are rohloffs slower than derraileurs?

[wheezy]

So are there skinny tyre, drop-bar, "fast" bikes out there fitted with Rohloffs?

[travelling]

it seems most of this thread is hogwash, unless the bike rides without a rider then i suggest the rider input is more likely to make the bike faster or slower.

Almost as stupid as someone saying that marathons are too heavy then forgetting the bike has a lump of lard riding it with fully packed ortliebs

[peter jenkins]

I think I have to disagree, Travelling.

If we are comparing different bikes ridden over the same route by the same rider, as has been done by earlier contributors to this thread, their findings have to be meaningful.

Not so sure about the weight issue, but I think heavy tyres have a disproportionate effect on speed due to their rotating mass.

I do take your point though, about overall weight rendering the weight of the tyres insignificant.

Cheers,

pj

[Relayer]

So are there skinny tyre, drop-bar, "fast" bikes out there fitted with Rohloffs?

I doubt it because of the gear changer issue on drops, rohloffs can't compete with STI for racers.

[brummie]

Dropbar, rohloff AND skinny tyres:
 http://www.bikeradar.com/news/article/santos-concept-bike-geared-for-roadies-23833

Still not as nice or useful as a Thorn !

[travelling]

I think I have to disagree, Travelling.

Of course your entitled too Peter

Sometimes however some forget we ride a bike and not a formula 1 car with a paddle gear system for that 100th of a second faster gearchange

[stutho]

>So are there skinny tyre, drop-bar, "fast" bikes out there fitted with Rohloffs?

I don't know about skinny by my Drop handled RST is equipped with 26 X1.25 Panaracer Pasela tyres which at a weight of 240g per a tyre compares favourably to the lightest of the Schwalbe Marathon (660g)

I have never timed the difference between my bike and my wife's  Flat bared RT but I wouldn't be at al surprised if I was 10% slower on the RT (due to the bigger tyres and the flat bar)

[gearoidmuar]

I don't agree with the post that talks about a gear that optimises racing speed, and that the Rohloff gaps are too big.. There isn't a gear that "optimises" racing speed, though there may be such a range. The gearing gaps in a Rohloff are pretty similar to those if you're using an 11-32 cluster. I find no significant gaps in the Rohloff setup and moreover, it's so easy to change that you change all the time. Not only that, but I found touring with a Raven Tour that I was climbing better than a mate of mine who uses a derailleur-equipped bike than I was with a touring bike of similar weight. This was not a normal finding as we're both almost identical in climbing ability. I attribute it to the fact that I keep changing with the Rohloff so I'm always in the right range. If you're dealing with the vagaries of a derailleur "system" you're less likely to provoke the thing!

[Fred A-M]

Gearoidmuar

I'd have to disagree with your seeming misinterpretation of my post.

Finding a gear that "optimises" your racing speed (ie. enables you to accelerate more quickly until you need your next "optimum" gear so that you get to your fastest possible speed in the shortest possible time) is more likely in most circumstances on a bike with narrower gaps (e.g 10%).   An optimum gear for racing is relative to the changing circumstances (not fixed) of the rider, and a narrower gap between gears (again in most ordinary circumstances) is going to increase the likelihood of finding that optimum gear for speed, particularly when accelerating up an incline.

I certainly didn't in any shape or form suggest that the Rohloff gaps are too big, and have on several occasions written about the Rohloffs merits, especially for hilly or mountainous touring, and I'm also on record as stating that this is because I also change the gears more than with a conventional derailleur (because of the reliability and general precision of the change) - so at least we agree on one thing. 

However, changing gear more frequently just makes more likely that you’re more likely to find/be in your "optimum" climbing gear, assuming that the incline or your body requires the changes.   I get the impression that your preference for the using the word “range” is more about being contrary than expressing any clarity of thought.   Range suggests there is a choice of gears.  Maybe you are referring to the front chainset?  If so this doesn’t apply to Rohloff, but you can also be in the right range on derrailleurs but the wrong gear.  It is simply about being in the right (i.e optimum) gear at the right time according to your needs whether you are racing or climbing. 

