Gears, How Many is Too Many?

[Cyclezee]

I am wondering what members feel is the correct number of gears to have on an electrically assissted bike and why?

 

[flecc]

My general opinion is six, but it depends on the range of the gears. The minimum range to cover most terrains is 250%, but 300% is better. The latter is difficult to achieve with a six gear set, especially with a multi-sprocket freewheel, so 7 or 8 is sometimes necessary.

With hub gears, only the SRAM P5 covers 250% with less than six and I think it's discontinued now. So it means an eight speed hub to get 300% range and reliabity.

 

[KirstinS]

essentially, what he said ^ ! (flecc) . Peronally I have become a little evangelical on the alfine 8 hub. It is utterly bullet proof, never misses a beat, chnage when stationary. All this for a little extra weight..........which matters even less on an ebike. Also one less lever on the handle bars to make way for a throttle/other indicator. Given that ebikes already have more on them to go wrong than a normal bike one less thing to worry about (whilst still proving the 300% range) seems the way forward. There is only one problem and it is a biggie - you are stuck with front wheel drive (or a crank I guess). That may be an issue for some

 

[Jimod]

I have 9 gears on mine and I use them all everytime I go out. I live in the hills and need the lowest to start off and the highest when going on the flat or a slight downhill stretch. Generally though I'm in the middle 4 gears as the hills here have many different gradients as you climb them.
I think any less (for me) would put me off the bike as my middle 4 would then be spaced too far apart to be smooth uphill when the gradient changes.

 

[smudger1956]

I have 7 gears, which I find quite adequate.

 

[Cyclezee]

It is looking like 7, 8 or 9 is the maximum requirement, kind of what I expected.

Kirstin mentions the weight of the Alfine 8 hub, but it is no where near as heavy as a Nu Vinci CVT, I had a good look at one when I was in China a few weeks ago and although I don't know the weight, it is a heavy lump.

 

[flecc]

Kirstin mentions the weight of the Alfine 8 hub, but it is no where near as heavy as a Nu Vinci CVT, I had a good look at one when I was in China a few weeks ago and although I don't know the weight, it is a heavy lump.

The NuVinci CVT hub only was 3850 gms, but later reduced to approximately 3200 gms.

Rohloff hub only, 1700 gms

Alfine complete, 1590 gms

SRAM i-motion 9 speed complete, 1900 gms

 

[funkylyn]

I have the Shimano nexus 8 .....I find I use them all and I love hub gears, I dont think I could ever contemplate a bike without them now.

So easy, once I got used to using them with the crank motor of the Tonaro, and whilst this bike may not be perfect for some ........for me the advantages of hub gears, crank drive AND a throttle outweighed (sic) the total weight of the bike, which although just about acceptable, obviously I would prefer it to weigh 20kgs or less...not 25kgs.....but, hey ho, you sometimes find you have to live with some imperfections in life.

So, anyway.....my vote is for 8 gears

Lynda

 

[laroche]

I use a range of 210% on my Cytronex Trek, from 41 to 85" or sprockets 2 to 7 on the middle chain wheel. That covers everything from the steepest hill I encounter to the full 15mph (which requires 60RPM pedal speed). The six gears in that range don't feel quite enough; some of the gaps seem a bit big (though I don't bother to fiddle about with the front derailleur as well to get the 'half' gears between them). So, for me, seven would seem about right with a single chain ring dead in line with the middle cog (only possible with an odd number) which, in my case, needs to be 55 or 56" (the gear I use the most).

However, that arrangement leaves me a bit short at the bottom end for emergencies. When I ride non-electric (battery removed and front wheel swapped), I go right down to 28" on a steep ascent. Using that low and the 85" top equates to a near 300% range. So, if I would be happy with seven gears for 210% I would require, presumably, ten for 300%. With a derailleur, I'd probably settle for nine to centre the chain line on my favourite gear and reduce the chances of the chain coming off.


But that's me being realistic and practical. Something in the remnants of my soul says the real answer, the best answer, is one.

Of course, one gear cannot cover the 0-15mph we are allowed; even a 73" gear needs 70RPM to hit the top speed and would be nigh on useless for hills. But supposing, just supposing, we were to relax our seeming fixation with the legal maximum speed and, instead, were prepared to settle for less. How much slower would we have to go before one gear became realistic? With a gear of 54" (about the same as single speed mountain bikers use) 60RPM produces a speed of nearly 9.6mph and, with 60", about 10.6mph. Is that sort of thing really so horrid? If the legal maximum speed were 11mph would none of us bother with electric bikes? There are more, far more, electric bikes in China than elsewhere and the legal maximum is 12.5mph.

