Thorn Cycles Forum
Community => Rohloff Internal Hub Gears => Topic started by: georgeidf50 on November 03, 2005, 11:02:11 PM
-
Why oh why does the crank spin when I push my Catalyst with Speedhub14
By the way I am on South american ripio ( gravel and mud) roads in the Andes with a 45 kg BOB Ibex trailer, so I push quite a bit and the cranks keep spinning.
The pedals go into the back of my knees and cripple me
why oh why
george
-
This happens to me too.
The back of the knee or the ankle blows are particularly painful.
The Rohloff manual says to try dropping some Rohloff cleaning fluid into the hub and Thorn told me to hit the axle with a rubber mallet but neither of these things have worked for me.
I hope one of these might work for you.
Does anyone have any other ideas for me?
Anthony
-
So I guess this is a problem with the freewheel mechanism?
Interesting. This isn't a problem with the hub I have read about before.
Does it help if you put it into a different gear?
-
Changing gears only changes the rate at which the pedals spin.
-
What age are your hubs?
Mine did this till I'd done around 3,000 miles then it stopped doing it. Nothing else has changed.
-
mine is 11 months and more than 3000 miles old but the problem persists
Anthony
-
Come to think of it mine did this once or twice in its first year but hasn't happened for a long time now.
-
I have two Rohloff hubs and both do it.
The one currently in the Raven tour has about 4800 miles on it, but it did most of those in the tandem.
The new hub in the tandem is about 2000 miles old.
Personally I'd previously put it down to an apparently robust nature of the freewheel creating more drag than you'd see on a derailleur equipped bike.
But thinking about it as I write this, I suspect it's probably mostly because there's no chain tensioner arm with a Raven. The drag caused by that on a conventional bike is probably greater than the drag caused by the freewheel, so the chain doesn't move. On a Raven, the bottom bracket may well spin easier than the freewheel, so that's the bit that moves. For those of you who don't see the effect, maybe your B/B is a bit stiffer than some.
I'd confirm that the rate varies with the gear you're in. I'm not sure how that fits with the above theory, but I don't think it necessarily invalidates it.
Personally, I walk with the bike leaning a bit or at arms length so the pedals can't get me, and don't see it as much of an issue.
-
Everyone here seems to be talking about new hubs (all under 5000 miles old).
The first oil change happens after 5000 miles or 1 year so I wonder - because of the lack of postings from people with older bikes - if this might solve the issue for us.
BTW Thorn has some new advice on Rohloff oil changes. Check:
http://www.sjscycles.com/thornwebsite/rohloffhuboil.html
Anthony
-
quote:
The first oil change happens after 5000 miles or 1 year so I wonder - because of the lack of postings from people with older bikes - if this might solve the issue for us.
No, 5000 Km. 3100 miles.
My hub with 4800 miles on it had the oil change some time ago now.
Actually, we rode the tandem again today and on the small bit of pushing the cranks did not go round. Probably because of the extra chain and two sets of rings and two bottom brackets overcoming the slight drag from the gearbox. This hub now has just under 2100 miles on it. And hasn't had the oil change yet.
-
Just dug up this ancient thread and it attracted my attention as it appears some people's cranks stopped spinning after their hubs had done such and such number of miles. I've done two oil changes (both were slightly overdue...) and my cranks still spin as robustly as ever when pushing the bike.
Anybody's hub bedded in in such a way that this phenomenon has stopped for them?
-
After 21,000 km on my Raven Tour it comes and goes. It is possibly a little bit reduced from when the bike was new.
Peter
-
After 21,000 km on my Raven Tour it comes and goes. It is possibly a little bit reduced from when the bike was new.
Peter
Similar here, I think (because I don't really notice it any more)
-
To all guys with spinning crank: does your bike own achain tensioner or not?
If yes - the crank may not spin
If no - the crank may spin in some gears. Important is the correct chain tension.
-
To all guys with spinning crank: does your bike own achain tensioner or not?
I think we're mostly talking about various Thorn Ravens here so no chain tensioners.
