Author Topic: Rohloff - What's YOUR Opinion ?  (Read 188025 times)

JimK

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Re: Rohloff - What's YOUR Opinion ?
« Reply #120 on: August 31, 2014, 01:17:39 am »
40 mph is about my max speed, but I wear baggy clothes and sit up higher to catch more wind on a big descent.

We have bears, deer, fuel oil delivery trucks, soccer moms, and plenty of other strange things liable to dart out onto the roadway. I don't even like going 40. Yeah, someplace where the view is wide open, what a blast, I would sure let out the stops. Not around here!

il padrone

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Re: Rohloff - What's YOUR Opinion ?
« Reply #121 on: August 31, 2014, 02:29:01 am »
Yes, I was talking about descending speeds on open, clear, country road tours.

triaesthete

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Re: Rohloff - What's YOUR Opinion ?
« Reply #122 on: August 31, 2014, 02:56:36 am »
 Thanks for the proof Jim ( I sort of had you in mind  ;) )   I thought it would be a big number. Maybe there is some sort of regenerative braking energy transfer to the rider via the Brooks leather conductor that powers Dan's intellect  :o  he must get it from somewhere!
Say this in the Grayson voice:  "Air brake trousers will soon catch on and be all the rage Sir".


Andre have you noticed how the pros crash a lot these days. There are theories that many are zonked out on unbanned (ie race legal) pain killers, but there must be more to it than that. I wonder if race bike design will come back around to the old maxim "to finish first first you must finish!"

Neil, Sammy, glad you liked Harry. I'll tell Dan it was a jolly good condiment to rather than a divergence from the thread.

Neil do you think there are more like us out there?

Cheerio
Ian

Danneaux

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Re: Rohloff - What's YOUR Opinion ?
« Reply #123 on: August 31, 2014, 08:02:09 am »
Just got the bike out of the hotel storage and was playing with it in the beautiful Tree Grove park next door here in Calara?i.

I think it may be measuring error, at least in part. I bought and fitted a Sigma 8.12 computer in Germany,  and the magnetic pickup isn't solidly mounted to the spoke. Instead, it snaps over and is loosely fixed by a stainless oversleeve that allows it to still rotate on the spoke.

Even with the magnet mounted near the hub, it is a bit of a reach and at high wheel speeds, I think the sensor is missing counts, causing a spurious readout at higher speeds. It surely doesn't help to have the computer sensor mounted by a rubber o-ring. There is an option to use zip ties but mine came without and I haven't been able to source narrow ones along the way while on-tour.

<nods> Yes, far from all things being equal for a comparison, but the sensor pickup does seem to be off at higher speeds and the gap is not consistent and the mounts are shaky, so that increases the likelihood it is at least partly responsible for my impression. Certainly, the rear wheel spins freely enough when held up to see. Remember, I'm riding solo so I don't have another bike and rider to compare to on downhills and must depend on the readout.  If that's off, well, GIGO (Garbage In, Garbage Out) on data collection.

All the best,

Dan.
« Last Edit: August 31, 2014, 08:18:23 am by Danneaux »

Neil Jones

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Re: Rohloff - What's YOUR Opinion ?
« Reply #124 on: August 31, 2014, 08:46:26 am »
Hi Ian,
When I first joined the forum a few years ago there seemed to be quite a few RST owners posting on here, unfortunately since it was discontinued there seem to be far fewer. I don't know how well the Mercury is selling but there doesn't appear to be many owners posting about them. I totally agree with you that the RST is a superb and underrated bike, perhaps it is it's ability to be a "jack of all trades" that is it's downfall.

I have recently bought a used Raven Tour in great condition but just need to change a few components for my riding preferences, I will do this over the next couple of months once funds allow. I've bought it for touring and as a backup for the RST so I don't have to rush with my maintenance. I'm looking forward to comparing the two (the Tour has drops).

One thing is for certain, I love the Rohloff Hub and will never sell my RST, it's the best bike I've ever owned.

Regards, Neil.

Rockymountain

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Re: Rohloff - What's YOUR Opinion ?
« Reply #125 on: August 31, 2014, 02:12:40 pm »
I've been thinking about replying to this thread for a while. I have a Nomad Mk2 and a new Raven as well as a Bob Jackson World Tour and a Surly LHT - the latter two having traditional derailleur gears. I have always found the Nomad and Raven to be slow and hard work when pedalling for my normal 35-40 mile rides through the country lanes north of London. I have a 37 mile ride and find that I am nearly 20 mins slower (on average) on my Raven compared with the Bob Jackson. Having said that, when I use the Thorn bikes for what I purchased them for, namely fully loaded touring, I don't find much reduction in speed from unloaded. However the derailleur bikes are considerably slower when fully loaded.