Travelling – your comments only serve to highlight your own stupidity over the valid contributions of others…..even overweight people (“lumps of lard”) have the right to enjoy lightweight tyres/bikes, unless of course you are saying that overweight people shouldn’t have a right to decent bikes of their choice and/or to maximise their enjoyment of cycling with all the resulting health benefits.  

[gearoidmuar]

Fred A-M.

What I mean by "range" in my post is "there or thereabouts"
e.g. a gear of 81-84 inches instead of e.g. a gear of 82.5 inches.

[MilitantGraham]

I don't find the gaps between gears too big. Riding typical XC mountain bike terrain, any one gear is rarely ideal for more than a few metres anyway as the track constantly changes.
I very rarely know what gear I'm in. I did 18 laps at the Bristol bike Fest 12 hour marathon last weekend and after a few laps I got to know, for example, that at the end of the fast bit across the field I needed to shift down 4 clicks for the twisty bit in the trees coming up. I don't know if I was shifting from 11th to 7th or 9th to 5th.

The extra drag of a Rohloff is a constant complaint from derailleur fans.
Surely it wouldn't be too hard for a magazine or some other independent party to commission some research in to this.
An electric motor driving the cranks with n accurate measurement of power in against power at the tyre should make it possible to compare the drag of any drive system.

[stutho]

Surely it wouldn't be too hard for a magazine or some other independent party to commission some research in to this.

See this link http://www.bhpc.org.uk/HParchive/PDF/hp52-2001.pdf

Note they were using a new hub  - a hub that has go a few thousand mile on the clock should be better

[bike_the_planet]

I don't think Rohloffs are significantly slower. Published efficiency figures show a 1-2% decrease in efficiency for the Rohloff at most. That's equivalent to a few watts of energy and equates to less than 0.5 km/h on the road. What does make the difference, though, is the bike as a whole, especially the bike's weight, type of tyres and how upright the riding position is.

As a real world example, on my racing bikes (8kg, 23mm tyres, drops) I'm reasonably fast (!) and average 28-30 km/h each ride. On my Raven Nomad (15kg, 50mm tyres, flat bars) I average about 22-23 km/h on the same roads.

(You may also have to accept that your recent cycling companion was just faster than you!!!).

Shaun

Without wishing to get into the old efficiency argument, realistically, a hub gear system that uses up to three planetary gearsets and has oil seals will be more than 2% less efficient in certain gears. Even in 11th (often misquoted as direct drive) a single planetary set is still in use. See http://www.ihpva.eu/HParchive/PDF/hp55/hp55p11-15.pdf for a resonably comprehensive test and note some of the graphs.

A derailleur chainset uses one chainring and sprocket at any one time. A rohloff chainset has a chainwheel, sprocket and one or more planetary sets in. And gears, even epicyclic, result in more loss than chains and sprockets.

As for oil seals, a free-wheeling Rohloff wheel slows down significantly quicker than a derailleur one. Chain tensioners/derailleur jockey arms result in little loss because they are not under significant tension.

However, Rohloffs have many other advantages as we all know. That's why we love 'em.


Cheers,

Tony

[mylesau]

Even in 11th (often misquoted as direct drive) a single planetary set is still in use.

Not according to Rohloff - they indicate that in gear 11 no planetary gears are in operation:

http://www.rohloff.de/en/technical/speedhub/efficiency_measurement/index.html

See Table 5.

[bike_the_planet]

Not according to Rohloff - they indicate that in gear 11 no planetary gears are in operation:

http://www.rohloff.de/en/technical/speedhub/efficiency_measurement/index.html

See Table 5.

Ummm...apologies - yes, you are correct. I had read that before, but somehow had it in my mind that it still used one planetraty set.

In which case the only losses associated with that gear would be the fixed losses associated with oil seal friction.

In which case, does anyone know how they do this? In all other hub gears, there is always at least one planetray set involved as this is the only way to transfer power from the sprocket to the hub itself. Presumably a sprag clutch?

Anyone any ideas?

Cheers