I, for one, like to believe that my chain tension is perfect ::) but even when it has been less-than-perfect (lazy days...) the cranks have spun so I don't reckon that's a factor, though I can see how having the tension too tight would mean they don't spin.
The cranks spin in all gears when pushing. Have you noticed a difference between gears, Almeida?
-
Yes, my bike too still has rotating cranks after 20,000+ kms. Which is a bit of a peave when my wife's bike has stopped doing it at less than 4,000kms.
Having said that for me it is not that much of an issue as I rarely have to push my bike anywhere.
-
The cranks spin in all gears when pushing. Have you noticed a difference between gears, Almeida?
Of course there's a difference between the gears because of the engaged parts inside the hub. Like the different gears have an effect to the working efficiency.
Try gear #5. I guess there are most parts working. Pedals shouldn't spin ( max. a little bit, without great force). May depend on the condition of the bottom bracket.
Otherwise the hub is too stiff and you should make an oil change. Maybe it's better then.
-
Gear #5: cranks still spin merrily and I did an oil change last week (or the week before maybe... anyway, not long ago). At the time I also fitted new cranks and BB.
Occasionally I'll batter a shin/calf with a pedal when pushing the bike or, more frequently and more annoyingly, dig myself in the guts or spine when carrying the bike up or downstairs and the rear tyre catches a step/wall/bannister.
But hey ho, I know there's nowt wrong with the hub, and I know the pedals spin when the rear wheel goes round, so any injuries so caused are then down to user error. Based on Stu's experience of 20,000km and the pedals still spin, it doesn't look like it's going away so I better just get used to it.
(Though weird that your wife's stopped doing it after 4,000, Stu...? Different BB...? Bizarre!)
-
Gear #5: cranks still spin merrily and I did an oil change last week (or the week before maybe... anyway, not long ago). At the time I also fitted new cranks and BB.
Occasionally I'll batter a shin/calf with a pedal when pushing the bike or, more frequently and more annoyingly, dig myself in the guts or spine when carrying the bike up or downstairs and the rear tyre catches a step/wall/bannister.
But hey ho, I know there's nowt wrong with the hub, and I know the pedals spin when the rear wheel goes round, so any injuries so caused are then down to user error. Based on Stu's experience of 20,000km and the pedals still spin, it doesn't look like it's going away so I better just get used to it.
I'm fairly sure that there is a failure inside your hub.
-
I'm fairly sure that there is a failure inside your hub.
What??? Does that mean that loads of us on here have a failure as we've all had the cranks spin when pushing the bike?
Erm, I'm not sure about that. The hub works perfectly and having the cranks spinning when I push the bike along is nothing more than a very minor inconvenience. If the spinning was accompanied by weird noises and slipping gears I'd be worried.
Thanks for your concern and help though, Almeida!
(I should perhaps clarify and say that the bike doesn't behave like a fixed gear or anything like that, the times when the pedal catches me is s just a case of me not realising exactly what position the pedal is in at every moment.)
-
Jawj,
My wife and I are on the same BB. I suppose it is possible that my hub is faulty - but I doubt it. I will just but it down to manufacturing variance. It is also possible that the manufacturing processes at Rohloff have being perfected over the last few years.
When I bought it My hub was second hand. At that time it hadn't seen many mile but was it was a year or two old, so that would make it 4 to 5 years old now. I know the way they seal the hubs has changed in that time - maybe there are some internal differences as well. I do Know that wife's hub (just over one year old) got quiet a LOT faster than mine. Both are pretty silent now out of the two hers is the quietest - mine is audible in gear 7 and just audible in 11. Both hubs have had regular oil changes.
I am sure that for off-roaders this is a pain but for me I never notice it (As I ride everywhere and rarely push)
-
My was never a 'pain' until I moved into the flat I'm in now with it's tiny little staircase...
Phew, spinning cranks is normal. let's lay this one to rest.
-
Phew, spinning cranks is normal. let's lay this one to rest.
O.K. I've to admit that is the easiest way for you. But aren't you curious whether there is a failure or not on your hub? ???
I can't be sure that I'm right with my claim about the failure because I don't know your bike but I would suggest to research all facts. Maybe it is possible for you to compare your hub with another hub (store, friend...)
