Author Topic: Four gears in hub.  (Read 9671 times)

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Offline Westinghouse

Four gears in hub.
« on: February 27, 2009, 07:39:22 am »
I have heard about rear wheels with four or more gears inside the hub. I imagine such wheels would not be dished. Can such a wheel be used with a triple chain set on the front? The three speed hubs have been around forever. I had a Raleigh with a three speed hub when I was  a kid. Are there hubs with more than four speeds?

Does anyone know of any particular advantages or disadvantages to using an internally geared wheel?

Online staehpj1

Re: Four gears in hub.
« Reply #1 on: February 27, 2009, 07:51:49 am »
Check out the Rohloff (14 speeds and $$$).  I am not a fan for my use, but some swear by them.  They are often used for expedition type tours and off road.
http://www.sheldonbrown.com/harris/rohloff.html
http://en.wikipedia.org/wiki/Rohloff_Speedhub
http://www.sjscycles.co.uk/product.asp?pf_id=11229&src=froogleUS&currency=USD

Also look at the cheaper shimano-nexus 8 speed.
http://www.sheldonbrown.com/harris/shimano-nexus.html

For using a triple on front, yes it is possible if you use the right type of chain tensioner.  Dig around on the sheldon brown site a bit.  I saw something there.

Also you could use a schlumpf speed drive.  I think it is also expensive.
http://schlumpf.ch/sd_engl.htm
« Last Edit: February 27, 2009, 07:57:46 am by staehpj1 »

Offline RussSeaton

Re: Four gears in hub.
« Reply #2 on: February 27, 2009, 09:21:32 am »
SRAM, formerly Sachs, also makes internal gear rear hubs.  Yes you can combine them with a multi ring crankset and front derailleur.  Recumbent tandems frequently use a SRAM/Sachs rear hub and triple crankset.  Chain tensioning would be accomplished with the second link.  As you state wheel strength should be good.  More gears over a wider range is a benefit.  Thus their use on tandem recumbents.  Upright bike would have no need for this though.  Disadvantage is cost and complexity.

http://www.sram-imotion.com/us/html/navigation_us.html

http://www.excelsports.com/new.asp?page=8&description=Singleator+Chain+Tensioner&vendorCode=Surly&major=10&minor=6

Offline RussSeaton

Re: Four gears in hub.
« Reply #3 on: February 27, 2009, 02:26:50 pm »
Recumbent tandems frequently use a SRAM/Sachs rear hub and triple crankset. 

The recumbent tandem I am speaking of would use a triple crankset, the rear internal hub gear, 3 speed most likely, and a 7-8-9 cassette.  60 to 90 gears, lots of overlap.

Offline whittierider

Re: Four gears in hub.
« Reply #4 on: February 27, 2009, 02:59:58 pm »
Quote
Disadvantage is cost and complexity
plus, they're very heavy and they are not as efficient.  A chain drive in good condition wastes only 2% of your power.  The geared hub itself wastes about twice as much, and then you still have the chain.  One novelty someone is selling is a geared hub with an enclosed shaft drive so there's no chain at all.  It would have an advantage if you ride in rain all the time, but the shaft with its bevel gears at each end wastes more than the chain too; so altogether you lose close to 10% of your power.  The larger jumps between gears (13.6% for the Rohloff 14-speed, and 13-17% for the Shimano 7-speed) would be undesirable to some, although not much of a problem for touring.

I can't think of any advantage to having multiple chainrings and cassette and internally geared hub.

Offline RussSeaton

Re: Four gears in hub.
« Reply #5 on: February 27, 2009, 04:52:52 pm »
I can't think of any advantage to having multiple chainrings and cassette and internally geared hub.

Unbelievable range of gears.  For the recumbent tandem I mentioned that does come with all three, it needs super duper low to get up the hill.  And can utilize super high going down.  For a single bike, no need at all.

Offline TCS

Re: Four gears in hub.
« Reply #6 on: February 27, 2009, 08:43:04 pm »
Sturmey-Archer introduced their 4-speed hub in the late 1930s, when it was given a special award by the CTC as a significant advancement for touring cyclists.  A rider named Tommy Godwin used a Sturmey-Archer four-speed  hub to set the unsurpassed all-time single year mileage record of 75,065 miles (1939).

