Thorn Cycles Forum
Community => Rohloff Internal Hub Gears => Topic started by: ChrisW on April 23, 2012, 09:34:31 pm
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I just finished changing the transmission on our touring tandem over from a 3x10 derailleur system to a Rohloff. Everything went OK with the install, and on the few short test rides that I did riding the bike solo, the hub shifted OK (about 10 km total). My wife and I took the bike for the first real test ride today, 40 miles / 60 km of hilly fun.
The shifting on the Rohloff hub was a big disappointment. Shifting under load was a real problem, and sometimes didn't happen at all - we often had to completely let off the power to get it to shift, which is not an easy thing to co-ordinate with two people. A couple of times, the hub got completely stuck in one gear (somewhere in the range of gears 5 to 7, but I'm not sure exactly where) - even stopping pedaling completely and jiggling the shifter did not help, we had to get off the bike and spin the pedals, jiggle the shifter, and finally all was OK again. Occasionally, the shifting was smooth and pleasant, but that was only when power input was low to moderate, and it wasn't long before we experienced another problematic shift and my confidence in shifting got lower as the ride went on and I started trying to shift less and less, which is not what I had hoped for.
The shift between gears 8 and 7 was the worst, which I had expected based on my research on this hub, but I was especially disappointed when I realized the speed that this transition happens at, which is at about 11 mph / 18 kph, and so is a shift that happens quite often whenever a mild incline is encountered, or when pulling away from a stop. When trying to make this shift, it often jumped into a much higher gear until I persuaded it to go where I wanted. We found sections of the route where we could test whether the upper and lower end of the gear range were appropriate, and we were very happy with the range, so I'd prefer to not change the gear ratio. I therefore really hope that this is going to improve.
When riding a tandem in hilly terrain, maintaining momentum is extremely important; we found the shifting on the Rohloff to be a momentum killer as we kept not being able to shift, or needing to ease off the power so much to make a shift that we lost a lot of speed, or towards the end of the ride I was trying to avoid shifting altogether, so we then ended up with a poor cadence, which also caused our efficiency to drop off.
Shifting with the derailleur setup was never ideal, which is why I decided to give the Rohloff a try, but it was never anywhere close to being this bad. I've read that shifting should improve as the hub gets worn in a little. How long is this likely to take? I'm worried that we may have grown tired of the problems and given up on the Rohloff before things start to improve.
Please also tell us if there is something that I can do in terms of setting the shifting up better. I've got the shifter positioned correctly, with the gear indicator showing the correct gear, and it shifts fine when on the repair stand, and reasonably well when riding the bike solo. The tension on the two cables is enough to keep the cables taught, but not much more and there is very little play in the shifter, so everything seems OK here. I filled the hub with oil before the first ride, so that also shouldn't be the problem. The problems are nearly all to do with shifting under load. I am the head bike mechanic at my local bike shop, so telling me to take it there to have it looked at won't help.
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In my experience, shifting the Rohloff under load doesn't really work. It shifts quite quickly so I only have to let off for a quarter revolution or so - I keep the cranks turning but just back off a touch so the torque disappears. I had never considered what a challenge that could be with a tandem! I hope some other tandem rider(s) can offer some constructive suggestions!
Usually if I am sloppy and shift with non-zero torque, the hub puts me in gear 14. When I let off the torque it'll snap back to whatever the shifter is set at. I have never had my hub get stuck at all. I wonder if your problem there is with the cables. Are you using the external shift box or the internal mechanism? With the external box you can pull the box off and turn the control shaft with an 8mm wrench. Obviously this is absurdly inconvenient but it might help with diagnosis. I don't have the internal style shift mechanism so I don't know if there is an equivalent way to by-pass the cable control.
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I agree with JimK – you cannot reliably change gears with a Rohloff hub with pressure on the chain. However you only need to take the pressure off for an instant as the actual gear change is very quick and does not require any travel of the wheel. I normally change gear as the pedals move through vertical. But I have never used one on a Tandem so can’t comment on the difficulties of coordinating shifting there. I would expect it would take quite some practice.
