Hub or Derailleur, Which Is Best?

[flash]

I am not an engineer nor even a gifted cyclist, however I don't have to be either to see potential for failure in a transmission system designed specifically for personal pedal power. None of the crank manf so far as Im aware have upgraded their derailleur systems to cope with the additional demands of electric assist and I mean only to relate my personal concerns in that regard and suggest the nuvinci as a sensible alternative. You dont have to be a francophobe traindriver to dislike derailleurs.............

Derailleur systems are the ones used by the top professional cycling teams. A good professional cyclist climbing an Alpine stage of the Tour de France will generate 400 to 500 watts. We very rarely see failure of derailleur gear systems on these stages. A good club racing cyclist will probably generate 200 - 250 watts so even these powerhouses should be OK with a 250 watt motor. I would guess (which is all I can do) that the average Ebiker will not produce much more than 180 watts of power Some ideas of cyclist's wattage are - You can get quite a good workout at 200 watts, push a mean time trial at 300 watts, and tour the Alps fast at 400 watts. I would imagine that the average rider with using a crank motor will not damage a derailleur system. However I have no idea what wattage a hub gear can with stand.
Having said that I prefer hub gears and have used a nexus 7 speed for about 3 years on my unpowered bike.

Bicycle Power – How many Watts can you produce? | mapawatt

 

[tillson]

I have used both derailleurs and hub gears. The derailleurs were on an unpowered bike and the Shimano Alfine 8 speed is on my crank driven hub motored bike.

For daily use on a utility type commuting bike where slightly less efficiency is of no significance, hub gears are by far the better option for reasons of low maintenance, reliability and ease of use. Changing down when going up hill doesn't cause any serious loss of momentum once you get use to them and learn how its done. My Alfine has taken me over 10000 miles without a hint of trouble and I don't recall any Alfine failures being reported on here, so the hub gear / crank drive failure scaremongering by business rivals is probably just that.

 

[indalo]

Due to injury, I shall be unable to compete in this year's TDF beginning on June 30th. To be honest, I'm not sure I would be able to keep up with the major teams as my Nexus 8 would put me at a slight disadvantage against their riders, all equipped with derailleurs. All those momentary pauses add up to several precious seconds!

Seriously though, given that the TDF riders are the world's elite and are supreme athletes, why do they need gears? They'll be using electric-assist next.....where will it all end!

Indalo

 

[flecc]

I am not an engineer nor even a gifted cyclist, however I don't have to be either to see potential for failure in a transmission system designed specifically for personal pedal power. None of the crank manf so far as Im aware have upgraded their derailleur systems to cope with the additional demands of electric assist and I mean only to relate my personal concerns in that regard and suggest the nuvinci as a sensible alternative. You dont have to be a francophobe traindriver to dislike derailleurs.............

You are very much misreading this situation. As flash has pointed out above, derailleurs are very capable of transmitting powers which can be well in excess of that a crank drive e-bike suffers. Short term peak powers of the top race riders can easily exceed 1000 watts, compare that with an average cylist's absolute short term peak of 300 watts with a typical 400 watt crank drive peak. Now consider that the top race riders are using skinny 9/10 speed chain and sprockets while the e-bike is mainly using the thicker stronger 7/8 speed chain and sprockets. Refer back to the early stages this discussion and you'll see it's the hub gears that give rise for concern, not derailleurs.

And this support for derailleur strength comes from a confirmed hub gear fan, I think them far more civilised and sensible for everyday use. The NuVinci CVT is extremely heavy, very inefficient and expensive, none of which adds up to a sensible choice for cycling. The power of the average cyclist added to the power available from legal e-bikes is very limited, every watt is precious and squandering them through an unnecessarily inefficient transmission doesn't make sense.

 

[JuicyBike]

For me, this issue is all about the compromise of either a crank motor (as yet in its early development and still expensive) or a front drive, both of which systems are required for hub gears, or the use of a rear wheel hub motor.

The benefit of the hub motor lays with the fundamental design of the bike frame, designed to be pushed, not pulled.

Front wheel drive (the cost-effective way to introduce a motor in comparison to crank drives) places stresses on the frame, particularly around the headset, and effects the balance and stability of the bike, especially on loose surfaces.

