HUB GEAR RANGE, NUMBER AND GAP? SHOULD THERE BE TWO ROHLOFFS?
Racers, and to a great extent fast commuters, want close gear spacing so as most efficiently to translate effort into acceleration or climbing power.
Putterers, recreation riders, utility riders, campers and several varieties of tourers all want decent gear range, but don't generally need such close spacing between gears.
When I rode Shimano Nexus 8-speed boxes, I found both the range and the gear intervals perfectly suitable to my sort of riding. The test of this pudding was that my Cyber Nexus fully automatic gearbox (the Dura Ace version is a crippled "assisted manual shifting" version of my fully automatic comfort version) never once felt like it was in the wrong gear for the effort I wanted to expend.
However, I moved to a house up a steep hill and wanted a gear or two below the Shimano setup, which I already felt limited me a little by running out of puff on the downhills at under 30kph at my preferred cadence which is never over 60rpm. So a change of sprocket or chainwheel wouldn't solve the problem while retaining the Shimano.
It had to be a Rohloff for its greater range, well over 500% for the Rohloff against just over 300% for the Shimano. With a 38x16 chainwheel/sprocket setup, the highest input force permitted by Rohloff, this would give me three evenly spaced gears below those I had with the Shimano Nexus box. The "top speed" with the Rohloff box is similarly limited to under 30kph.
As an aside, it is worth noting that the Thorn designer tells anyone who wants to take the guarantee risk onto themselves that the Rohloff box is strong enough to gear lower, say 36x16. If I were a loaded tourer, I would take his advice and coast down the hills. I would resent that though, because the high spot of my day is speeding down the far side of hills I ascended the hard way!
But I do day tours and the occasional short credit card tour, and my heaviest load is actually a case of wine from the supermarket less than a kilometer away. On cool days I have a gear or two to spare on the hill for which I bought the Rohloff box, and on hot days the lowest gear lets me stay on the bike at a slow walking pace, just within the limits of balance; the younger women with whom I cycle all get off and push. When I'm really old, I might need all those gears, or perhaps even 36x16.
So the Rohloff lets you set up the range as low as anyone is likely to want to go.
The problem arises at the other end. We'll return to that.
Through the gears, now that I'm used to the Rohloff box and it no longer draws attention to itself by being stiff, I find that often I change several gears at once, no pause in the intermediate gears, to find the right gear. Clearly, the conclusion must be that gear spacing, optimized for racers, is simply too close for my sort of puttering/recreational/utility use -- even though I live in a town and countryside full of hills.
That raises the question of whether all the gears need to be evenly spaced, and particularly whether they need to be so closely spaced, for either utility or racing applications.
It is clear by motoring analogy that close ratios at the bottom end are a good thing. Initial close ratios will move the racer off the line efficiently, and get me up my hill without exposing me too long to cars on the flat bits, which include the crossings. Those are two extremes where racers and putterers can agree.
But I for one would trade the close gearing through the middle range of the Rohloff box for more extension at the top end. To be absolutely clear: I think that in the centre of the range 17-20% steps would be practically as good as the present spacing even in hilly country, and I don't see why the top three gears cannot be spaced up to 22% apart given of course that this leads to an extension of the overall range. And, since the development work is likely to be expensive, let's overfill the requirement and make the range 700% so that in a few years some idler doesn't say 650% (which I might find adequate) is too little.
On many of my hills I touch 50kph and on a few 55 and 60kph even with a pedal long since gone limp at my very best cadence. I reckon with a wider range I would need to give up nothing at the bottom end, and at the top I could help gravity to extend the same hills to 70kph (1). That would be magical.
One wonders whether a similar scheme would not benefit racers as well, a sort of overdrive for downhill sections. If not, there could be two Rohloff boxes, one for the fast guys on the flat, one for the sluggers and downhill racers.
Of course, the original Rohloff concept was about mudpluggers. It was unplanned that our sort of bikes took to the Rohloff for its low maintenance and reliability.
It is difficult to improve on perfection but more of the same is always welcome...
Andre Jute
(1) I haven't done the math. There is no math in daydreams. Why should Herr Rohloff mess with a successful product because a few speed freaks want to go 20kph faster? Not gonna happen this side of Christmas...
