Author Topic: Rohloff v. Derailleurs: Efficiency: The Fine Detail  (Read 13849 times)

Andre Jute

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Rohloff v. Derailleurs: Efficiency: The Fine Detail
« on: August 15, 2021, 11:50:41 AM »
JohnR wrote in another thread:
Quote
Perhaps the Rohloff hub is slightly less efficient than a derailleur system in optimum condition, but for how long does that condition continue unless the rider is a fanatic who diligently cleans the drivetrain after each ride?

I'm not so sure that even "a fanatic who diligently cleans the drivetrain after each ride" can reverse Time.

Take two bikes, a Rohloff and a derailleur, which are both new and factory spotless, and tuned by the finest mechanic. Put them on the street. Ride them.

The Rohloff may start out fractionally less efficient than the derailleur; we have laboratory evidence for that. Everyone can decide for themselves whether they want to consider the difference significant. I find it risible that serious people should waste their time on differences that on the road will disappear within a few miles.

But, when the bikes return from the ride, the Rohloff is in exactly the same condition as when it left, and the derailleur bike's efficiency starts to degrade the moment you ride it. The longer the ride, the more the more the derailleur bike's efficiency degrades.

In addition, you can fit a Hebie Chainglider to the Rohloff, which keeps the chain in its initial, most efficient condition, whereas you cannot fit a Chainglider to the derailleur bike, and dirt on the chain adds to the derailleur's relative inefficiency compared to the Rohloff, cumulatively as the miles mount up.

And, no matter how the owner cleans the derailleur bike, the damage done by the grinding paste of dust and oil accumulates and undermines its ride-on-ride efficiency, whereas the Rohloff, if properly serviced, merely runs in and becomes more efficient.

And that's on tarmac. Off the blacktop, the process of differentiation by grinding paste accelerates in favour of the Rohloff. And in mud, which the Rohloff was designed for (also for sand on the beach which ruined Bernd and Barbara Rolloff's derailleur bikes on their honeymoon), there's obviously zero comparison.

I fail to believe that there's a general case that derailleurs even in exceptional circumstances (a short ride when brand-new?) are more efficient than a Rohloff almost anywhere outside a laboratory. It's an argument about how many angels can dance on the head of a pin.

As for the foolish argument (reported by Moronic from the net) that the Rohloff seals are a drag curbing one's speed on the downhills, on the steep downhills of West Cork, members of the peloton who tried to race me arrived where I waited for them at the bottom of the hill with white lines of fear around their mouths while I laughed with the exhilaration of speed. Come again, boys!

Once you admit the inescapable logic above, you need a wholelotta faith to believe in the greater efficiency of derailleurs in any but the shortest term.

DISCLAIMERS: Rohloff hasn't paid me anything (yet). Since we're all so woke and bicyclesexual now: we respect your right to ride on derailleurs even if only to honour the history of the bike, or because you already paid for the derailleur bike, or because you like the precision of your gear changes, or because the bike belonged to your dad, or because you think it goes faster, or because you look cool on it. Any reason will do, as long as it is your reason. We also respect your right to practice scientism rather than science, but please don't do it near me as I'm allergic to the whiff of corruption.
« Last Edit: August 18, 2021, 04:44:44 PM by Andre Jute »

martinf

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #1 on: August 15, 2021, 01:36:19 PM »
Though I am a convinced hub gear fan, I'm not quite so sure as André that derailleurs always quickly become less efficient than a Rohloff.

There is some evidence that even derailleur systems improve slightly after use, the difference is that this happens after a couple of hundred kilometers in clean, dry conditions, and declines fairly steadily afterwards with wear.

A Rohloff takes several hundred or several thousand kms of use to wear in and improve, and (AFAIK) stays at peak efficiency for a very long time if the oil change procedure is respected. A chain drive on a Rohloff is subject to similar wear to a derailleur chain, but this happens more slowly because the chain is (usually) always perfectly aligned and (again usually) doesn't have to bend around tensioner pulleys.

And, as André says, to keep the external parts of the system fairly clean, it is generally possible to fit a Chainglider to a hub-geared bike, thus significantly extending the useful life of chain/chainring and sprocket, at least in temperate European conditions. 