I love the Rohloff when I'm on tour - both bikes are streets ahead of the Surly, for example. But my pedalling style just doesn't suit the Rohloff on normal day rides. I know a number of people here talk about doing 200km audaxes on their Ravens - I just don't seem to have the energy in my legs to do more than 100km in one day on my Raven.

For me it's a case of horses for courses. I'll stick to the Bob Jackson for my daily rides and the Thorns for my loaded tours.

BW

Fraser

Slammin Sammy

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Re: Rohloff - What's YOUR Opinion ?
« Reply #126 on: August 31, 2014, 02:56:29 pm »
Re: Downhill speeds - I too am reluctant to exceed 50kph on any pushbike. The Nomad is wonderfully stable, and the brakes work fine, but I'm just mindful of my emergency braking distance going downhill at high speeds, and the instinct for self-preservation cuts in like a limiter.

It might also have something to do with age. I was young, 10 feet tall and bullet proof once, and have ridden motorcycles well in excess of 230mph on many occasions, thankfully without incident. But I've had some close calls over the years, and have ended my motorbike career after some spells of vertigo on the bike scared the day lights out of me. These days, I try to ride in total control at all times, but I still get around.  8)

I'd also have to agree the Nomad is a slow bike in comparison with my Trek 520, and my wife feels the same way about her Raven step-through. I have put it down to weight, tyre width, riding position, etc., but maybe it is the hub. Jim, where did you get the 8% drop in efficiency from? (Physics was never one of my strong subjects.) The bikes are still a joy to ride, especially when loaded up, as Fraser points out, but I'm looking for an extended stem for the Trek to make it more comfortable for my aging bod, and will use it as my fast tourer and workout bike.

Dan, I'm not sure you will have access to one, but a GPS is by far the most accurate measuring instrument over any speed and with reasonable distance. I find my Cateye sometimes drifts at high speeds, as well.

Finally, I would think Fraser that it's unusual for someone to own both a Nomad Mk2 and a new Raven. Care to comment on their respective ride qualities?

Rockymountain

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Re: Rohloff - What's YOUR Opinion ?
« Reply #127 on: August 31, 2014, 03:26:38 pm »
Nomad Mk2 vs Raven - I actually find them very similar riding although the Raven is lighter in weight. I'm using Schwalbe Marathon Extremes 2.0 (with Grizzly CCS rimmed wheels) on both and the feel is similar. I bought the Raven as a light do-everything bike for touring and day rides but I've found it a bit sluggish for the latter. The Nomad is slightly slower, as would be expected but I find the ride a tad more comfortable (that may be down to the bike's fit - it's a 580L whereas the Raven is a 565L). The major difference comes when fully loaded with the Nomad being much much more stable.

If I had to choose on bike, I'd go for the Nomad Mk2. The Raven hasn't quite delivered on my expectations - and that's probably because it is a jack of all trades and a master of none.

Having said all that, the Nomad is a cracking bike and, in reality, I have no lasting regrets about owning two Thorns.

Fraser

JimK

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Re: Rohloff - What's YOUR Opinion ?
« Reply #128 on: August 31, 2014, 05:02:24 pm »
Jim, where did you get the 8% drop in efficiency from?

Up thread a page or two, Danneaux reported a max downhill speed of 90 kph on a deralleur bike vs 53 kph on a Rohloff bike. That was my raw input, then I used the on-line bike-calculator to try to turn that into some numbers.

Note, I wouldn't call it an 8% drop in efficiency. Using bikecalculator, it looked like a Rohloff would coast down a 13% slope about as fast as a derailleur bike would coast down a 5% slope. Tricky to get the right sense of these sorts of comparisons! Efficiency is generally about power in vs power out. Coasting at a steady speed down a big hill, there is no pedal power in, and all the work done by gravity is being dissipated by air resistance. So maybe the efficiency is undefined or maybe it is zero, but anyway it isn't really changing from one bike to the other!

I gotta say, I suspect Dan's hypothesis on a faulty speedometer, that sounds like a likely culprit. If I let myself coast down a 13% slope... well, I wear baggy clothes and sit upright, too! But I am pretty sure I would blow by 53 kph no problem. I can't imagine 90 kph, but anyway. Egads and with loaded panniers too?! But that changes the aerodynamics as well. That is one huge problem with my calculation. Bikecalculator does not have a setting for loaded panniers! I should have notched the weight up another 40 pounds or so, yeah, but still there is no knob for the air resistance of the panniers, which is no small thing.

That is one fun thing about bikes! The simple things you see are all complicated!

