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Old 01-30-06, 07:01 AM   #1
highlyselassie
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Why no affordable mtb internal gear hub?

Seems to be an untapped market.

I understand Sram and Shimano don't recommend their internal gear hubs for off-road use, but the question is, what about them is not off-road worthy?. What would they need to improve upon to make these hubs sturdy enough for heavy mtb use?

Could the reason behind them not developing/marketing a mtb internal gear hub be they don't want it to clash with their lucrative derailleur based groupsets?
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Old 01-30-06, 01:49 PM   #2
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Maybe someone should build one up and try it. I don't do so much mtb, but I might consider using one of my spare nexus-7 internals next time I build one up --just for grins.

I use them for kids bikes (even adult sized teenage kids) because I got tired of pulling rear derailers out of the rear spokes. My experience has been good. They stand up to kid abuse just fine.
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Old 01-30-06, 01:58 PM   #3
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Quote:
Originally Posted by highlyselassie
what about them is not off-road worthy?.
the Shimano and Sram cannot be used with a disc brake- that is the main problem for me - I have thought about buying an internal hub for a winter bike but the Rohloff is too expensive and I won“t give up my disc brakes

there is definitely an untapped market though you are right
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Old 01-30-06, 02:00 PM   #4
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I'd go for it, for sure. Do they really not recommend the existing hubs for off-road? What is the official reason?
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Old 01-30-06, 02:14 PM   #5
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Quote:
Originally Posted by highlyselassie
Seems to be an untapped market.

I understand Sram and Shimano don't recommend their internal gear hubs for off-road use, but the question is, what about them is not off-road worthy?. What would they need to improve upon to make these hubs sturdy enough for heavy mtb use?

Could the reason behind them not developing/marketing a mtb internal gear hub be they don't want it to clash with their lucrative derailleur based groupsets?
Sram and Shimano gearhubs as currently offered are unsuitable for MTB use. Don't get me wrong here, I am a big fan of both these units, but only for their intended purpose , that being commuting or bike path use. They are even OK for touring as long as the route is fairly level, and you are not hauling big packs. For one thing, the ratio coverage, at something in the 300% range is seriously inadequate for off road use. Also, gear changing requires a break in pedalling torque, and sometimes even a slight back pedal to make a shift. Do you want to have to cope with that on a technical trail?
Furthermore, the internals are just not up to that kind of punishment. They are not terribly delicate, but having been up close and personal with the interior of the Sram unit at least, I just don't think it is rugged enough for that kind of use.
Now, I am assuming because you used the word "affordable" in your title, you have ruled out the Rohloff Speedhub. This is the one truly off-road capable gear hub. I have one of these as well, and I can tell you that I prefer it to the XT/XTR drive train I replaced with it. Sure it's pricey, but if it lasts as advertized, it will pay for it's self.
There is one other newer option out there, but I know nothing about it. It is the Nupace continuously variable hub. You can check it out here.
http://www.freeridehubs.com/
You will find some negative stuff about Rohloff on that site, but I would advise against taking it too seriously.
Dan
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Old 01-30-06, 06:15 PM   #6
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the Shimano and Sram cannot be used with a disc brake- that is the main problem for me - I have thought about buying an internal hub for a winter bike but the Rohloff is too expensive and I won“t give up my disc brakes
I can understand the appeal of a disc brake on the front wheel, but why do you need one on the rear?. Even when the braking surface is covered in all kinds of muck, I can still lock the rear wheel with almost any half decent v-brake.

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For one thing, the ratio coverage, at something in the 300% range is seriously inadequate for off road use
Couldn't you just gear it low enough that you spin more on descents, I'm sure that would leave you with a fair amount of range for the uphills. 300% range is still 300% more than singlespeed/fixed mtb'ers have and they seem to enjoy themselves well enough, there's no shame in dismounting every once in a while, is there?

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Also, gear changing requires a break in pedalling torque, and sometimes even a slight back pedal to make a shift. Do you want to have to cope with that on a technical trail?
I was under the impression you could shift whilst pedalling with the Shimano units(not stomping, just slight pressure). At any rate, don't you have to ease off the torque when changing up/down with derailleur gears aswell.

Back pedalling to make a shift would be highly annoying, yes. Any idea why you sometimes need to do so to make a shift?(is this Shimano and/or Sram hub you're commenting on?)

Quote:
Now, I am assuming because you used the word "affordable" in your title, you have ruled out the Rohloff Speedhub. This is the one truly off-road capable gear hub. I have one of these as well, and I can tell you that I prefer it to the XT/XTR drive train I replaced with it. Sure it's pricey, but if it lasts as advertized, it will pay for it's self.
I have no problem with the Rohloff hub, I'm sure it's a fantastic bit of kit,but...

it is very expensive!

and whilst it'll certainly outlast many a XT drivetrain, it's yet to prove itself fully, durability wise, against the likes of Sturmey-Archer hubs. SA hubs generally cost about 1/6 the price of a Rohloff, the point being does it really need to take all that extra expenditure on the consumers part to get an "off-road" worthy hub, are the problems that are preventing the SA/Sram/Shimano hubs from being off-roadable hubs really that expensive to fix?
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Old 01-30-06, 06:17 PM   #7
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Now to build an ISO brake adapter for a Nexus hub! who is up for the challenge
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Old 01-30-06, 07:03 PM   #8
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Quote:
Originally Posted by highlyselassie
I can understand the appeal of a disc brake on the front wheel, but why do you need one on the rear?. Even when the braking surface is covered in all kinds of muck, I can still lock the rear wheel with almost any half decent v-brake.
In freezing temps rim brakes can become worthless. I have had my brake surface covered in ice after riding though water. I was unable to lock up the brakes even when my tire was on a patch of ice.
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Old 01-30-06, 10:26 PM   #9
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The reason you can't use those hubs off road is the huge amount of torque low mtb gearing will put on them........it will explode (or possibly implode). If you have skinny girl legs and/or walk up any steep climb then it will probably last. But if you want a usable low gear of 17" like your 22x34 gives you, you will break the hub. Unless it is made by Rohloff.