What does seem clear to me is that a reliable hub gear system (some models aren't) requires much less maintenance than a derailleur system. This isn't much of an issue for a Sunday racer who only rides in clean, dry conditions, but is much more important for all-weather commuting, long-distance touring and other uses which involve bad weather, dusty tracks or suchlike. 

My benchmark for comparing derailleur and hub gearing is my last long tour on a derailleur bike. 3,300 kms with an old mountain bike converted with pannier racks and drop bars. The first chain lasted about 900 kms on the original factory lube without any need for cleaning or lubrication - during this time the weather was dry, and I only did a few kms on stony tracks, there would have been no advantage using a hub gear for that part of the trip. Then the weather changed, with light to moderate rain washing sand and grit onto the minor roads I was using, 300 kms further on the chain was well worn, so to preserve the sprockets and chainrings I replaced it with a new one, cleaning the multiple sprockets, chainrings and derailleur pulleys as best I could. The new chain only lasted a few hundred kms before a combination of wet weather followed by riding on dry, dusty tracks caused excessive wear. Same for the third chain, a combination of wet weather and mild off-road riding had it skipping on the smallest sprocket after a few hundred kms. And the fourth one was completely worn out by riding on sandy cycle tracks in wet weather while riding home along the Atlantic coast of France.

With a hub gear, I might have used the same number of chains, though I somehow doubt it. In any event, it is much easier to wipe one chainring and one sprocket clean while on tour rather than trying to get the muck off a triple chainring and 7-speed cassette.  From subsequent experience using a hub geared bike with a Chainglider for intensive winter survey work in wet and muddy conditions I reckon I could have probably done the same tour with a Rohloff and Chainglider and running one new chain on just the factory lube for the entire tour.

JohnR

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #2 on: August 15, 2021, 02:10:58 PM »
Transmission maintenance (and general bike cleaning) for my Mercury during my recent LEJOG (~1070 miles) was zero. I had checked the chain for stretch before I set out and it was fine. I'll check it again soon now that it has accumulated 5000 miles. I had also scraped off a bit of muck (I think it gets into the Chainglider around the rear sprocket) and added a bit of dry lube as part of the pre-ride preparation. While none of the other bikes, all with derailleurs, suffered ride-stopping problems, there was a significant amount of cleaning and maintenance. The last derailleur bike I had was ridden through a winter on my local roads during which time the transmission got extremely filthy and very hard work to clean (I bigger issue for me than cumulative worsening efficiency). That's when I resolved that hub gears were a good idea with the brief use of a s/h bike with the Alfine 11 (not enough range for some of my local hills) before deciding to ignore the price tag and get a bike with a Rohloff hub.

Andre Jute

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #3 on: August 15, 2021, 05:00:38 PM »
martins wrote:
Quote
Though I am a convinced hub gear fan, I'm not quite so sure as André that derailleurs always quickly become less efficient than a Rohloff.

There is some evidence that even derailleur systems improve slightly after use, the difference is that this happens after a couple of hundred kilometers in clean, dry conditions, and declines fairly steadily afterwards with wear.

I'll take this point as read from experience, Martin. But I can't help noticing that 200km of derailleur improvement before an expected decline is pretty marginal.

I used to be disgusted with chains, and even cranksets (Nexus ali, with the chainring attached to the crank), which lasted less than a thousand miles in far, far more favorable conditions than you last derailleur tour, but I'm just stunned by chains that give up the ghost in 300km even in the conditions you describe.

Transmission maintenance (and general bike cleaning) for my Mercury during my recent LEJOG (~1070 miles) was zero.

One of the reasons I splashed out on a Rohloff despite having several other good bikes was in preparation for being old and not wanting to bend over the bike for routine maintenance: I was, in the most literal sense, developing a near-zero maintenance bike, partly as an intellectual exercise and partly as future-proofing. The only service items left on it are chain (I run it in the factory lube for its entire life inside a Chainglide) brake block, and cable replacement when required, hub oil replacement and, at the same time, a shot of grease to the EXT box. Every second year I wipe the dust off my bike whether it needs it or not. I have a towel near the bike for wiping it down when it comes in wet, but that's not as common as you might think when you hear "Ireland", because I can choose my short rides to suit the weather. Also, the country lanes I ride are all crowned, and none of them are on the flat for long, so they wash clean and, except in the harvest season, there is amazingly little dust on the roads, certainly nothing like the bike-hostile roads Martin describes.