So, for the benefit of cost, stability and frame stress I can only go with the rear hub motor, which leads to derailleur gears - fundamentally easy to maintain, tweak and replace at low cost.

Add a stainless steel chain (as we do), requiring little oil, then wear and tare on the gears becomes even less as the chain picks up little dirt and grit.

Derailleurs, stainless chain and rear hub motor it is, for me!

 

[indalo]

And this support for derailleur strength comes from a confirmed hub gear fan, I think them far more civilised and sensible for everyday use.

Yes Flecc, for me you've hit the nail on the head there. All but one of my bikes are derailleur-equipped, the old Gazelle being the only one with the delightful Nexus 8 hub. The leisure and utility aspects of cycling including gentle touring are the real world for most ebike owners and hub gears are simply perfect for that. Of course, there are some who do commute hard and fast every day who nevertheless feel the need for a bit of electrical assistance. I'd guess some of those would prefer derailleur transmission.

Indalo

 

[mike killay]

From an engineering point of view, a derailleur is a horror. It pulls a chain sideways off a cog and hopes that it will ride onto the next without trouble. The chain basically is only designed to flex in the direction of the cogs and not sideways.
The early models were not good but they worked. Over the years there were various advancements. Chains that could bend sideways, chains that could transmit power when the cog and chain wheel were not in line, cogs with ramps to help the change over, and probably the biggest change came when the old levers fitted to the down tube were replaced by indexed levers on the handlebars.
Derailleurs are exposed to all the road dirt and wet, muck gets into them and grinds away at the cogs, which are thinner than a hub gear ones.
All in all, they are dreadful from an engineering point of view. Add to that the fact that they have to be pre-changed before stopping and you wonder how they ever became so successful.
But, they work and they work really well. They are easy and cheap to repair, so they get my vote.
Truly, a triumph of practicality over design!!!

 

[hech]

Changing down on a steep hill is for me a teeth gritting sprocket gnashing experience which jus dont sound good. I dont doubt the reliability, durability or efficiency of the derailleur transmission system. Perhaps if I get rid of the pedelec sensor and ride on throttle alone I would be able to power down whilst downshifting. The more power going thro the chain, the more of an issue this can be, and at 1000watts,it really is an issue. Would love to try another hub system to see how they cope but I have heard that cvt is the way to go.

 

[hech]

http://endless-sphere.com/forums/viewtopic.php?f=28&t=38412[/URL]

 

[Wisper Bikes]

I can echo that Tillson's remarks, we have sold 1000s of Alfine Hubs now without one single internal gear problem. I should also add that we have not had any issues with the frame due to the front motor pulling the bike along, in fact I think the drive being split between the rider power at the back and electronic power at the front is a good balance. I believe that for the average electric biker, a hub is a good option. Giving total flexibility over when gear changes can be made and on the 8 speed Shimano models over 300% range. Couple to this the fact that only very minimal maintenance or adjustment is necessary.

The Alfine used on our bikes is simply a more refined version of the Nexus but both are superb pieces of machinery. The problem of course is they are expensive!

All said we still sell more rear motored derailiure bikes than hub geared bikes but they are course cheaper, so maybe both options have just about equal merit?

All the best

David

 

[Wisper Bikes]

Hi Hech, here is the link;

Endless-sphere.com • View topic - RMartin R10 running at 1800Watts through Nuvinci N360

 

[flecc]

For me, this issue is all about the compromise of either a crank motor (as yet in its early development and still expensive) or a front drive, both of which systems are required for hub gears, or the use of a rear wheel hub motor.

The benefit of the hub motor lays with the fundamental design of the bike frame, designed to be pushed, not pulled.

Front wheel drive (the cost-effective way to introduce a motor in comparison to crank drives) places stresses on the frame, particularly around the headset, and effects the balance and stability of the bike, especially on loose surfaces.

So, for the benefit of cost, stability and frame stress I can only go with the rear hub motor, which leads to derailleur gears - fundamentally easy to maintain, tweak and replace at low cost.

Add a stainless steel chain (as we do), requiring little oil, then wear and tare on the gears becomes even less as the chain picks up little dirt and grit.

Derailleurs, stainless chain and rear hub motor it is, for me!

