Touring - Gearing help needed for my sturmey 8spd xrf8w
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02-01-11, 12:16 PM
Building up sort of a freak bike
Iro Phoenix 58cm
cane creek scr5
dia comp #610 centerpulls
some cheap velo vinyl seat which i'll switch out to some white colored leather seat with springs (any suggestions)
ritchey comp stem and seatpost
all city clips and straps
mks gr9 pedals
tubus tara front
tubus logo rear
hubub bar end shifter adaptor
velocity chukker rims (need to be built)
all city new sheriff 32 hole fornt hub
all city 612 crank 46tooth (here in lies the problem)
i can get this down to 42 tooth paired with the included 25tooth cog
maybe not ideal. There's a lot of hills around these parts though. I live in the Santa Cruz Mountains.
I'm trying to figure out what the best configuration is since i could change the sprocket to anywhere from 16-25 with either a 42 or 46 tooth chainring.
just consider this bike would be loaded and used for light touring maybe a week max.
and pardon my ignorance on this but I have never built up a bike before and am trying to learn here... Thanks
02-01-11, 12:27 PM
oh yeah I'm using 700x32
First, there are other threads on bikeforums that talk about this hub; search places like commuting, utility, and mechanics for lots of opinions.
I don't have any touring-specific comments on your proposed build (or any touring-specific comments at all; I'm just lurking here to learn), but I built a round-town sort of bike for my wife with that hub, and the results are less than ideal. I understand they've redesigned it since then so that it's supposed to be smoother shifting, but one thing that apparently has not changed is that the hub is geared really high.
On the one I built, I'm running a 36T chainring and a 25T rear cog and 700x35s, and it's really pushed the limits of what my wife can comfortably pedal. She's reasonably fit, not an avid cyclist, but it's a challenge. I ride a lot more than she does (though nothing like what folks in this forum do) and it's not real comfortable for me either. My regular ride (mainly for 7 miles to work and back) is a Nexus 7 speed internal hub and its range is much more reasonable.
YMMV, but my guess would be that you wouldn't get enough low range on that hub to haul much load around. I calculated all the ratios and gear inches on both and I can try to find that and post it, or you can go to sheldonbrown.com or a number of other places and do the math. Figure out the low-end gear inches on your current bike, determine if you are comfortable hauling a load with that, and see if you can get down there with this hub before you lay your money down. I wish I had.
PS If you still wanna go this route, I know a guy that will sell you the hub built into a really nice wheelset and the Dia Compe 610s! ;)
02-01-11, 03:28 PM
I already have the hub and had this frame so I figured might as well see what happens. If i would have known though I apparently get pro deal with nuvinci so could have got that instead and prob should get that and swap out the frame for something else but i dont want to right now. I will probably buy a soma frame and the nuvinci in the future and see how this setup works. maybe i will have to buy a new crankset :-(
You gotta match the crankset to whatever rear gearing/wheels you're using with any set up. If you just have to use a particular component regardless of its suitability, you shouldn't expect things to work out so hot.
Here's my Dawes Briercliffe XRK8(W) light touring bike w/ 25T cog, Sturmey crankset w/ 30T chainring, 26 x 1 3/8 (ISO590mm) wheels
tcs, that is a very interesting looking bike. From purely an aesthetics pt of view, it is pretty darn neat looking. The way the chain looks too with the equalish front and rear sprockets gives it a unique look in itself.
31-100 g.i. nice range. Ive never ridden an internal geared bike, but they certainly do have a nice clean look. Slap on an enclosed chainguard and it would be great for riding in rainy, dirty conditions so you wouldnt have to think of the chain.
02-01-11, 09:15 PM
I have one of these too, and after a week of comparing it to my MTB gearing, I'd say you'd need a 25T chainring for climbing steep hills, and I probably would use a 32T for flat/fast road riding.
At the very least, you'll need to ditch the track crank and get a cyclocross or MTB crank that will use a 32T or smaller chainring. No getting around that if you want to be able to use all the hub's gears.
Think of it this way: lowest gear is a 25T cog, and the highest gear is the equivalent of a 7.7 tooth cog.
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