If seems that with your and Martin's input we've achieved an equilibrium opinion:
"that even derailleur systems improve slightly after use, the difference is that this happens after a couple of hundred kilometers in clean, dry conditions, and declines fairly steadily afterwards with wear" whereas a Rohloff improves perceptibly over about a popular guess of 6000km or miles (it makes little difference with such large numbers) and given manual-compliant servicing then remains there for an unknown distance, but we hope for at least outlier experience of 200,000+km.

I'll take that.

PH

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #4 on: August 15, 2021, 07:21:19 PM »
Horses for courses.  Just how do you measure efficiency? The tapping along gear on my derailleur and Rohloff Mercury are almost identical, good chainline on the dangler, perfect on the hub, quite similar bikes in other ways, particularly position and tyres (The two biggest variables when considering cycling efficiency) The derailleur bike is noticeably easier to pedal, so much so that I'm likely to be up a gear and 2kph faster for a similar effort.
Even on an easy flat ride I'm unlikely to spend more than 60% of the time riding like that, how far away and how much time and the calculation becomes impossible. Even if you could come up with a number to demonstrate that, it would only be your number and would likely vary day to day and ride to ride. it's then largely down to personal preference, there's a lovely Mercury in the for sale boards, a rider has decided they prefer their derailleur bikes, I feel the opposite, in fact I haven't ridden my derailleur bike this year!  That doesn't mean one of us is wrong.
For me, the big efficiency gain would be really hard to measure, with a IGH I'm always in the right gear.  I was on a club ride yesterday that included the appropriately named Long Hill out of Buxton and the classic Holme Moss (390mtrs over 7km) On the Mercury of course, I guarantee I changed gear more often than I would have on a derailleur bike and being in the right gear is always more biomechanically efficient than not. Try measuring that!

martinf

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #5 on: August 15, 2021, 10:21:30 PM »
Horses for courses.  Just how do you measure efficiency?

Not very scientific, but I just ride the bike several times over the same circuit before and after changing the gear system (or other component) and compare the average time taken.

That's how I arrived at no significant difference speed difference between a moderately used but clean and well-lubricated 3x7 derailleur system and a new (i.e. not run in) Nexus 8 Premium hub over a moderately hilly circuit of about 50 kms. I did replace the grease originally in the hub with a synthetic gear oil before building the wheel. This result was not what I expected, I thought there would be a noticeable drop in efficiency when changing to the hub gear. Perhaps the ease of gear changing on the hub gear compensated for the lower mechanical efficiency demonstrated in the (few) laboratory tests accessible on the Internet?

I used the same method to convince myself that a Chainglider wasn't an energy hog - 4 times round a 25 km circuit before fitting and 4 times after fitting over a period of about 10 days. Again, no significant difference in average speed, and again not the result I was expecting, I thought there would be at least a small efficiency penalty with a chaincase that just sits on the chain.

Comparing my two lightweight day bikes over the 50 km circuit, my old derailleur bike is consistently faster than my "new" Rohloff equipped Raven Sport Tour by a margin of about 1 km/h. But the overall gear range on the derailleur bike is set higher, which means I must push harder on the steepest uphills. So I feel less tired after doing this circuit when I use the Raven Sport Tour. Riding positions are about the same on the two bikes, but the derailleur bike is about 1 Kg lighter (probably not a factor) and has 28 mm Schwalbe One tyres, which are, according to tyre rolling resistance tests, supposed to be significantly more efficient than the 35 mm Kojaks I had at the time on the Raven Sport Tour. But the fatter tyres make the Raven Sport Tour more comfortable to ride over long distances, and I find I don't choose the derailleur bike very often nowadays, the Raven Sport Tour is simply more fun to ride. This would probably be different if I was into time trials, racing or Audax riding.