Another thought that may help – you can have a lot of slack in the gear shifter without causing problems. However if the shifter cables are too tight then it puts pressure on the hub and that can cause problems. Being able to rotate the shifter forwards and backwards by even 2 gear positions is not a problem for the shifting. It would mean it is tricky to see what gear you are in. I never care what gear number I am in and the markings have worn off my shifter now. Maybe back of the tension in the cables a bit to see if that helps?
I have never experienced the gears becoming stuck but occasionally I do find I will be in an odd gear. I believe Rohloff have designed the hub so that in between gears you are not going to free wheel instead you are actually in a higher gear. For me in practice this is quite rare – I assume when it happens I have over or under rotated a shift to get in that state or maybe some muck inside the hub got in the way. Either way for me it normally slips into the correct gear fairly soon, usually when the pedals go through vertical and the tension on the chain drops off.
Peter
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It sounds like the problem is never going to entirely go away. We don't actually have a dead-spot in our crank revolution because our cranks are setup 90 degrees "out of phase", meaning that the captain's cranks are a quarter turn ahead of the stoker's. This gives far more consistent power input, and reduces the intensity of the power spikes, thereby giving the drivetrain less stress and wear. We far prefer the feeling of riding out of phase (much smoother, and easier for both people to contibute as much power as they want to), so we'll not be changing that, but it means that someone is always in the power phase and there is no dead spot in which to switch gears on the Rohloff. With the derailleur setup, this did not cause too much of a problem.
BTW, we're using the external shift box with cable routing under the chainstay (OEM2 mount with Speedbone, plus 203mm disc brake).
If the shifting doesn't look like it's going to improve significantly then we'll consider reverting back to the derailleur setup, and the Rohloff could go onto a 29er hardtail that I've been wanting to build. However, that would be a shame because I had high hopes for the Rohloff.
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Like everyone else in this thread, I have my Rohloff on a bicycle built for one. But it sounds to me like you did a proper derailleur setup, and made the cables and possibly the chain too tight by Rohloff standards, which are pretty slack, 10mm of play in the chain or more, on singles, and more than 2mm play in the cables in each direction, say around 5mm total, to start, account for the gear position as well.
Andre Jute
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I would agree with Andre's suggestion. I have no problems at all with shifting the Rohloff on the tourer, even fully loaded on 15%+ climbs. I ride a tandem with derailleur gears using 90 degree out of phase cranks as well. I find the Rohloff on the single is easier and quicker to shift than a derailleur bike in all gears except from 8 to 7. I barely need to ease off the pedals at all. Maybe if you are gear-grinders there could be problems with your shifts. You may also have too high a gear range if you are always using 7 to start off. I have a gear range that has 11 as the most common flat road gear and I almost always start off from 8. I don't shift from 8 down to 7 until about 14-15kmh.
The gear cables on mine are a fairly loose setting by derailleur gear standards, however this does not cause any problems with shifting. I could well understand that setting your cables too tight may make your shifting a bit pernickity. Try loosening off the cable barrel-adjusters to give 3-4mm of play at the handlebar shifter.
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It looks like you either put the cranks in sync or go back to derailleur.
The Rohloff won't shift if there is even the slightest force applied to the crank. You might be better off with the Alfine, if they're rated for Tandem use?
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Thorn's Raven Twin brochure shows every tandem set up with cranks in-phase. There is not an out of phase crank to be seen. I'm guessing this is in fact your solution.
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The Rohloff won't shift if there is even the slightest force applied to the crank.
That is simply not true, yes you have to back off between 8 & 7 but not with any other change. Never ridden a tandem but can imagine it takes a bit of practice to get that 7-8 / 8-7 shift coordinated.
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Loosening the shifting cables to give some slack should improve the gear changing.
An oil change, double flush maybe, should remove any particles which are causing you to get stuck in a gear.
The oil flushing was necessary with my original Rohloff (sadly that bike was stolen).
I am assuming that you have a new Rohloff - in that case and if nothing above improves the gear changing then it is possible that you have one of the rare new hubs which needs to go back to Rohloff for attention.
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That is simply not true, yes you have to back off between 8 & 7 but not with any other change. Never ridden a tandem but can imagine it takes a bit of practice to get that 7-8 / 8-7 shift coordinated.
