Thorn Cycles Forum
Community => Rohloff Internal Hub Gears => Topic started by: IronMac on March 15, 2014, 09:17:51 PM
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Hi all,
Not sure if this topic is specific to the Rohloff but a mod can move it if necessary. After reading through a few threads/posts I purchased a couple of KMC 8-99s to replace the KMC Z-50 on my Bike Friday NWT.
BF says on the invoice that the Z-50 is an 8-speed chain and the US KMC site says that the 8-99 was both 8-speed and IGH compatible. The size of both chains are the same as are the number of links.
So put a 8-99 on and it skips intermittently. Checked for stiff links and did not find any. Put the other 8-99 on and same problem. Put the old Z-50 on and it works even better than before.
Can anyone tell me where I went wrong? Thanks!
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New chain, worn sprocket, perhaps?
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Hi welcome to the forum, I suspect your chain and sprockets are all worn at the same rate so you most likely need some shiny new sockets as well.
How old are sockets
Have a look at the tooth profile and check them against some pictures on the internet.
Peter
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Oh sorry...should have pointed out that the sprocket is perfect...it has about 5k kms on it...maybe.
I only ride on dry roads every weekend. No need to ride in the rain or muck since I can't go touring. Also, clean the drivetrain about every couple of months with degreaser, brush, then oil again.
And switched out the Z-50 only because two rulers said it was stretched.
Edit: phopwood, thanks for the welcome!
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The next check should then be your chain tension, but I would expect the new chain to be tighter than the old one.
Post some pictures if you have any.
Peter
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Tooth no. of your sprocket? A small sprocket could wear at a much faster rate such that 5,000 kms may be enough to cause wear. Maybe....
The only way to really confirm is to get a new sprocket and fit it with the new chain. My guess is that they will then run fine.
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Tooth no. of your sprocket? A small sprocket could wear at a much faster rate such that 5,000 kms may be enough to cause wear. Maybe....
The only way to really confirm is to get a new sprocket and fit it with the new chain. My guess is that they will then run fine.
It's a "15-tooth cog" according to the invoice.
The teeth of the sprocket look fine and I've seen pics of worn down teeth. It should last for over 20,000 kms, right?
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Is it a double-sided sprocket, or is the 15t the single-sided one?
Meh...... well, I have swapped my sprocket around at 12,000kms I think (17t) and will replace everything at ~24,000kms. So that will be the sprocket worn out on two sides. Your sprocket *should* last more than 5,000kms, but it really depends on what the chain is like. Place the chains together and measure 12" (24 links). If the old chain has extended to 12 1/8" or more for 12" of original links, the sprocket will be worn to the point that a new chain will skip. Your old chain doesn't skip because it is worn to fit the sprocket.
Oh, yes, the original chain - KMC Z50. A quick search and glance at the pictures, this looks to be a fairly budget-oriented chain. I would not be surprisded that it wears out (and the sprockets) at a quicker rate.
My prediction, as I said, is that a new sprocket will run fine
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Is it a double-sided sprocket, or is the 15t the single-sided one?
Meh...... well, I have swapped my sprocket around at 12,000kms I think (17t) and will replace everything at ~24,000kms. So that will be the sprocket worn out on two sides. Your sprocket *should* last more than 5,000kms, but it really depends on what the chain is like. Place the chains together and measure 12" (24 links). If the old chain has extended to 12 1/8" or more for 12" of original links, the sprocket will be worn to the point that a new chain will skip. Your old chain doesn't skip because it is worn to fit the sprocket.
Oh, yes, what was the brand/model of the original chain? This can lead to varied wear.
My prediction, as I said, is that a new sprocket will run fine
The 13t is the non-reversible one.
The original chain is a KMC Z-50.
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Hi Mac, and welcome to the Thorn Cycling Forum!
I was out riding today when I saw your post and so had some time to think on it before replying.
I live in Eugene, Oregon where Bike Fridays are made, and dropped by the shop again several weeks ago. I have seen several Rohloff-equipped New World Tourist BFs and noticed each of them used a chain tensioner.
By any chance, could the chain tensioner have been bumped or changed tension when you replaced the chain or when the bike was un/folded? If so, this could account for the occasional skipping, quite apart from the condition of the chain. This happened to a former listmate of mine on a different forum; he worked for BF at the time and built one of the early Rohloff versions for himself. He found without the tensioner or with it set slack, there was insufficient chain tension to prevent occasional skipping.
Though it seems an unlikely contributor, it might be worth checking your chainline. I recall reading reports indicating the KMC 8-99 is more picky about such things in fixed-gear and single-speed applications than the Z-50.
Hope this helps. Please let us know how you come out.
Best,
Dan.
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If the sprocket is double-sided your answer is easy - turn it around. Later, when the new chain has worn out a bit, you could even rotate it back to get the last bit of life out of it.
Dan's idea about your chain tensioner is worth double-checking too.
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Hi Dan!
Thanks for the welcome!