Andre Jute

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #6 on: August 15, 2021, 11:25:12 PM »
On the Mercury of course, I guarantee I changed gear more often than I would have on a derailleur bike and being in the right gear is always more biomechanically efficient than not. Try measuring that!

Been there, done that, got bored and moved on to something more exciting before the T-shirts arrived. In the 90s and the noughties, I rode a fixed, measured circuit every weekday and sometimes on weekends too. My bikes were consecutively derailleur, Shimano Nexus, Shimano Di2 "Smover" -- the full automatic not the cutdown one they now sell as DuraAce, and Rohloff. The automatic gear changing bike was fastest of all precisely because it was always in the right gear relative to the effort I put in and the road, the Rohloff came second, the Nexus HGB third and the derailleur bike last of all. Measured!

If you haven't seen its description and photos yet, the fully automatic bike (with electronic active suspension as well, oy vey!) is at
http://coolmainpress.com/BICYCLINGsmover.html
and journeys on it are at
http://coolmainpress.com/BICYCLEKilmacsimon1.html
and
http://coolmainpress.com/BICYCLEKilmacsimon2.html

I'm very surprised to hear that anything at all is unmeasurable. I've certainly never found anything that I couldn't somehow measure, including the ghostly lovers in my family's house.
« Last Edit: August 16, 2021, 03:43:58 PM by Andre Jute »

JohnR

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #7 on: August 16, 2021, 08:24:38 AM »
I find that the weather (particularly the wind) affects the time I take to get round one of my circuits such that the effects of changes in equipment are difficult to discern. While I initially felt that my Birdy Rohloff was almost as fast as the Mercury I'm now thinking the first ride on the Birdy was helped by favourable weather. The Birdy has a dynamo so I thought that was causing some extra drag so I disconnected the lights to reduce that, without obvious improvement. I now wonder if the poor chainline and chain tensioner on the Birdy is creating unwanted drag while the Rohloff hub has only accumulated a few hundred miles so far. Comparing two Rohloff bikes is almost going off-topic except it highlights the difference of making comparisons in other than laboratory conditions.

PH

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #8 on: August 16, 2021, 10:10:36 AM »
Comparing two Rohloff bikes is almost going off-topic except it highlights the difference of making comparisons in other than laboratory conditions.
Yes this.  AJ's testing has so many variables that isolating one element isn't possible, it becomes anecdote not data.
I used to have a fast road bike, I have the data to prove the rides I did on it were always the fastest. Except - I didn't like getting it dirty so it never (Intentionally) went out in the rain, the tyres were a bit narrow and delicate so it stayed off bridleways and cycle paths, I always wore cycling gear rather than my customary casuals, it had no fitted lights or rack or guards, it had a steep ST and low bars so uncomfortable for more than 100 km, and I'd only take it out if intending to do a fast ride...   
I'm also faster on my Alfine Mercury than the Rohloff, but it hasn't got low enough gears to take it anywhere seriously hilly.  My urban Rohloff is the slowest bike I own, you can probably guess why.
We have to put such things in perspective, we're talking in gearing systems differences of a few watts, that isn't insignificant but neither is it likely to be the determining factor for anyone contemplating one. 

Moronic

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #9 on: August 16, 2021, 12:04:37 PM »
Wow I'm glad Andre started a new thread for this - lots of enthusiasm and helpful info for people researching Rohloff user experience.

As someone new to Rohloff I'm close enough to my purchase decision to remember what was mainly on my mind as I pondered. The fear I had was not whether my derailleur riding friends would gain an extra 20 metres on me every kilometre just from my choice of gearing system.

What worried me was that I might find the hub frustratingly draggy or indirect. So that when I was pedalling it felt as though I was putting a fair bit of effort into just spinning Rohloff planetary gears, or overcoming seal drag.

Google commentary on the Rohloff, and track down every stray thread, as I did even while waiting for my ordered Mercury to arrive, and you'll find bits and pieces to that effect. Much of it possibly coming from early hubs, which it seems were noisier.