Dismount both rearwheels, shift in same gear and twirl the sprockets backwards. Compare the resistance.
Sorry for worrying you ;)
-
push :D
-
It can be caused by a few things:
i. Running your chain too tight
ii. The sprocket sticking in the drive side seal (hence Rohloff's suggestion to add a few drips of cleaning oil
iii. Bits of spring, cotton, sheep etc, ever noticed how that sort of stuff manages to get itself wrapped around sprockets?
iv. The internal shifting in the hub (hence Rohloff's suggestion to hit the non drive side axle end with a soft faced dead blow mallet)
In practice if yours is doing it and you want to try and stop it,
1. Remove your sprocket
2. Clean the seal lip and add some lubricant
3. Clean the sprocket and refit (the same way round!)
4. Give the axle a sharp whack
5. Back the eccentric off a bit, the chain dosn't need to be bar tight, just tight enough that it can be derailled
Hope this helps :-)
-
Take my sprocket off again!?!? I just had a heck of a job taking it off the first time...
Is the minor problem of the cranks spinning enough to justify giving myself another hernia?
But seriously though, thanks Dave, for your very helpful and complete suggestions as to how to sort the problem. I made indeed try whacking the axle - percussive maintenance is always good fun!
Thanks again for your concern, Almeida, I am definitely curious about if there is a failure in the hub. What makes it curiosity rather than concern is the fact that the hub works absolutely perfectly all the time in every way: shifting, pedalling, freewheeling. Since the hub is not malfunctioning during use, and I'm not alone in experiencing the cranks spinning, I'm not going to worry very much about it. Thanks though!
-
Hope this helps :-)
...and if not ???
I'm not going to worry very much about it.
Great. Have fun. Let's go riding. Talked more than enough.
-
Hi Dave,
Very good advice, unfortunately I have tried it all before. At lease twice! I love my Rohloff and the rotating cranks don't put me off in the slightest - it just a bit odd.
-
This is one you have to look at logically, the only two faces that actually touch each other that would create forward motion to the crank REGARDLESS of what ever gear you are in, is the main hub lip seal rubbing on the outer diameter of the output gear. The reason that whatever gear you are in doesn't matter is because the rohloff hub is a rotating mass when being pushed or in freewheel, therefore gear selection has no relavance, the factors that will alter the amount of friction created by the hub and gear is, the size of the output gear(SPROCKET) in terms of teeth, the size of the crank chain wheel, the amount of tension on the chain,(and contary to popular beleif the tighter the chain the less the problem the slacker the chain the more highlighted the problem(tight more friction)(slack less friction) for the sprocket to fight against, and finally the amount of friction in the bottom bracket bearings, because there are so many differing factors this is why some people are experienceing the problem and others are not. In answer to the person that suggested that the hub was faulty in their veiw as it was not a problem that they has encounterd you could argue that the friction of their lip seal was not as much as yours and infact it was their non rotating crankshaft that had more of an issue than yours, in as much as to say your seal has more of a sealing effect than the one being created by theirs.
-
It can be caused by a few things:
i.iv. The internal shifting in the hub (hence Rohloff's suggestion to hit the non drive side axle end with a soft faced dead blow mallet)
In practice if yours is doing it and you want to try and stop it,
4. Give the axle a sharp whack
5. Back the eccentric off a bit, the chain dosn't need to be bar tight, just tight enough that it can be derailled
Hi Dave, I thought the idea of giving the non drive side a sharp whack was to eleviate internal stress on the bearings caused when the hub has been split and rebuilt. What happens is the final drive output that locates into the main hub is not pushed home fully by the T20 hub flage screws, which is why the sharp whack is required to bring the shaft and internals back into place. The tell tale sign of a stressed hub is the lack of freewheel when the wheel is spun. I'm confident that this would have nothing to do with the crank's being propelled by pushing or free running. Also you mention that the chain tension being to tight can cause the issue to be more adverse, of which I disagre. The chain being tight would actually create a greater amount of friction for the sprocket to turn and by making it slacker would only encourage the issue to be more apparent.