A small number of the original Bike Centennial riders crossed the country in 1976 using three- and four-speed hub gears.  Modern internal gear hub bikes have come a long way since then, and today one can acquire hubs with 2, 3, 4, 5, 7, 8, 9, 12 and 14 gears built by Rohloff, Shimano, SRAM (Sachs) and SunRace Sturmey-Acher.

Fun facts:  Sturmey has been building internal hub gears since 1903, Sachs since 1904.  Shimano started manufacturing internal hub gears in 1957, and the first Shimano component sold in the USA was their 3 speed hub (1961).

There is much conventional "wisdom" and old wives' tales about the inefficiency of internal hub gears.  The best science on the subject (the Kyle/Berto tests) actually found that the efficiency of derailleur and hub gears overlap in the same range (84~98%).

Best,
tcs
"My name is Pither.  I am at present on a cycling tour of the North Cornwall area taking in Bude and..."

Offline DaveB

Re: Four gears in hub.
« Reply #7 on: February 27, 2009, 08:46:24 pm »
.  One novelty someone is selling is a geared hub with an enclosed shaft drive so there's no chain at all.  It would have an advantage if you ride in rain all the time, but the shaft with its bevel gears at each end wastes more than the chain too; so altogether you lose close to 10% of your power. 
Dynamic Bicycles (http://www.dynamicbicycles.com/) makes shaft drive bikes with 7 and 8-speed internally geared hubs.  I got the chance to ride one a few months ago and the feeling of "drag" compared to a derailleur bike was very obvious.  For low maintenance these are unequaled but the efficiency loss is dramatic.

Offline DaveB

Re: Four gears in hub.
« Reply #8 on: February 27, 2009, 08:49:08 pm »
There is much conventional "wisdom" and old wives' tales about the inefficiency of internal hub gears.  The best science on the subject (the Kyle/Berto tests) actually found that the efficiency of derailleur and hub gears overlap in the same range (84~98%).
The range of 84% to 98% is huge.  It is not a trivial difference.

Offline whittierider

Re: Four gears in hub.
« Reply #9 on: February 27, 2009, 10:20:36 pm »
Quote
There is much conventional "wisdom" and old wives' tales about the inefficiency of internal hub gears.  The best science on the subject (the Kyle/Berto tests) actually found that the efficiency of derailleur and hub gears overlap in the same range (84~98%).

According to the test results given in Bicycling magazine a few years ago, only the rusty, unlubed chains were in the lower part of that range, and a healthy chain drive was at 98%.  Rohloff's own website says their 14-speed hub is only 96% efficient in gears 1 through 7, which puts it on par with manual automobile transmissions; but the fact remains that with the geared hub, you have the losses of both the hub and the chain, so you're at 94% max in those gears-- and then you still have the big jumps between gears, reducing the efficiency of the human engine as well.  I look forward to seeing more relevant test data, but it looks rather impossible for the geared hub to compete in efficiency.  Weight and cost are yet another matter.  I doubt there's anything keeping them from making shifters that are operated the same as others in the industry, but I myself definitely don't want a twist-grip shifter.  And although I haven't seen enough info, I also suspect fixing a flat takes longer.

There is experimentation with belt drives, but according to someone who has tried it, they have a long way to go before becoming a viable product.  According to wikipedia, belt efficiency is typically about 95% and can be as high as 98% only with a chevron-toothed synchronous belt.  Shifting with the belt is quite impractical though.

Offline Westinghouse

Re: Four gears in hub.
« Reply #10 on: February 28, 2009, 02:51:04 am »
All right. Thanks very much. I was not very well aware of all these new developments in hub-geared bikes. There does seem to be some conflicting information regarding power transmission efficiency. The way I see that sort of thing is this. If I can actually feel that negative difference in efficiency, there is  difference enough to consider not using the wheel. I would be willing to pay a bit extra, and do with some negligible decrease in pedaling efficiency if it meant far fewer or no more broken spokes on the freewheel side. I am going to have to tie in to those web sites and do more reading on the subject, which I definitely will do.

Offline whittierider

Re: Four gears in hub.
« Reply #11 on: February 28, 2009, 04:48:55 am »

Quote
if it meant far fewer or no more broken spokes on the freewheel side.

To get a symetrical (dishless) wheel, just use a rim with the holes off-center, like the Velocity Aerohead O/C:



Then the spokes on the two sides have the same bracing angle and tension.  If you have Peter White (see http://www.peterwhitecycles.com/wheels.asp ) build it, it will have a lifetime warranty on anything having to do with build quality.  I found out about him from all the people on the tandem forum raving about his ultra-dependable wheels, and so far we've had him build us six wheels (including three rear wheels).  I can tell you we haven't had a speck of trouble with any of them, but that's not saying much when you're only a couple of years into a lifetime warranty.