I admit I'm exaggerating, as it's possible to force it through (with a nasty clunk), but I'm not talking about backing off. Changing gears on a Rohloff is about timing and technique. Well, on the couple I've ridden anyway. I found it to be the most obvious difference between the Rohloff and the Alfine in use.
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I'm thinking that it ought to be possible to time the changes to when the stoker is in "off-power" phase without too much loss of momentum from the momentary lack of drive from either source. The Rohloff is such an awesome piece of equipment that it will surely replay the effort expelled in developing a satisfactory technique.
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We went from a conventional dérailleur tandem to a thorn raven twin rohloff tandem and were as disappointed as you. I even sent the hub back to rohloff but every problem you have outlined still occurred.
The problem stems mainly from the difficulty in completely backing off the power, which you have to do with a rohloff to shift smoothly.
The only answer we found was to call out every gear change to the stoker so that they could completely stop putting any pedal imput in and enable the pilot to ease the change .
I have since bought a sterling frame and moved over all the running gear to make a nice rohloff mountainbike.
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Thanks for the insight everyone, especially from tandemman. I will try backing off the cable tension, but I don't think there is much tension on it right now - only just enough to avoid having a sloppy feeling in the shifter, but no more. However, I'll try it with a sloppy shifter.
To answer other questions, yes this is a brand new Rohloff hub, so I don't think a double oil flush is really going to solve the problems. Tandems are almost always photographed with the pedals in phase (they do look better that way), so the pictures in Thorn's Raven brochure don't really offer any useful information.
Sending the hub back to Rohloff doesn't seem to be needed since it does work pretty good when riding the bike solo. If the choice is between using the Rohloff and setting the pedals in phase and using derailleur gearing and having the pedals out of phase, then I would opt for the derailleur + out-of-phase setup.
The gearing is a 42 tooth chainring with 15 tooth cog plus 700x28c tyre. This gives us about 7.5 kph at 80 rpm in bottom gear and just over 50 kph at 100 rpm in top gear - pretty good for a road tandem, although I would step it down a bit when we do some touring (42-16 or even 38-16 would be easy options). Our normal cadence is 85-95 rpm, with a maximum comfortable range of about 70 to 120 rpm, giving a current possible pedaling range of about 6.5 to 60 kph. As I said, I'm very happy with the range and it is extremely similar to our old derailleur setup (which was a 28-42-53 crankset plus 12-32 10-speed cassette, which could be dropped to 26-39-50 for touring). Direct drive (gear 11) is about 28 to 33 kph for us, which is a bit higher than I'd like, but if I drop this down to the 23-27 kph range that I'd prefer then we'd lose a lot of top-end speed.
Things are sounding more and more like I should get ready to build up that MTB. I already have a front and rear wheel, one disc brake, the gearing system (Rohloff), and seatpost - I just need a frame, fork, crank, saddle, and bars. However, we'll give the tandem a few more rides and see if we can improve it / get used to it, but it's not looking promising at the moment.
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Chris
If you are using the TS version of the hub (i.e. the version that isn't quick release) then there is some anecdotal evidence that if the axle bolts are tightened down too much then poor shifting will result. I have to say I am sceptical about this, indeed I would understand this advice more if it applied to the quick release version!
I haven't ever ridden a tandem, but I do have a fair bit of experience with a Rohloff. The only time I have a problem shifting is on the 7-8 / 8-7 shift and under load. As others have said this can be mitigated (on a non tandem) if you time the shifts to the low power part of the cycle stroke.
Anyway if you are using Axel bolts it would be worth slackening them off and seeing if there is a difference.
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I don't have quick releases anywhere on my bike as part of the systems approach to security, and because no flats are expected with the banded tyres I use. But my Rohloff isn't the TS either, it is the CC quick release version, but bolted on. That's an interesting point Stu makes. Unless you're pretty experienced (which I guess Chris is, not only a professional mechanic but head mechanic at a bike shop), you should use a torque wrench for tightening the bolt (and be very careful if you use a QR). The rating is only 6 Newton meters, easily exceeded even with a short-handled torque wrench. I'm sure Herr Rohloff wouldn't have specified it that low if it didn't matter. The SON dynamo hub, also familiar to many Rohloff owners, is specified for higher fastening torque, and so is the Shimano Nexus internal gear hub (I have no experience of the Alfine but imagine it as a beefed up Nexus, so probably unlikely to have lower fastening spec).