This is in addition to everything that Mr Burkhart said, and he appeared to know what he was talking about. If you refuse to beleive us by all means try it out and let us know how it goes!

Andrew

BTW just checked shimano's site and crunched some numbers......to get a 17" low gear on a nexus 7 with a 16t cog would require a 15t chainring! Ha! Just spin a little faster on the downhills..........
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Old 01-31-06, 03:48 AM   #10
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In freezing temps rim brakes can become worthless. I have had my brake surface covered in ice after riding though water. I was unable to lock up the brakes even when my tire was on a patch of ice.
Yeah?

It never really gets quite that cold round here, so I can't say it's something I've personally experienced. Definitely something to keep in mind though

Quote:
This is in addition to everything that Mr Burkhart said, and he appeared to know what he was talking about. If you refuse to beleive us by all means try it out and let us know how it goes!
Why so defensive?

Am I out of order by asking these questions?

Like I said previously, I've no doubt the SA/Sram/Shimano hubs have problems, but whether it really needs to take an extra £500/£600 to attain an off-road worthy hub is questionable and something that should be questioned...

Rohloff currently have the run of the market, so it's pretty logical that they can charge whatever they like.
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Old 01-31-06, 04:23 AM   #11
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G-Boxx. http://www.nicolai.net/
Internal 24speed gearboxx.
Affordable.....no.

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Old 01-31-06, 05:45 AM   #12
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Only now I am building a mtb with an internal geared hub. For several years I abuse internal gear hubs and I am still to find the sort of bicycle riding style they will not fit. German manufacturers are building DH and freeride bicycles with internal gear hubs and I am wondering why ?! An internal gear hub can be shifted when ever the rider wants, even in effort and I dought the strongest of the riders during the hardest of effort will damage such hubs. Try a Nexus 8 with a 22 teeth cog and an ordinary crank with 44, 32, 22 chain rings and you will see your bicycle climbing walls! If you do not believe me, read Sheldon Brown's articles on internal geared hubs or send him an E.mail on the issue and then make your conclusions.
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Old 01-31-06, 10:58 AM   #13
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I have no idea of the quality, but a company called Dynamic Bicycles is marketing a couple of Mountain Bikes with Nexus 8 speed hubs and shaft drive. Interesting concept.
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Old 01-31-06, 02:56 PM   #14
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Try a Nexus 8 with a 22 teeth cog and an ordinary crank with 44, 32, 22 chain rings and you will see your bicycle climbing walls!
Cool idea, but don't you have trouble keeping a straight enough chainline with 3 chainrings?

One method I think would work really well is to have two sprockets on the hub, one about twice the size of the other[say a 11/22 or 12/24] and a rear derailleur to shift between them. This should double the gear range with very little overlap, the rear derailleur will keep a good chainline and I don't think it'll add too much to the maintenance needed.

What'd you lot think?
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Old 01-31-06, 03:23 PM   #15
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The Rohloff hub has a lower gearing limit set to 2.4:1. That means your lowest possible gearing is a 15T sprocket with a 36T chain ring. Go below that, and you void the warranty, and you risk wearing it out much faster, I assume.
That combo gives you a range from a low of 17 gear inches to a high of 90 gear inches.
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Old 01-31-06, 03:52 PM   #16
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The setup i wrote about below was aimed at the SA/Shimano/Sram hubs, which sprockets from 14t to 24t are available for. Such a setup for the Rohloff hub would just be unnecessary complication and you can only get sprockets from 15t to 19t anyway(correct?).
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Old 01-31-06, 03:54 PM   #17
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I meant above, even
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Old 01-31-06, 04:29 PM   #18
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My post wasn't really in response to your last one, just a reply to the thread in general.
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Old 01-31-06, 04:49 PM   #19
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No probs, do you have a Rohloff equipped bike?.
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Old 01-31-06, 04:55 PM   #20
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Nope. Nothing for me, that. I have regular derailer gearing.
Would be fun for a pure inner-city commuter bike, but not for anything else.
And my entire bike doesn't cost as much as the Rohloff by itself...
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Old 01-31-06, 05:05 PM   #21
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You'd stick a Rohloff on a commuter, you must 'ave a screw loose, mate
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Old 01-31-06, 08:22 PM   #22
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Quote:
Originally Posted by royalflash
the Shimano and Sram cannot be used with a disc brake
I give up. How does the geared hub know what mechanical mechanism is being used to slow the wheel?
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Old 01-31-06, 08:36 PM   #23
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I give up. How does the geared hub know what mechanical mechanism is being used to slow the wheel?
The hubs are made without any place to attach a brake disc.
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Old 01-31-06, 10:32 PM   #24
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If you do try and build a MTB with an internal gear hub, go with the Shimano. While the SRAM hubs work great, the way the shift cable attaches to the hub is through the end of the hub. A small chain screws into the end and is fed through a plastic pulley kind of deal that can break quite easily if hit against something, which can happen alot since it sticks straight out of the end of the nut holding the hub in place. The Shimano nexus does not have this problem. BTW, just wondering if any of the people trashing this idea had ever ridden for a long period of time on an internal gear hub, or if they actually know anyone who has. Even LBS's tend to have misinformation on them...my 2 cents
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Old 01-31-06, 11:29 PM   #25
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For those of you missing the disc brake capability, why not go for an internal gear hub with drum brake. Not quite a disc, and somewhat heavier. You can still have a disc on the front, where it really matters.
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