MrInitialMan

As I've mentioned over in the Framebuilder's forum, I'm working on a large velomobile. But I was warned that an IGH might not stand up to the strain of ~500+ lbs.

HerrKaLeun

You mean you produce 500 pounds of thrust? Imagine a 500 pound bike and you lift it vertically.... is that how much force you apply to your bike?

MrInitialMan

I'm talking about the combined weight of my body and my 'cycle, but I think I see what you mean. Unless I misunderstand, you're saying that it doesn't matter how much my 'cycle and I weigh together, what matters is what my legs can give.

Am I correct?

HerrKaLeun

correct. If your trailer and bike and yourself weigh 500 pounds you only go at 5 mph up a hill. If it weighs only 200 pounds, it goes up at 12 mph. Same power input with the same legs.

Shimagnolo

A few years ago, I read a posting here by a guy who had been experimenting with a homebuilt electric-assist bike. He had trashed a number of different IGH's and to my surprise, the only one he found that would hold up to the combined force of human + electric-motor was the NuVinci.

Andrew R Stewart 

Back in the day of birthing mountain bikes some tried IGHs (Shimano 333 and SA AW I believe). The internals didn't keep up to the loads and shocks that off road riding dealt out. I suspect today's newer IGHs are stronger, but by how much? IIRC Shimano has stated their hubs lowest gear allowed. Andy

MrInitialMan

Interesting. Electric-Motor wouldn't be a concern here--Motor + (4 wheels) + (Canadian Law) = (Can Of Worms)^(DO NOT OPEN!)

Also, the worst this is going to be ridden over is gravel roads.

stevoo

At work some of the Worksman brand trikes had them. Some lasted for a while, some blew up rather quickly. Ended up using only single gear hubs eventually.
The shop guys (heavy equip mfg) tend to be hard on things.
I had to rebuild many of those wheels and weld frames back together.
Take it for what it is worth.

tcarl

I was considering using a Sturmey Archer hub for loaded touring, but somewhere in all their technical documents I saw it written that this hub was not to be used on tandems or mountains bikes, but "for normal use only." I sent an email to SA and specifically asked for their thought - they recommended against it. Also in researching all this I found some reviewers who's experiences were that, at least with the hubs they saw, the internal gear hubs didn't last very long in high torque situations.

Racing Dan

Nuvinci has a commercial rated model for rental bikes. Maybe that is wort a look. Im sure though, that a 8-10 speed mtb derailleur gear would be more reliable, cheaper and provide an adequate gear range. Loooow gears are needed if the total wight is 500 lbs.

Racing Dan

Imo, not correct.

If your bike is 500 lbs you need very low gears to get it up to speed and up the hills, but most IGHs are limited to how low a gearing you can use, to limit torque. As far as I can tell, the only way to overcome this limitation in IGHs is to have a small 16-20" driving wheel. That way you can have a super low final gear ratio without over torquing the gear mechanism.

MrInitialMan

Well, if I find out what I hope to hear, I'll be using TWO IGH's.

Dan Burkhart 

In series or parallel? If the torque is divided, the chances of durability are greater.

rydabent

Do any IGH mfg publish torque ratings for their hubs.

MrInitialMan

Series, allowing for a lower gear. Though isn't there Internal Gear pedals?

Retro Grouch 

I have a personal friend who owned a Bike Friday triple with an IGH hub. I'm sure that the three of them combined weighed more than 500 pounds and produced a good amount of torque. They never had any problems that I'm aware of with the IGH hub but I had to rebuild their wheel with fewer crosses to stop breaking spokes at the nipple.

fietsbob

I saw online, that in Berlin they have made a portable stage to move a concert grand piano around the city. (Busking?)

Powered by 3 pedalers with Rohloff hubs , there are also several other axles on more wheels to share the load,
but 3 people will move it around the streets..

so if in doubt add more wheels but not all have to be driven.. more like front wheels..





...

fietsbob

Yes, there are crankset gear boxes , also , the most complex also German is the Pinion.. 18 speeds , like a Motorcycle transmission..

there are a few 2 speed planetary geared cranksets, I own one, made in Switzerland..

and new the Efneo , also from Europe, with 3 speeds..




....

2manybikes

somewhere? I read that there were limits to how low you can go on chain ring teeth, for some Shimano IGH. Can't find it right now. Sheldon Brown I think damaged a few IGHs with too small a chainring. The smaller the ring the more torque you can put on the hub. That's why it is easier to pedal. Better leverage.

fietsbob

... and the smaller the wheel all else in the gear ratios, remaining the same, will be geared lower..

2 Rohloffs , both a 16t cog , the 26" wheel has a 38t, the 20" a 53t,, the over the road gear range is about the same .

Smaller wheels can be stronger, as well .





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2manybikes

True, but the limit of the force on the hub is what the hub manufacturer is concerned with.....

Copied from Sheldons pages about the Rolhoff hubs...

Notes on the Rohloff gear chart.
The 3 red highlighted possibilities are to be used at the owner’s own risk.
Rohloff will not give a warranty on the hubs when a gear with an input ratio smaller than 38 x 16 (2.375:1) is used. This (38 x 16) ratio is permissible for use by world class athletes (permissible even for 2 athletes, on tandem)
The diameter the wheel and the gear ratio produced are not relevant…it is the input ratio which is critical…Rohloff state 150 kg pedal force (!!!) with 170 mm cranks as max. input, if exceeded, this could damage the hub as easily in 14th as it could in 1st
In our opinion 38 x 16 is an ideal general touring gear, some may say it is too low, but if you are fit enough, or can get fit enough to spin 14th gear at a knee-saving 100rpm for 1 hour you would travel 43.377 km (27.11 miles) on 26” wheels!

fietsbob

Rohloff is 10 reduction gears 1~7 are compound reduction gears , only 3 are overdrive gears..
a 38:16 in a 20"... (2.375:1) x 20 *, rather than (2.375:1) x 26, your nominal wheel diameter.

Sturmey Archer 8 speed is all overdrive gears, 1 is is 1:1 their new 4 speed , likewise
S-A AW3 is a .75 reduction gear, and a 1.33 over drive 3/4 & 4/3..

the 7 speeds in a Rohloff is like 3 3 speeds, 9 minus the other 2 redundant 1:1. that's 11th..

the lowest gear in high range , is followed by the highest gear in low range, the 8th to 7th gear change is a double shift..


Yes, you can RTFM, Rohloff has it in PDF , online. I have mine in print , a copy in German and another in English...

* the bigger the chainring the less torque load in the lower range than a smaller chainring in a bigger wheel ..

that in the manual printed by the manufacturer.. they did further studies (after Sheldon died, so he missed the update)

modifying the recommendations, for the new 29er plus bikes , that have even bigger wheels..







....

Racing Dan

Of course the wheel diameter matters. 1/2 the diameter will produce 1/2 the torque for the same power, because the wheel spins at 2x the rpm.

79pmooney

Series means the second IGH is seeing far higher chain loads than they are intended to handle. I'll bet it has a very short life if you do any real hills.

Ben

2manybikes

That was my initial thought too. But for some reason Roloff says it does not matter. I just copied their text and pasted it in my post. I have seen something similar in a Shimano Sales and service book.

Maybe it's something needed to cover one's -ss. In case of warranty problems. Possibly if one is using a small wheel if there is enough weight on the bike there still is a lot of torque to get going. Like a morbidly obese rider and lots of touring equipment. Starting up a hill.