Andre Jute

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Re: Rohloff - What's YOUR Opinion ?
« Reply #129 on: August 31, 2014, 06:01:55 pm »
There is definitely an error here somewhere. Mechanical drag is not a linear quantity with speed. It either causes a meltdown and locks up rotating parts, or it is overcome at some low speed and either plays no further part or falls below the threshold of perception and measurablitly. It is inconceivable that the drag of a paper seal, or any other seal, would not be overcome at some relatively low speed, say 15kph/10mph. And that, basically, is what Rohloff "drag" consists of, as anyone can see who wheels the bike and notes the pedals turning by "magic power".

triaesthete

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Re: Rohloff - What's YOUR Opinion ?
« Reply #130 on: August 31, 2014, 06:31:40 pm »


Fraser, do your faster bikes have Marathon extremes fitted. I think these will make more difference than the hub ever will. I had a set on my Sterling and as you say it felt like it would be the labours of Hercules to ride it 100miles.I put a set of 2" Supremes on instead and hey presto 12 hour riding days in winter no problem.

This is odd because the Extremes are not that heavy and coast really well but under drive they are also the most draggy/sucky/dead tyres I've ever had. Go figure. Note also that they've stopped making them and even SJS were heavily discounting them  :o  Put some Supremes on your RT and be amazed. If you want fast/light but to retain some comfort go for 1.6" instead of 2".

There was another post here recently where the OP was bemoaning his faster deralieur mates and IIRC he had Marathon Pus fitted   ::)I bet his mates didn't!

Marathon Plus and Marathon Extreme; two godforsaken diving boots of tyres! Why anyone uses them when Supremes are frequently discounted I'll never know  ::) Supremes even go off road with a little care...

There seems to be a broader internet fallacy of thinking any Marathon tyre is equivalent to any other and it makes no difference. Schwalbe's marketing is a bit of a disaster in this respect. The engineers have made a fantastic range of horses for courses but this isn't effectively communicated to the end user.

I think many Rohloff bikes are mis shod and this stops anyone comparing apples with apples so to speak.

OOH I feel better now. Happy evenings
Ian


Rockymountain

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Re: Rohloff - What's YOUR Opinion ?
« Reply #131 on: August 31, 2014, 06:35:29 pm »
Yes, the Bob Jackson and the Surly both have Marathon Extremes - but it's a good point.

triaesthete

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Re: Rohloff - What's YOUR Opinion ?
« Reply #132 on: August 31, 2014, 07:59:04 pm »

You NEED to buy some Supreme's.  Night and day.

How slow are Extremes? (and don't confuse these with the olde Marathon EX). Well lets say I bought some Schwalbe el cheapo tungsten studded 1.75 winter tyres for the Sterling and they made it MUCH faster and easier to ride  ???

On the bright side though you will have had great resistance training by now and the improvement will be even more noticeable.

The Extremes are no more robust than the Supreme, carcass and sidewall is almost identical, but they have absurd amounts of tread and grip that maybe downhill racers or a trials motorcycle could use in extreme technical scenarios and nowhere else.

Not many things I dislike with a vengeance  :)   

I'm calm now.  Ah!  :P


jags

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Re: Rohloff - What's YOUR Opinion ?
« Reply #133 on: August 31, 2014, 08:45:29 pm »
the supreams are excellent for sure but i bet the grand bios is even better. ;)

David Simpson

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Re: Rohloff - What's YOUR Opinion ?
« Reply #134 on: August 31, 2014, 11:07:28 pm »
Regarding the possible problem of the bike computer not registering a correct speed when going fast, I wonder if the sensor on the fork might not pick up the magnet passing the sensor if the magnet is passing too quickly.  For this reason, I have tried to mount my sensor and magnet as close to the hub as possible.  My reasoning is that the closer the magnet is to the centre of the wheel, the slower it will be passing the sensor.

Also (more on the topic of the Rohloff hub), I haven't noticed any drag from the Rohloff while coasting at speed.  But then, I don't have any other similar bike to do a comparison.  My other bike is a 2002 Cannondale hard-tail mountain bike with an aluminum frame and 2x1.75 commuting tires.  It is much lighter than my Nomad.  There is a big hill about a km from my house, and on my Cannondale, I once hit 69 km/h.  At that speed, I was actually scared, because the bike felt like it was floating.  I gently applied the brakes to slow down, and hoped that I didn't need to do an emergency stop.  I wouldn't want to go faster than that speed on that bike.  After I got my Nomad, I rode down that same hill (on 2x2.00 Duremes), trying to go fast.  It was night, so I couldn't read my speed until I got home.  On the way down, the bike felt completed balanced and stable, not "floating" at all.  I could easily have gone faster, if I had a steeper hill.  (I couldn't pedal to go faster, since my 38/16 gearing means my pedalling tops out at 55 km/h.)  When I got home, I checked my "maximum speed for trip": 69 km/h.  What a difference between the feel of the bikes.

- Dave
« Last Edit: August 31, 2014, 11:18:00 pm by davidjsimpson »