Anthony DeLorenzo said:
I'm really keen to use an internally-geared hub on a touring bike I am
building up. I like (need?) to have a strong, non-dished rear wheel
and I also prefer to not fuss with derailleurs. This will be my only
multi-geared bike, my other rides are a singlespeed MTB and a fixie
commuter.
I have been researching various hub models on the internet and I am
getting the sense that, other than Rohloff, nothing on the market can
really handle anything other than light duty typical of comfort or
casual bikes.
To put this into perspective, I am 6'6", 250+ lbs and, although I ride
smoothly, can apply a lot of power to the pedals when I want to. Throw
on some cargo, and my habit of dashing off down the odd fire road or
stretch of singletrack, and I wonder if one of these hubs could handle
it.
At 4-5 times the cost I just can't afford a Rohloff. Are any of the
current offerings from S-A, Shimano or SRAM suitable for my needs, or
should I stick to a derailleur and keep saving for a Rohloff in the
I am 6'8" tall and weigh close to 350 pounds at this time. I have
used several gearhubs on my bikes at body weights of 330 to over 400
pounds, and I have been an active cyclist all that time. Some of
these bikes have been regular transportation, and some of them have
been utility rides for carrying things.
The gearhubs now in my stable include SRAM Spectro 7, Shimano Nexus 7,
and a Rohloff Speedhub. My wife's bikes feature Sachs Pentasport 5
and a Rohloff Speedhub. Bikes that I spent some time with before
passing on to others used Sachs 7 and Shimano 4 gearhubs. Not one of
these gearhubs has broken outright, but they have not been entirely
without problems.
Because I had been warned by a shop owner that some of his customers'
Nexus 7 hubs developed problems related to high torque loads, I used
my Nexus 7 hubs only in 20" wheels, whose reduced diameter
proportionally diminishes gearbox loads. They feel draggier to me
than my other gearhubs, but they have been reliable. I understand
that Nexus 8 hubs have improved efficiency compared to Nexus 7 hubs.
One very nice feature of Nexus hubs is that all the shifting apparatus
is tucked inside the chainstays and dropouts, out of harm's way.
The Sachs and Sram 7-speed hubs in my bikes seem more rugged and freer-
running than the Shimano hubs. They have a wider overall gear range,
too-- with some of the larger steps between gears bordering on too big
for my taste. I once tore out an anti-rotation washer on one of these
hubs, which is the biggest mechanical issue I've had to date with any
gearhub. (When the axle spins, the hub bearings go out of
adjustment.) In that case, I had only one anti-spin washer in place,
because the thick aluminum dropouts of my bike didn't leave me room to
put one on each side (my usual arrangement). Since then, whenever I
have room for a washer on only one end of the axle, I have used a
special washer I machined from steel bar stock.
The SRAM 7 hub that I still have in service is in a 29" MTB wheel.
That's a worst case scenario for hub torque. Although I don't take my
29er off-road, I don't spare it any of the usual hardships of city
riding. I use 40-21 primary gearing, for a range of 32 to 97 gear
inches. So far, it has been boringly reliable in this application.
Note that the parts kit that comes with the SRAM Spectro 7 hub
contains only one anti-spin washer. I have heard that this serves the
role of a structural fuse to protect the gearbox from potential
overloads. I will still use two washers whenever I can. Spare anti-
spin washers and spare M10.5 axle nuts are cheap and readily
available; it's a good idea to have some extras set aside. (The nuts
strip out easily because of the interrupted thread on the flatted
axle.)
The SRAM P5 Cargo hub is the only gearhub that is explicitly rated for
the kind of load you are discussing. It has a slightly narrower
overall gear range than the regular P5 hub-- close to 2.5:1. I have
not used one, though, so I can't comment on it from experience.
The Rohloff Speedhub is a marvelous piece of equipment, but it's not
without its idiosyncrasies. Mine gives occasional false neutrals in
its problematic 8th gear-7th gear shift. None of my other gearhubs
have done that.
If you can make peace with a single speed for all other uses besides
touring, then I think you will probably be happy with a 7- or 8-speed
gearhub for touring. Exercise restraint in how tall you make your top
gear; there's little reason to go much taller than what you have on
your fixie. That will leave you plenty of low gears for coping with
heavy loads and unfavorable conditions.
A friend of mine who is half my size recently broke the axle on his
Sachs 3x7 hub. He was using it in a single speed MTB frame that had
been amateurishly widened to accept the new hub, and the misaligned
dropouts appear to have been the critical factor in the failure of his
hub. Check your dropout alignment before you put your new bike in
service, to avoid unnecessary problems.
Good Luck!
Chalo