What has surprised me - and obviously pleased me - since I started to get out on the Rohloff is that none of those fears has had any justification from my experience. I experience the Rohloff transmission as feeling freer and more slippery than I remember of my derailleur transmission.

I rode recently with a friend who had a derailleur equipped bike, which is old but reasonably well maintained. He is about my size and we swapped steeds for a while. Not for an instant did I think: wow this thing is so easy to propel, or, wow it's great how free this derailleur drivetrain feels when I pedal.

It might be argued that a factory fresh set of derailleurs might have felt a bit better. Um, yes, and that's part of the point.

Move from feel to measured drag and we have ways to discover that, under specified conditions, one system or the other is marginally less efficient.

That's dandy, but it doesn't matter much for non-racers if the less efficient system doesn't feel less efficient.

For the rest of us I'd argue that how it feels to ride is the important bit here. The bike that feels better to ride tends to get ridden more. And the more you ride, the stronger you get, and the faster you'll go on either geartrain.

Those of you who ride both systems frequently are obviously well placed to comment on how each feels for efficiency - as opposed to how you think or know it is from measurement. Has your experience matched mine? Or do you indeed think Oh, not this old grinder whenever you step  back onto your Rohloff steeds?
« Last Edit: August 16, 2021, 12:11:06 PM by Moronic »

Andre Jute

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #10 on: August 16, 2021, 03:40:14 PM »
Comparing two Rohloff bikes is almost going off-topic except it highlights the difference of making comparisons in other than laboratory conditions.
Yes this.  AJ's testing has so many variables that isolating one element isn't possible, it becomes anecdote not data.


That may be comforting but it is nonsense, as I shall explain shortly.

Martin has the right idea:
Horses for courses.  Just how do you measure efficiency?

Not very scientific, but I just ride the bike several times over the same circuit before and after changing the gear system (or other component) and compare the average time taken.

On the contrary, perfectly scientific, the more tests you take, the more scientific.

All the four bikes I cited went over the same 7.5m circuit in the same direction more than 440 times, year-round. Thus every bike partook of all the offered weather conditions, all of my conditions that may influence speed, etc. Two of those bikes were Dutch vakansiefietse with Shimano Nexus boxes, the only difference being that one had a fully automatic gearbox and adaptive suspension aiding efficiency; if any upset in the results were likely, it would have shown in these two. The other two, derailleur and Rohloff, were steel, another layer of indicators in case there was something wrong with the count. I wrote down the order I expected before extracting the data, as a hypothesis, if you like, and the result was precisely as I expected. You're arguing against a huge, huge statistical probability for my result being rock-solidly unimpeachable.

1760-plus rides over the same piece of road on four bikes is a long way up the ladder of certainty from an anecdote, laboratory or none. That large a sample smoothes out the small daily fluctuations until hardly a ripple disturbs the result.

You're the one trying to hold up anecdotes of single rides as contrary evidence, Paul, as in your post above, not me.

***
In any event, by the evidence of the net, the average Rohloff tourer isn't a kid wet behind ears and possibly a fashion victim but a mature party of judgement and means. He can, if he wishes, scour the net for Rohloff information, and form his own judgement; if he is serious he is likely sooner or later to land either here or, if he speaks German or has discovered Google Translator, on the good German board, where the various opinions eventually combine to form a singular opinion, which is then his initial opinion. We're just privileged to be on board not too far after the beginning of Moronic's journey. We won't mislead anyone by a variety of pretty much mainstream opinions.

As for a laboratory, back when I took these rides, I financed a prototype lab to build and test the high tension (up to 2000V) thermionic tube (valve) audio amplifiers I designed for a Japanese maker. My engineering partner had spent his life at the cutting edge of instrumentation. He was no faculty common room talker: he'd done it daily all his life. When I suggested to him that we should test my new Rohloff, he pointed to the tarmac on the parking lot outside and said, "The best test is the one you already performed on your earlier bikes. Match it." So that's what I did. When I caught up, a bit late, on Kyle and Berto's Rohloff v. derailleur tests, I saw instantly what he meant: those tests were pie in the sky, useless for real life decisions. A one or a two per cent efficiency difference when the power source is outside the equipment being measured, linked by a chain, will just disappear into any number of variables, like the fact that their Rohloff wasn't run in but brand new. Ouch!