I'm with you on the rear wheel for hub drives which normally means no hub gears. However the inherent near 100% efficiency of chain and sprocket drive means an intermediate "hub" gear in a two chain system is entirely practical. It just needs someone with the courage to do it, other than the odd amateurs who have done so already.

I'm not with your statement that crank drive is "as yet in its early development", clearly not true. The earliest e-bikes were commonly crank drive, hub motors trailing along much later. Back in the 1990s crank drive were mainstream with sophisticated bevel drive examples from Yamaha, Giant, Aprilia and Oxygen, plus secondary chain parallel drives from TGA and others and a unitary crank drive from BikeTec Flyer. Then at the turn of the millennium Panasonic introduced the sophisticated parallel single chain drive unit with it's second generation taking over five years ago. Three years ago Yamaha followed, then two years ago Daum, both very sophisticated units.

Hub motors only succeeded because they were much cheaper to make, so either much more profitable or more suitable for opening up budget markets.
.

 

[Wisper Bikes]

And of course they are more suitable for riders who prefer throttle only? I also believe they are easier to maintain?

Being less expensive they allow manufacturers to spend more on the traditional bikey bits, or providing better service!

All the best

David

 

[flecc]

I have heard that cvt is the way to go.

I've never heard that from any source other than NuVinci Hech, you are clearly very biased in favour of the concept. There's no doubt that it is a brilliant concept, painstakingly brought to fruition and since improved with a small weight reduction, and I have nothing other than admiration for the designers and engineers who have realised it. But I don't let that cloud my engineer's and cyclist's judgement that it's fundamentally unsuitable for cycling.

 

[flecc]

And of course they are more suitable for riders who prefer throttle only? I also believe they are easier to maintain?

Not really David. The EU and Japanese laws are mainly why they have been pedelec, but they are just as well suited to throttles as the Tonaro, Cyclone, Optibike and Eclipse systems show.

You may find this a hot potato, but the sophisticated crank drives are far more reliable so maintenance isn't a problem or even necessary. They don't have the small nylon epicyclic gears that wear out, the integrated one piece sealed construction means they don't suffer the water and cabling problems that disparate component hub drives suffer from, and the motor's Hall sensor arrangement can be much more robust. It all adds up to a decade or more of carefree daily use without attention in many cases.

 

[hech]

The RMartin R10 bike in the article I referenced is of course the same as our own Tonaro Bighit. The power level he quotes is far in excess of what most commonly experience, or for that matter, call cycling.

 

[indalo]

All said we still sell more rear motored derailiure bikes than hub geared bikes but they are course cheaper, so maybe both options have just about equal merit?

All the best

David

Henry Kissinger couldn't have put that any better David!

Indalo

 

[flecc]

The RMartin R10 bike in the article I referenced is of course the same as our own Tonaro Bighit. The power level he quotes is far in excess of what most commonly experience, or for that matter, call cycling.

This isn't in dispute Hech, the NuVinci is more capable than any hub gear at transmitting high power. As I've repeatedly said, it's the inefficiency losses, weight and cost which make it unsuitable for cycling. It's a good transmission for use with much higher powers than cycling or e-biking can provide and I understand they are exploring other applications.

 

[Wisper Bikes]

Thanks, Indalo, however Flecc is certainly the master of diplomacy, judging him by his resonse!

We have had great success with hub motors which have proved to be very reliable thus far, in fact I don't think we have had to replace any nylon gears apart from on the very early bikes. We will will continue to work with them as they improve and develop. I visited Dapu a couple of weeks ago to see the new motor for 2013, it is amazingly "torquey" and virtually silent, a great improvement on what is already the supreme hub motor IMO.

We are currently looking at introducing a crank drive Wisper for 2013/14. I therefore find myself in a steep learning curve so any help is much appreciated and I am certainly not too proud to learn! We are looking at the possibility of using the new version of the NuVinci hub which is much lighter and needs less twisting to move through the gears. However after reading Flecc's comments I have some new questions for them!

All the best

David

 

[NRG]

I think the NuVinci hub is fine, as Flecc hinted at, as long as you are using the motor power to assist you. Under your own steam weight and inefficiency come into play and maybe its not the best option in this case...