Oddly, I now can't remember whether I lift off when I change gear on the Rohloff, but then I'm not a scientific rider, just a recreational putterer. I certainly never lift off to the stage where it degrades my forward motion to the point of an irritation that I remember. But I do remember writing on this board that on an agricultural gearbox, which is how I described the Rohloff after the silky smooth Nexus boxes I loved, the gear change was tha crudest part, it was so rough and irritating. It probably hasn't become all that much smoother in 5000km, though some, but I became used to it, and the other benefits of the box (clean hands!) started to assume greater importance in my mind. It is, as has been suggested, a smart idea to give the Rohloff considerable time to rub in with you. Almost nobody but the trendies and the fashion victims like the Rohloff from the word go, but it is rare to find anyone with a few thousand clicks on a Rohloff who'll even consider going back to derailleurs.
On the other hand, it sounds like you're a pretty successful tandem pair on the derailleurs and so expert on them that, for you, it wouldn't be a hardship to return to them.
Andre Jute
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We have a Rohloff on our tandem and like you have the cranks 90 degrees out of phase for the reasons that you mention. I do find that we have to be quite careful shifting from gears 7-8, but find the best way is for me (pilot) to try to stop the pedals moving for an instance when they are flat (helps having SPDs, stoker at pedal up/down position). We have never had anything as bad as you describe in all the other gears, just the occasional refusal to change when I forget to ease off going uphill.
We've found that the Rohloff is more forgiving than derailleurs, it simply will not change if it doesn't want to, where as a derailleur would skip and normally end up with the chain coming off or crunching gears at the very least.
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Hi Chris, are you running full-length Rohloff cable housing?
You say the shifting "shifts fine when on the repair stand, and reasonably well when riding the bike solo". Can you compare the shifting performance and feel to a normal, i.e. non-tandem shifter?
Thanks,
Ewen.
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The only time I have a problem shifting is on the 7-8 / 8-7 shift and under load.
Funny thing - I only have any rough shifts going from 8-7. The shift up from 7-8 is as smooth as all of the other gear shifts with the Rohloff, no need to back off power at all.
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Funny thing - I only have any rough shifts going from 8-7. The shift up from 7-8 is as smooth as all of the other gear shifts with the Rohloff, no need to back off power at all.
Same here.
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Dan I have slightly modified this post to fit in with the split in topics
Hi All,
SWC, running a tandem with Rohloff is less common among Forum members than single bikes with Rohloffs. You probably have more experience doing so than the rest of us, and you've mentioned you ride that bike more often than the derailleur tandem you also own.
Efficiency comparisons aside, you mentioned your Rohloff shifts are "quick and positive", unlike the OP's experience. Lets see if we can find something in that which could prove helpful to the OP...
Crank-phasing proved problematic for him in shifting.
Can you tell us if your tandem's cranks are in-phase, or out-of-phase? If the latter, by how much?
He found it difficult to shift under the continuous load placed on the drivetrain by having the cranks out-of-phase (which he preferred). Can you tell us a bit more about your shifting technique (i.e. shifting under load vs backing off a bit while making the gear change) that has proven successful for you?
Can you tell us if you are using a Rohloff with q/r, or with nutted axle? Axle tension may have been a factor for the OP as well.
Whatever, your Rohloff is working well for you, unlike the OP. Perhaps there is something in your experience that can help him achieve his goal of getting a tandem with Rohloff drivetrain to work for his needs. Though the Rohloff has proven less efficient for you, you still prefer it over the derailleur model for reasons already stated.
Debates concerning Rohloff vs. Derailleur efficiency would better take place in the thread already devoted to that topic, here: http://www.thorncycles.co.uk/forums/index.php?topic=4073.0
Debate on Rohloff vs. Derailleur efficiency in Tandems has been moved into Rohloff Efficiency on a tandem (http://www.thorncycles.co.uk/forums/index.php?topic=4337.0)- Stutho
Best,
Dan. (wearing his moderator helmet)
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Thank you Dan.
