Gear options for a crank bike - what's the mose versatile or robust.

OK,

I have been lurking a while and first posted recently with an introduction. I have picked up a little knowledge which may be a dangerous thing.

 

I think a crank bike will probably suit me best but with only one chainwheel the gearing options seem to be limited, 7 or 8 typically.

 

If you want more ratios whats best, Alfine 11, SRAM dual drive, Nuvinci? I guess there are others available, do not want to upset any one.

I think I am looking for versatility if I am honest.

 

If I dont need more gears then why would I chooses a Kalkhoff C11 over a C8 just as an example.

 

Dave

If I dont need more gears then why would I chooses a Kalkhoff C11 over a C8 just as an example.

 

It's a very good question and one I spent ages deliberating over.

 

The bike spec is a bit tastier. HS33 rather than HS11 brakes, nicer saddle, Verso III Magnesium TnL rather than Suntour fork. It's also in Mondobrown rather than black/white - which I think is very classy but you either like or you don't. When you see them next to each other you can judge for yourself which you prefer.

 

The big plus on the C11 is the LCD output which gives live monitoring of battery usage, a permanent mileometer and trip resettable one (like a car), speedo, average speed, remaining battery and power selector all in one on a decent sized easy to read screen which is backlit if you need it.

 

The Alfine C11 gives much more riding control than the C8 so you can get your riding fine-tuned for best performance of the bike. Having it just makes you feel more confident that if you want to stretch the boundaries a bit then you can and the bike isn't going to limit that. The Alfine 11-speed has been used on round the world tours so it's pretty capable but all the top-end hub gear systems have their quirks.

 

I very nearly bought the C8 off plan because the price differential was a lot but after test riding them side by side in Birmingham fell in love with the C11 and handed over the dosh. You just can't tell from a picture or write-up, only by getting on one and trying it out. They just felt leagues apart - one was a really good bike and the other was exceptional

 

If money were no object I'd try to get a Rohloff-hub crank drive. Kalkhoff don't do them in e-bikes unfortunately.

Edited January 30, 201313 yr by 103Alex1

The fact that the assist power helps to bridge gear gaps makes a large number of gears less necessary than on an unpowered bike. The gear range doesn't need to be quite so great either, since the assist power reduces the need for very low gears. In most areas where there are none of the most extreme hills, a Shimano 8 speed hub gear or derailleur with equivalent gear range is sufficient.

 

To help you judge, here's the gear range on the following hub gears:

 

Shimano Nexus 8 speed = 307%

 

NuVinci CVT = 350%

 

Shimano Nexus 11 speed hub = 409%

 

Rohloff Speedhub = 526%

 

As good as the Rohloff may be, I think it is overkill on an electric assisted bike.

The fact that the assist power helps to bridge gear gaps makes a large number of gears less necessary than on an unpowered bike.

 

As one who has a phobia about peddling I'm almost kinda convinced that 3 gears is adequate.

 

My next project will be to remove the derailer / wheel and fit a Sturmey Archer 3 speed to the crank drive bike..

 

I wonder what noise a murdered Sturmey Archer makes, lol

I wonder what noise a murdered Sturmey Archer makes, lol

 

Graunch is the word that springs to mind.

 

I rode a Giant Lafree Twist with the Nexus three speed hub in my hilly North Downs area for a year without breaking it, but changed that for an SRAM 5 speed hub to help with my heavy goods trailer towing. That bust after two more years, but that was more to do with the big loads than anything else and a replacement insert solved the problem.

My main experience so far is with a Giant Twist power double I hired on holiday. That had a front hub motor with an 8 speed hub gear that was really easy to use and I am sure it must have had a torque sensor as it seemed like a normal bike to pedal to some extent. No throttle and I dont think I needed it.

I did think it needed an "overdrive" gear though, hence this post.

The downside to the Power Double was the weight especially at the back end with 2 batteries.

The guy we hired the bikes from claimed they weighed about 25 kg, maybe with extra for the batteries.

Lynda seems keen on the Tonaro, crank drive bike, that she has but some of these weigh in at 32kg gross, hard work if the battery goes flat. I think that would be a deal breaker for me.

 

Dave

My main experience so far is with a Giant Twist power double I hired on holiday. That had a front hub motor with an 8 speed hub gear that was really easy to use and I am sure it must have had a torque sensor as it seemed like a normal bike to pedal to some extent. No throttle and I dont think I needed it.

I did think it needed an "overdrive" gear though, hence this post.

 

Most e-bikes on the market suffer from the gearing biased on the low side with the top gear too low, seemingly matched to the 15 mph legal assist limit too much. Many change the chainwheel to lift the entire gear range, which is viable with 8 or more gears in most areas. Hub gear bikes can be simpler in this respect since a low cost change of just the rear sprocket can do the trick then.

"That bust after two more years, but that was more to do with the big loads than anything else"

 

Sorry I did not comment on your big load flecc. Dont you need a sign on the back and a land rover with a flashing light when you go on the road with that trailer. The panniers alone look heavy enough to cart around.

