freewheel will soon be wrecked, or the hub gearbox will break. Question is...is this a warranty issue?

Hatti

 

[flecc]

I'm not technical (as you know) but as i understand it, it doesn't matter which derailleur or hub gearbox you may have.
Experienced riders will know that squeezing the brakes slightly while changing gear will cut out the motor and reduce wear and tear on the transmission.

The e-bikes with the sophisticated crank drive motors like the Panasonic, Bosch, Impulse, Daum etc don't have brake cutouts Hatti, not necessary with pedelec only control, so this trick is not possible.