Author Topic: A REAL COMPETITOR TO ROHLOFF?  (Read 9163 times)

mickeg

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #15 on: July 07, 2014, 02:47:15 PM »
Regarding range, my derailleur touring bikes have a range of 630 percent.  (High is 52/11, low is 24/32.)  My lowest gears are of course only used on the steepest uphills, my highest two gears are only used for long shallow down hills or when I have a strong tailwind on the flats.  Thus, the upper and lower extremes are rarely used, but are really nice to have.

For around town my Rohloff bike is fitted with a 44 chainring and 16 tooth sprocket.  But for a trip where I knew there would be steep hills I used a chainring with 36 teeth.  On that trip, I actually had both the 36 and 44 chainrings fitted to the double crankset.  After the killer uphills hills were all completed, I added a few links and adjusted the eccentric to switch from the 36 to 44 to give me the gearing I wanted for the rest of the trip, which included gearing for some long shallow downhills.

I too would like a larger range than the 526 percent offered by the Rohoff.  I however would not want the gear steps to be increased above the current 13.4 to 13.9 percent between each gear as the means to do that.  Instead I think the ideal solution would be adding two gears for a total of 16.  With this, I would not need a second chainring to give me the wide range I desire.

If you are wondering why I chose a 36 chainring for my lowest gearing, I rode up a really steep hill and noted the speed that I felt was the minimum speed where I could easily maintain balance and remain upright.  I then back calculated what chainring I would need to give me that speed with a cadence of 72. 

Quite frankly, I would not be able to pedal up a hill at my lowest maintainable speed if the grade was 20 percent.  Thus, I do not need any gears that low.

Going Troppo

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #16 on: July 07, 2014, 02:49:10 PM »
38x16 gives you an awfully low bottom gear - about 15". Any lower and you risk falling over! And if you expect to ride long 20-25% climbs then you will need a bit more than a low gear, maybe a motor as well. These sorts of grades are extremely tiring, even with very low gears. Generally it's best to aim to avoid such extremes - apart from short pinches

By my calculations, 38x16 gives you 26" * 38 / 16 * 0.279 = 17.2" lowest gear & 90.6" highest gear. I have a thing for high mountains and I found that I could've used a lower gear in Indonesia.

For my next short trip (Borneo), I'm experimenting with 40x19, which gives a lowest gear of 15.3" and a highest of 80.3". The top end is going to be too low on the flats!

This has not been a problem that I have faced at all. After 20,000kms it still operates as well as it did on the first kilometre. And I have been very slack with any service of this - have not done the suggested regrease every 500kms  :-X

Again - no problems here. The twist-shifter spins quite freely with no sign of gumming up.

Different riding conditions I expect. Lots of mud, dust & humidity in SE Asia. A major problem with the twist shifter is that it's not serviceable without changing the cables.

I'll never tour on a derailleur again and Rohloff undoubtedly provides the best IGH solution at the moment. But this thread is about improvements, non?

Going Troppo

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #17 on: July 07, 2014, 03:17:24 PM »
I too would like a larger range than the 526 percent offered by the Rohoff.  I however would not want the gear steps to be increased above the current 13.4 to 13.9 percent between each gear as the means to do that.  Instead I think the ideal solution would be adding two gears for a total of 16.  With this, I would not need a second chainring to give me the wide range I desire.

I'd love to see a solution that provided something like a 12" to 100" range, with similar 13% step ratios.

Donerol

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #18 on: July 07, 2014, 05:31:00 PM »
If you don't mind paying for it, a Schlumpf drive with a 30-tooth chainring and a 17 tooth sprocket would do it.  :)

Going Troppo

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #19 on: July 07, 2014, 11:22:23 PM »
If you don't mind paying for it, a Schlumpf drive with a 30-tooth chainring and a 17 tooth sprocket would do it.  :)

30 / 17 = 1.76, which is less than the Rohloff limit of 2.1. With a 26" wheel, the lowest "legal" gearing you can achieve with a Rohloff is 26" * 2.1 * 0.279 = 15.2". A 40x19 setup is the closest you can get to the limit and gives a gear range of 15.3" to 80.3". The Schlumpf Speed Drive would extend the top end to a whopping 80.3 * 1.65 = 132.5.

BTW, I notice that Schlumpf is not making these any more. See here for new manufacturer.

Pavel

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #20 on: July 25, 2014, 11:21:19 PM »
I feel the range offered by the Rohlof is perfect.  I don't want more.  More never ends.  What I would like however, is "more" in my  too easily tired, underpowered, legs.  I don't think that is going to happen, but that is the slant of my wish list.  :)

energyman

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #21 on: July 27, 2014, 06:08:39 PM »
Cable ties are definitely the second-greatest invention of the 20th century, after the paper kitchen roll.

......and duct tape........

Andre Jute

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Re: A REAL COMPETITOR TO ROHLOFF?
« Reply #22 on: July 27, 2014, 07:35:30 PM »
......and duct tape........

Heh-heh!