getting the right gear

[geostorm]

has anyone converted Ezee to deuralier gears from hub, i suppose i would have to change chain and chainwheel, and of course i have hub brakes, maybe i should sell sprint and look at something else.

 

[Mussels]

It's quite a change and not necessarily better, what bike and hub are you starting with?

 

[Lloyd]

First thing to check is the rear drop out. Which model do you have? If it is a vertical dropout you will have a bolt on for the rear mech hanger to bolt to, if it's a horizontal drop out you won't have an attachment for a mech hanger, and therefor I wouldn't bother tbh.

 

[flecc]

You can get the Shimano add-on rear mechanism hanger pictured below to convert a hub gear frame for derailleur use and I've used one to add gears to a single speed rear motor e-bike.

However, for conversion from hub gear to derailleur I agree with Lloyd, not really worth it for the minimal benefits.

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[tangent]

I would be interested to know what people consider to be advantageous about derailleur gears on an e-bike. I would go for a quality internal hub any day, but have never properly tried out a quality derailleur so I may be missing something.

 

[Mussels]

I would be interested to know what people consider to be advantageous about derailleur gears on an e-bike. I would go for a quality internal hub any day, but have never properly tried out a quality derailleur so I may be missing something.

I've had both and neither was perfect.
The derailers were high maintenance and with a single chainring didn't have a big enough range for a hilly area.
The Alfine hub is better than most as I don't have to stop pedalling whilst changing gear and the range is good. Unfortunately the gaps between gears are too big and I can't keep the right cadence, I didn't think it would cause me a problem but it has and I've had to ease off the pace when I don't want to.
Hub gears are good for a low maintenance utility bike and suit my commuting ebike well (apart from the cadence issue) but there's no way I'd currently have them on my road bike. If they had more, closer spaced gears then I might change my mind but not yet.

 

[andrewgardner]

I would be interested to know what people consider to be advantageous about derailleur gears on an e-bike. I would go for a quality internal hub any day, but have never properly tried out a quality derailleur so I may be missing something.

The advantage of derailleur gears for me is that I can have close ratios, ok I had to buy two cassettes 12/28 and 11/28 split them and build one which is 11,12,13,14,15,18, 21.
I have tripple chainrings,(28/38/48) and can peddle up to 28mph without spinning out with my 11/48 (its a 27" wheel) and have never had to get off and push with my 21/28.

It is just a lot more smooooth with close ratios.

 

[flecc]

Faster gear changing, closer ratios and higher efficiency possible with derailleurs.

Long life and low maintenance from hub gears, which are catching up on gear change speed but not on efficiency*.

In brief, a sport or utility choice.

* Please, no quoting manufacturer's efficiency figures for hub gears, they are bunkum.
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[Mussels]

Faster gear changing, closer ratios and higher efficiency possible with derailleurs.

I'm not so sure about faster gear changing, the Alfine seems quicker than the Deore mech on my 905.
The ratios are the only thing I don't like but that's quite a big thing.

Another advantage of hub gears is they are good off road with less dangly bits to get caught in the undergrowth.

 

[JamesC]

I'm not so sure about faster gear changing, the Alfine seems quicker than the Deore mech on my 905.
The ratios are the only thing I don't like but that's quite a big thing.

Another advantage of hub gears is they are good off road with less dangly bits to get caught in the undergrowth.

The Alfine will be particularly quick with the motor being in the front wheel.

Hub gears have been more commonly associated with the panasonic style of drive where the motor applies its drive force onto the chain to assist the effort of the rider.

The rider pauses on the pedals for the gearchange, but the motor pulls for another couple of seconds, requiring a slightly slower gearchange to let the load off the hub gear.

I am using a Rohloff hub gear at present on the ProConnect - the close ratios and the extended gear range are excellent, but it requires a longer pause for the motor to die down than with the Shimano.

This does not cause a problem when touring, but might frustrate when darting through traffic on a commute.

James

 

[tangent]

Interesting comments everyone. I had not thought much about gear spacing and would be interested to know more about gear efficiency. Naively, I really did believe the manufacturer's numbers!

With hub gears I really value the ability to change down while stationary or not pedalling.

 

[flecc]

And the Alfine is an exception, in general hub gears are slower changing. An SRAM P5 or S7 takes forever!
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[Mussels]

Interesting comments everyone. I had not thought much about gear spacing and would be interested to know more about gear efficiency. Naively, I really did believe the manufacturer's numbers!

I don't doubt they are inefficient but I can't say I've noticed the difference on a pedelec. There will be one gear that is a direct connection and as efficient as derailers, this is usually the gear you cruise in and has been set up like that on my 906.

With hub gears I really value the ability to change down while stationary or not pedalling.

I thought this would be important and it is nice but I don't ever remember being stopped in the wrong gear when I had the 905, it's easy to plan ahead.

 

[flecc]

I don't doubt they are inefficient but I can't say I've noticed the difference on a pedelec. There will be one gear that is a direct connection and as efficient as derailers, this is usually the gear you cruise in and has been set up like that on my 906.

Direct drive is usually the gear nearest the middle and always so on Shimano hubs. Bikes are usually set up for cruising in higher gears or top gear where the inefficiency is much greater, and that's essential with chain drive bikes if they are to be legal.

Derailleurs are much more efficient, typically 97 to 99% if in good condition, and contrary to popular belief, the chain running out of line in some gears has a minimal effect.

Hub gear efficiencies vary from 100% in the direct drive gear down to as low as 84% at the gearing extremes. They are reported as an average of the efficiencies in each gear including the 100% direct gear, so a 3 speed hub benefits much more from that than an 8 speed.

Manufacturer's figures are rubbish, independent tests much more reliable though not always so. The highest independent average seen from one tester is 91% for a 3 speed SRAM hub, but other independents have disputed that and criticised some aspects of the testing. You can safely assume at least 10% lower efficiency than derailleurs from most hub gears.

One problem is that hub gears use epicyclic gears which, using three cogs as they do for each power transfer, as much as triple the losses of a single engagement. In addition, these cogs are small diameter so the tooth engagement approach angle is greater and so generates higher friction. Worse still, to generate more gears from fewer epicyclics, they use them in combinations to achieve all the ratios, so at each combination the losses are doubled by the compounding.

Since these losses grow with greater gear range, newer hubs with 8 or more gears are made larger diameter to enable larger cogs and keep losses within bounds, Shimano's 8 speed hubs and SRAM's 9 speed i-motion hub being examples of this.

The direct drive gear position varies, Shimano and SRAM hubs near the middle excepting the Shimano 7 speed which has no direct drive, all being indirect. The Sunrace-Sturmey 8 speed has direct drive on bottom gear, so has to use small chainwheels and larger rear sprockets to keep the gear ratio increase with changes up within bounds.
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