Offline DU

Re: Four gears in hub.
« Reply #12 on: February 28, 2009, 09:37:54 am »
The tandem wheels I have are dishless due to the spacing of the rear dropouts being 145mm. Co-Motion builds their touring bikes with this spacing so they will have dishless rear wheels. I don't have a Co-Motion but my touring bike has this spacing and I have never had a spoke issue.

Offline Tourista829

Re: Four gears in hub.
« Reply #13 on: February 28, 2009, 11:08:25 am »
I suppose I should get my 2 cents in. I own a 2003 Breezer Uptown with a 7 speed Shimano Nexus rear hub. There are thee advantages I like when using this arrangement and three disadvantages. I wonder how many people who responded actually owned or ridden a bike with an internal hub with more than three speeds? I dare say very few.

Advantages
1.  When you stop suddenly and may be in the wrong gear, you can switch to any gear while at rest.
2.  They are very sturdy, usually sealed and require very little maintainence. (I also have an older Kholoff folding
     bike with a Sturmey Archer 3 speed hub which does require a little oil put in an oil port, very cool.)
3.  Grip shift, which may be as much of a disadvantage depending on your point of view. It never bothered me.

Disadvantages
1. Better know how to set up after you change a rear flat tire. There is a cable than may become lose.
    Must line up the two red marks on the gear. Or you won't be able to shift properly.
2. Other than the Rohloff 14 speed ($1100+) and has it's own quirks, although they may have been addressed, is
    not designed for big hills. I have a 16 tooth gear which on a 7 speed equates to approximately 37" low gear and
    86" high gear. Maybe if I went to a larger tooth gear I would be able to climb better but I would sacrifice more
    top end. I think the Nexius 8 range is 31" to 93" a little better. (It is approx since I haven't used the late great
    Sheldon Brown's internal hub gear calcuator recently)
3. As  stated in another post, there are big gaps in gear range although I know the Nexius 8 speed has helped
   addressed some of this.

The only bike I have ever ridden that had 24 gear with a rear internal hub, was made by Cannondale a few years back. It was on there top end Adventure Hybrid. If I am not mistaken I believe it may have had a rear derailleur and internal hub, which was odd in itself. It rode pretty well. If interested, you could write to Cannondale and ask them. I also think Giant with their Transend EX may have a similar arrangement.

For short errands and commuting I like this arrangement. Any serious touring or distances and I would go with a 9 speed rear derailleur and 3 speed crank or you could spend a bundle and go with the Rohloff. That's more like two bits than two cents.

Offline DaveB

Re: Four gears in hub.
« Reply #14 on: February 28, 2009, 11:23:27 am »
I would be willing to pay a bit extra, and do with some negligible decrease in pedaling efficiency if it meant far fewer or no more broken spokes on the freewheel side. I am going to have to tie in to those web sites and do more reading on the subject, which I definitely will do.
Do you have a problem with broken spokes or are just concerned about the possibility?  Decades ago, in the days of plated or galvanized steel spokes, broken spokes were fairly common.  Now with stainless steel spokes and a proper wheel build, broken spokes are very rare, even with 32 spoke wheels and fairly heavy riders. 

The broke spokes I've ever encounter were on the rear wheel of an '85 Bridgestone 400.  The wheels were 36H, 27" Arya rims with 14 ga straight cadmium plated spokes laced 4X.  I.e. in concept, a very rugged build.  They began to break on the drive side at about 8500 miles.  Now, the factory tension may have been inadequate too which can be a major contributor. 

Since then I've had wheels with DT or Wheelsmith 14 ga., 14/15/14 db or 14/17/14 db stainless steel spokes, all 32H, laced 3x in 27", 700c and 26" and NEVER broken a spoke on any of them in over 120,000 miles of riding.  Several of these wheels had 30,000 miles on them when they were replaced due to rim cracking at the brake track or the rim getting too thin from brake wear to trust. My riding includes some pretty rough roads too so these wheels were never babied.

The point of this is to ask if you are over reacting to the possibility of broken spokes or really have a problem with them.  Properly built and tensioned wheels with modern spokes should be very durable and reliable.