Most e-bikes on the market suffer from the gearing biased on the low side with the top gear too low, seemingly matched to the 15 mph legal assist limit too much.

 

... or just get a C11 .. top gears 8-11 are there for riding unassisted above 15mph easily on the flat and low gears are there for the steep hills when you really need 1-3. No compromising required.

Just a couple of points, my Tonaro Esprit weighs 4~5 kg less than your estimate.

 

Now to be controversial, if you are riding in hilly terrain and are looking at decent power level crank drive and can put in a decent amount of power yourself, I would not go with the 8 speed Shimano hub. It is brilliant at human power levels, smooth and accurate but at Tonaro plus rider power levels in steep terrain it feels like it is at its limit or beyond them, it will some times vibrate, click, not feel smooth, shifting points move etc. this is with a silky smooth cable etc. used at human power levels as stated above it is superb.

It does work really nicely most of the time and I am quite happy with it since I have stopped the torque twisting it out of position, but I do wonder how long it is going to last.

Sorry I did not comment on your big load flecc. Dont you need a sign on the back and a land rover with a flashing light when you go on the road with that trailer. The panniers alone look heavy enough to cart around.

 

Not as big as these panniers on my other bike though!

 

Loads 'R Us.

Dave Pat,

You have to understand that none of these gear systems was designed to take the power through them of crank drive plus rider power,but they were designed to take the power of a powerful rider and have some torque tolerance.

I have found for a hub drive bike the Shimano Nexus 8 hub system is excellent,also it is cheap and many are sold so spares are freely available. The additional power available with an ebike makes a gear setup above 8 speed an overkill,unless you intend to ride the bike unpowered a lot.

The power of these crank drive bikes plus a powerful rider may be too much for the Nexus 8,but I have, at this time ,no way of verifying that. Therefore the safe option seems to be derallieur gears-my personal favourite is the Deore 9 speed system but it is difficult to get delivery from Shimano at present.

Hope that helps

KudosDave

.................To help you judge, here's the gear range on the following hub gears:

 

Shimano Nexus 8 speed = 307%

 

NuVinci CVT = 350%

 

Shimano Nexus 11 speed hub = 409%

 

Rohloff Speedhub = 526%

 

As good as the Rohloff may be, I think it is overkill on an electric assisted bike.

 

Forgive , please, yet another dumb question from me.....but what are those percentages percentages of?

 

JimB

They are the span of the ratios Jim. For example, 307% just means the top gear is 3.07 times the lowest gear. Think of a simple derailleur system with one chainring, if that drives a low gear rear sprocket with 36 teeth and a high gear rear sprocket of 12 teeth, 12 into 36 goes 3 so that's 300%.

Thanks for that flecc. There is now just the faintest flicker of light from the bulb above my head:o

 

If one could assume (and I assume we can't) that in each case the middle gear of each unit (let's just assume that the ones with an even number of gears have a middle gear) resulted in the bike moving exactly the same distance per revolution of the pedal crank then all of the units quoted above share the ratios of the Nexus 8 speed which ranges 153.5% either side of it's middle gear and the Rohloff ranges 263% either side of it's middle gear. That's a huge difference.

 

The 11 speed Nexus at 204.5% range either side of middle gear still represents a very significant additional range below the Nexus 8s lowest gear and above it's top gear.

 

I can see how assistance from the motor will help negate the absence of the lower ratios on the 8 but due to the speed limiter operating will be of no help going down the other side when you might want to pedal up to speed to maximise use of the energy available (including gravity).

 

So, as I'm constantly being told, the best set up will definitely depend on how a user wants to use their bike. If, as I like to do upon reaching the top of a slope - put my feet up on the handle bars and coast down the other side enjoying the view I needn't worry about the lack of gears capable of propelling me to infinity and beyond.

 

Why does that NuVinci keeps beckoning to me?

 

Is it 'cos I'm just plain idle? Answers, on postcards please..........

 

Thanks, BTW, to Electrifying Cycles, for pointing me to this thread.

 

Thanks again,

 

JimB

Only the lowest and highest ratios that matter.

 

My favourite is Deore 10 speed cassette with 11T-36T on 700C wheels.

I can see how assistance from the motor will help negate the absence of the lower ratios on the 8 but due to the speed limiter operating will be of no help going down the other side when you might want to pedal up to speed to maximise use of the energy available (including gravity).

 

It's also about getting low enough in the lowest gears. Even the C11 is more useful at the very top than the very bottom of the range (but it's better than the C8 at both ends). Trouble is also that with crank drives motor isn't punchy enough in lowest gears. Powerful hub drive with throttle eliminates that but it feels as much like riding a scooter as riding a bike with the throttle down.

 

The high gears on C11 versus C8 were a must for me. I use them a lot riding >15mph and they're essential for pushing the bike to capitalize on slight to significant DH momentum.