Our tandem cranksets are in-phase and our Rohloff has a quick release axle. I included a link to photos of the bike in my first post which show how it is set up.
There are a couple of factors with tandems as opposed to single bikes that make shifting a Roholff more difficult: One is that with the increased weight and power applied, tandems put more load on the hub. The second is that it's difficult to get two people to back off at the same time during the shift. Don't get me wrong, not all shifts are quick and positive; only good ones, which is most the time. As I stated before, shifting is more difficult as the load increases, so I try to maintain a relatively high cadence and light-to-moderate pedal pressure. Shifting at the right time is a matter of experience and I don't always get it right. Usually what happens when I get it wrong is that it will require more force and I will over-shift, going two gears instead of one. If I wait until the load is high it can take a lot of force to make it shift. Perhaps part of the reason that we experience slower overall speeds on the Rohloff tandem is that I practice more "pre-emptive" shifting; that is - as we approach inclines I tend to shift early to avoid being stuck in a situation where I can't make it shift.
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Andre I have slightly modified your post due to the split of topic - stutho
The important thing about a newish Rohloff is that the change is miserable. Though I admired the concept of the Rohloff, and had extensive familiarity with hub gearboxes, when I first acquired a Rohloff (in an admirable installation by the manufacturer who was the first to adopt Rohloff as an OEM box), I brassed off some people here by describing it as "agricultural". It was some thousands of klicks before the box smoothed out enough to be forgotten, and I don't think it will ever change with the jewel-like precision of Shimano's Nexus. Despite this, I am as convinced as any of the other aficionados here that I spent my money wisely when I bought a Rohloff. Though I have zero tandem experience, it seems pretty obvious to me that the length of cabling on a tandem will aggravate the baulking of a new Rohloff box. It's just one of those things that you have to live through, like a new Brooks saddle not being as comfortable as you hoped for a thousand miles or more. (Buy a B73, the triple coil spring one, they're comfortable straight out of the box.) I think you're probably still a 1000km away, SWC, from having a Rohloff box smooth enough not to notice its changes. Then one day you wonder what the fuss was about.
Chris's problem is at an altogether different level.
Andre Jute
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I would never have characterized the Rohloff as agricultural, although it is a relief to hear someone say that switching to a Rohloff is not all sunshine and fairy dust. The shifting has never been balky, but because of the necessity of play in the cable I find that I can't just grab the shifter and turn it. I usually have to turn the shifter until I feel tension in the cable and then shift. With the derailleur tandem we could build up speed prior to a hill and using our momentum pedal until we could hardly turn the cranks anymore before shifting. The Rohloff won't shift under those conditions, requiring me to shift earlier thus losing momentum on the climb. The noise that many people find objectionable has never bothered me. I've read some people describe it as a "grinding" sound whereas I would call it a "whirring" sound, not unlike the old bottle generator I had on my bike as kid. Besides, on the tandem it's so far behind me I hardly hear it anyway. As far as break-in is concerned, I would think that due to the higher loads that a Rohloff would encounter in tandem service it would break in fast than a single bike. 1000Km is only, what, 620 miles? I suspect that it will take another couple of thousand mile before it's completely smooth. (I'm an American, I don't speak metric. :))
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I have the impression that Rohloff changed something in their manufacturing so that hubs produced in the last years make less noise and have better (but not perfect) gear shifting when new than the hubs produced during the first years of production.
The shifting indeed requires more and more power when more power is applied on the pedals. We have a special tandem with a freewheel and not unity ratio of the stoker-captain transmission equiped with Rohloff, so the phase changes. When cranks are not in phase, it is more difficult to shift unless the shift occurs when the stoker is at the dead point and the captain interrupt his load on the pedal (which is possible since the captain is at the rear and sees the stoker pedaling). Having the crankset with a fixed 90 degre phase difference is I think a kind of worst case.
I think also that the Rohloff experience will depend of the type of tandem and usage. A sport oriented tandem and usage will probably give a worse experience of the Rohloff gear shifting than a touring/travel tandem.
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This topic has been split into Two. Please also see Rohloff Efficiency on a tandem (http://www.thorncycles.co.uk/forums/index.php?topic=4337.0)
I have tried to maintain the integrity of each.
Best regards
Stuart