And I repeat: in real life the Rohloff's efficiency is the average over the ride, which is very likely to be a constant over many rides on the same course, whereas the derailleur's efficiency is not fixed when it leaves but should be measured and calculated upon its return, dirty and degraded. The Rohloff average efficiency will be the next best thing to a flat line, the derailleur efficiency line will always, except for a brief honeymoon early in its life, point downwards.

By the way, Bernd Rohloff's reply
https://www.hupi.org/HParchive/PDF/hp55/hp55p11-15.pdf
to Kyle & Berto gives a whole bunch of considerations, including ones from sports medicine that I picked up on immediately I read the K&B article, of the type that my own tests would subsume under straightforward statistical weight of number of tests.

But for my money the best thing that Rohloff and Greb do in their reply is "Figure 6: SPEEDHUB 500/14 efficiency comparison. Gears 8-14 shifted to the left to compare with gears 1-7." It shows why I'm so keen on Gear 11 that my whole transmission is planned around it and the overdrive gears come into use here in the Rome of West Cork (very hilly!) only on the downhills.

PH

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #11 on: August 16, 2021, 04:06:07 PM »
Comparing two Rohloff bikes is almost going off-topic except it highlights the difference of making comparisons in other than laboratory conditions.
Yes this.  AJ's testing has so many variables that isolating one element isn't possible, it becomes anecdote not data.


That may be comforting but it is nonsense, as I shall explain shortly.

I look forward to that explanation.
Happy to peer review it.

Andre Jute

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #12 on: August 17, 2021, 10:40:37 AM »
Comparing two Rohloff bikes is almost going off-topic except it highlights the difference of making comparisons in other than laboratory conditions.
Yes this.  AJ's testing has so many variables that isolating one element isn't possible, it becomes anecdote not data.


That may be comforting but it is nonsense, as I shall explain shortly.

I look forward to that explanation.
Happy to peer review it

Heh-heh! You should consider a career in stand-up comedy, Paul. The clubs are crying out for you.

So as not to confuse those who come after us, the promised explanation followed immediately upon the promise in the same post in this thread at:
http://thorncyclesforum.co.uk/index.php?topic=14325.msg106935#msg106935



PH

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #13 on: August 17, 2021, 11:20:47 AM »
Heh-heh! You should consider a career in stand-up comedy, Paul. The clubs are crying out for you.
I tried to get booked but you've cornered the market, This one
Quote
All the four bikes I cited went over the same 7.5m circuit in the same direction more than 440 times, year-round. Thus every bike partook of all the offered weather conditions, all of my conditions that may influence speed, etc. Two of those bikes were Dutch vakansiefietse with Shimano Nexus boxes, the only difference being that one had a fully automatic gearbox and adaptive suspension aiding efficiency; if any upset in the results were likely, it would have shown in these two. The other two, derailleur and Rohloff, were steel, another layer of indicators in case there was something wrong with the count. I wrote down the order I expected before extracting the data, as a hypothesis, if you like, and the result was precisely as I expected. You're arguing against a huge, huge statistical probability for my result being rock-solidly unimpeachable.
is guaranteed to have them rolling around the aisle in any first year science class. 
I know you enjoy writing fiction, but you really ought to be able to tell the difference.
This is a forum, if you wish to put forward opinions as undisputed facts, then you need to do a lot better than offer a series of anecdotes, otherwise they're no more or less nonsense than anyone else's opinion.

Andre Jute

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Re: Rohloff v. Derailleurs: Efficiency: The Fine Detail
« Reply #14 on: August 18, 2021, 12:30:09 PM »
Pfffft.

I can understand that you're embarrassed to be caught out rushing to judgement without asking me a single question about what I based my conclusion on:
http://thorncyclesforum.co.uk/index.php?topic=14325.msg106933#msg106933
If you had asked me, I would have told you about the 1760 data points underpinning my conclusions. Next time I'm going too fast for you, do ask. You'll find me charming and helpful.