 

There's so much less gear range on a CVT that my guess is it just wouldn't be any better than a C8 (save for allowing one to be lazy and not bother changing gear !).

Mine is a 9 speed, 11 - 34T. It's not the 36T that I miss, but a smaller disc at the other end.

The additional power available with an ebike makes a gear setup above 8 speed an overkill,unless you intend to ride the bike unpowered a lot.

KudosDave

 

Which is an important point if you want to 'bowl along' on the flat.

Mine is a 9 speed, 11 - 34T. It's not the 36T that I miss, but a smaller disc at the other end.

 

The trouble with sprockets smaller than 11 teeth is the high degree of wear they suffer, especially if spending most of the time using them such as in flattish country. It's annoying to have a whole cluster of sprockets compromised just because the smallest one is worn out while all the others are fine.

If one could assume (and I assume we can't) that in each case the middle gear of each unit (let's just assume that the ones with an even number of gears have a middle gear) resulted in the bike moving exactly the same distance per revolution of the pedal crank

 

As a matter of interest almost all hub gears including the NuVinci have a direct drive 1 to 1 gear roughly in the middle with reduction or increase to the gears either side. The exceptions are the Shimano Nexus 7 speed which has no direct drive, all 7 gears being indirect through the epicyclic gears, and the peculiar Sunrace-Sturmey 8 speed hub gear. The latter has the direct drive as the lowest "gear", with all the other 7 being above. The logic is that it makes the lowest gear for climbing the most efficient, but the downside is that the highest gear as the most commonly used is the least efficient.

I've found this to be very helpful and informative and realise that I've pretty much made the decision on which bike spec I would like for myself I'm still considering a second bike for my wife whose bike riding style and aspirations are a bit different to mine.

 

Whilst I love gadgets (including electronic ones) and am quite happy using the 24 gear set on my current bike she would be a lot happier not having to bother with them at all.

 

Manifold Valley and a couple of other test rides organised will hopefully help us finalise things.

 

JimB

For anyone interested in the comparative ratios and ranges of certain types of gear systems have a look at this PDF link I found on the Nuvinci website. Gear inches are still beyond my comprehension.

Sorry I dont know how to post the actual chart but maybe someone else can.

 

http://www.nuvinci.com/Docs/GearInchChart_N360.pdf

 

Dave

For anyone interested in the comparative ratios and ranges of certain types of gear systems have a look at this PDF link I found on the Nuvinci website. Gear inches are still beyond my comprehension.

Sorry I dont know how to post the actual chart but maybe someone else can.

 

http://www.nuvinci.com/Docs/GearInchChart_N360.pdf

 

Dave

 

Thanks for that, it highlights a bugbear I have with my 8-speed hub, the big gap when dropping from 6th to 5th, I'll try and get an 11-speed hub next I think.

Gear inches are still beyond my comprehension.

 

Dave

 

Gear inches first arrived with the original "penny-farthing" bike Dave. It was the diameter of the large wheel which, because the pedals and cranks were directly on that wheel, gave an indirect indication of how far the wheel would go for a single turn, though that needed to be multiplied by Pi (3.14) to give the actual number of inches travelled.

 

Of course that inch measure's real use was that it represented the gear ratio, since a larger wheel went further for a single pedal stroke than a smaller wheel, it was a higher gear and needed more effort than a smaller wheel turn.

 

When the "safety bicycle" (our modern type) was invented, the gear inches of the wheel needed to be multiplied by the up-gearing of the front to rear chain sprocket to give the same indication for comparison with the penny-farthings still in use. For example, if the bike had 25 inch wheels and the chainwheel had 45 teeth and the rear one 15 teeth, each turn of the pedals turned the wheel three times. Therefore the wheel diameter of 25" had to be multiplied by three to give the 75 inch gear that it had. In other words, it was like a penny-farthing with a 75 inch front wheel.

 

So to work out the gear inches on a particular gear of a derailleur bike, its just necessary to divide the chainwheel teeth by a particular rear sprocket number of teeth and multiply the result by the overall wheel diameter.

 

To do the same for a hub gear bike, one must first find the ratio comparisons of that hub gear. For example, the Nexus/Alfine 8 speed hub gears have these ratio steps up and down for the eight gears, fifth gear being direct drive:

 

1.615

1.419

1.223

1.000

0.851

0.748

0.622

0.527

 

To get the gear inches for a particular gear, just divide the chainwheel number of teeth by the rear sprocket number of teeth, multiply the result by the wheel overall diameter and then multiply that result by the ratio of the gear from that list for your hub gear.

 

For example, a Nexus 8 equipped 26" wheel bike with a 48 tooth chainwheel and 16 tooth rear sprocket would be this gear inch ratio in fourth gear:

 

48 divided by 16 = 3, then that 3 times the 26" wheel = 78, then that 78 times the 0.851 for the fourth gear = 66.378, a 66 inch gear.

.

Edited April 10, 201313 yr by flecc