How to get it? Simple, a combination of shrunken wheels and a slow spinning motor. A 20" wheel (actually, most of them are not even 19") turning at 160RPM (the slowest Tongxin) goes 10.5mph and, at 175RPM, 11.4mph (knock 5% off the speeds for 19"). What's wrong with that? Sure, it ain't fast, but it would torque its way up hills for England.

All of which suggests the best electric bike possible would be a single speed Moulton (if only it were not so heavy)............ But that's just my soul talking.

 

[Kudoscycles]

With hub drive I like the 8 speed Nexus or 9 speed Deore but am now looking at crank drive and these are a different riding style,more like sports riding with help and 24 or 27 speed is prefered.
Dave
KudosCycles

 

[flecc]

But supposing, just supposing, we were to relax our seeming fixation with the legal maximum speed and, instead, were prepared to settle for less. How much slower would we have to go before one gear became realistic? With a gear of 54" (about the same as single speed mountain bikers use) 60RPM produces a speed of nearly 9.6mph and, with 60", about 10.6mph. Is that sort of thing really so horrid? If the legal maximum speed were 11mph would none of us bother with electric bikes? There are more, far more, electric bikes in China than elsewhere and the legal maximum is 12.5mph.

I agree that an assist motor just for the hills does make sense, and in Britain our original assist speed limit was 12 mph. Heinzmann make a motor for 11.5 mph in standard wheels and there is one eZee model with assist only to 12 mph, both these with great hill climb ability.

The Chinese example isn't a good comparison though, their speed limit is universally ignored and the machines they ride are more like mopeds, circa 700 watts and usually ridden at nearer 20 mph without pedalling.

 

[timidtom]

Maybe five or six, wide ratio. Mind you, we cycle in leafy Cheshire, not the Welsh Alps ...

 

[laroche]

flecc

Intriguing that it used to be 12mph. When was it changed to 15mph and, perhaps more interesting, why?

So that's why the Chinese have so many mega-wattage motors on the market! Perhaps the apparent official tolerance of such grossly overpowered bikes originates in the speed at which road infrastructure must be built to keep pace with rapid economic growth and car ownership. From the planners' perspective, anything (almost) on two wheels may be worth tolerating if it means fewer motor vehicles.

 

[NRG]

IME 8 is the absolute minimum I would want or could get away with, this would be with motor assistance. Without assistance IE flat battery, then a lower set is required and 8 would not cut it, in this case I would prefer a 27 speed choice...I've benefitted from this on my Alien GSII on more than one occasion!

 

[mike killay]

I have 8 gears on my Tonaro (crank drive). 33 to 99 inches.
Normally I never use 1st, 5th or 7th
Even with my feeble pedalling I don't need them all.

 

[NRG]

Try it with a flat battery!

 

[bode]

I have 7 hub gears from 39"-96" (246%), and that is absolutely fine, because the highest and lowest gears suit me. Quite honestly, I would probably be quite happy with just 3 gears across that sort of ratio, but that is because of the way I use the motor (a lot). People who prefer to do more pedalling and only to use the motor to help out occasionally will obviously need more gears to maximise their effort.

But I think that for practical and commercial purposes for a fairly standard e-bike 6 to 8 gears would be best, as seems to be the consensus here.

 

[jerrysimon]

Two, one to set off and one for cruising, in flat Cambridge anyway

Regards

Jerry

 

[flecc]

flecc

Intriguing that it used to be 12mph. When was it changed to 15mph and, perhaps more interesting, why?

So that's why the Chinese have so many mega-wattage motors on the market! Perhaps the apparent official tolerance of such grossly overpowered bikes originates in the speed at which road infrastructure must be built to keep pace with rapid economic growth and car ownership. From the planners' perspective, anything (almost) on two wheels may be worth tolerating if it means fewer motor vehicles.

The original 12 mph limit changed in 1988, part of the harmonisation of transport with the EU. There are further harmonisation steps planned in the near future for e-bikes.

The Chinese law is strange, the 700 watts with the 12 mph limit is official. However, the attitude has changed due to the high level of accidents and they are starting to crack down, but against huge resistance. Currently they want to adopt EU style law to bring things under control, but it will take time. That's likely to kill off much of their home market, but I don't think they care since they have become even more car biased than the USA. A number of cities have banned e-bikes since "they get in the way of cars", and in a number of other cities e-bikes are banned from some main routes, particularly the new multi-lane city highways.

How the world has changed, the West cycling and China driving cars! They'll be sending us food aid next!

 

[amigafan2003]

I have 27gears on mine but I only ever use the big ring at the front.

Even with 9spds at the rear however I still find myself wanting a couple of the ratios to have another gear in between them to maintain a nice cadence. Might upgrade to a dual chainset and 10spd close ratio rear.