Yes, my first thought when I got off the bike by the side of the road was the tensioner but when I got home both the Park Tools BBB and Rohloff manual said stiff chain link so the chain (and sprocket) has been where I've been concentrating my efforts. The chain tensioner is the same as it has always been so far as I know since you have to take out that "tensioner spring" in order to de-tension it (fully?). It is a regular Chain Tensioner and not the DH Chain Tensioner.
I've been looking for ways to adjust it by small increments but so far no luck.
il padrone:
Hope this sprockets pic helps..
(https://lh4.googleusercontent.com/-M_c3zGazfE0/UyUuOklmEhI/AAAAAAAAAJ0/G6fse63zdHM/w925-h694-no/Rohloff+sprocket.jpg)
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Frankly, I would hate for it to be the chain tensioner because just by looking at the online pdf, you need to adjust it by shims and have to measure everything in millimeters. I mean, come on! :o
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Check the jockey wheels are smooth they have a habit of locking up on the tensioner. Also we have talked about the rear sprocket what about the chain ring how does that look.
Peter
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Doesn't appear from the photo that a worn sprocket is the problem here.
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How have you joined the new chain? Quicklink or re-inserted rivet?
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Check the jockey wheels are smooth they have a habit of locking up on the tensioner. Also we have talked about the rear sprocket what about the chain ring how does that look.
Peter
Jockey wheels look good but I would have to take the chain off in order to spin them by hand. I clean those little guys by hand since it is easier for me to get in there with a piece of towel to scrape every tooth.
Chain ring looks good too but I have nothing to compare it against. All teeth are accounted for...no one tooth seems too sharp or too short.
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How have you joined the new chain? Quicklink or re-inserted rivet?
All chains done with quicklinks or whatever KMC calls them...Masterlinks?
At the side of the road, in addition to thinking it was a tight link I also looked for any pins that might be protruding. I saw one that was out a couple of millimeters so I whipped out a chain tool and gently nudged it flush with the rest of the link. No effect.
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Doesn't appear from the photo that a worn sprocket is the problem here.
Heya! Aren't you also on Bikeforums.net or Bikeforums.com? The name is very familiar.
I'm preparing an order for sprocket replacement just in case...
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Heya! Aren't you also on Bikeforums.net or Bikeforums.com? The name is very familiar.
I was in the newsgroup RBT in the great days when Jobst Brandt, Sheldon Brown and Chalo Colina were there. Since then it has been taken over by the vehicular cyclists, the anti-helmet zealots, and mindless political spammers, so I generally give it a miss and instead make my cycling home here. Perhaps you saw my bicycle pages on my netsite http://coolmainpress.com/BICYCLING.html or perhaps you just saw my books or my journalism.
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make my cycling home here
For which, Andre, we're thankful. :-)
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I hope you don't mind me mentioning, Andre, another of your realms:
http://www.goodreads.com/group/show/46791-robust (http://www.goodreads.com/group/show/46791-robust)
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Hrmm...I don't know about newsgroups since when I was on there in the early '90s I was not in any bicycling ones. But Andre Jutes is very familiar for some reason...
Anyways, back on topic...could it be the chains themselves?
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For which, Andre, we're thankful. :-)
You're so gracious, John. It's great to be with agreeable, knowledgable people.
I didn't know you visited ROBUST, Jim. You should contribute. Everyone who's interested is welcome. https://www.goodreads.com/group/show/46791-robust
Mac, if you were into tube audio and high efficiency loudspeakers in the 90s, you'll know me. http://www.audio-talk.co.uk/fiultra/JUTE%20ON%20AMPS.htm
About your chain, it's most unlikely that both your chains should be faulty. If the teeth on the chainwheel are good, if the chain line is straight enough, if the chain has no stiff links, then all that is left is the tensioner, and if it worked before, then you must have disturbed something when you fitted the new chain. Were my bike, I'd count the links very carefully; it is easy to measure two chains of equal length and then to fit the new one with a quick link from the packet without noticing that it is in fact an extra link.
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Were my bike, I'd count the links very carefully; it is easy to measure two chains of equal length and then to fit the new one with a quick link from the packet without noticing that it is in fact an extra link.
Bingo!!!
That is not exactly what happened but I was desperate enough to decide to take off the old chain and lay it side by side with one of the new 8-99s to see if there was an extra link or MissingLink.
It was immediately apparent that the new chain is much LONGER than the old one. Bike Friday had snipped off 10 links off of the old Z-50!!!
This may explain why the KMC European site says that their high-end IGH chains have 110 links...guess you could always snip off a couple to make it fit.
So, before I go and snip off ten links...any objections or gotchas? Thanks!
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I always remove a bunch of links from a new chain to get it to fit my Nomad correctly. Ought to be a routine operation.
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Measure twice cut once, is my only advice.
Peter
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Measured and counted three times!
Well, some joy. The skipping has really cut down but in a very short 5 min ride (it's pouring outside right now) it skipped about 9-12 times. And it did not skip in all gears as it did before. And it seemed to skip in certain parts of the cadence or revolution.
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Sounds like you are nearly there.
Do you now have the same amount of links as the old chain, if you do I would look at the tensioner spring. Can you take a picture of the whole drive including Tensioner, rear and front sprockets.
Peter
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12" of chain on your new chains will be 24 links. Have you measured those 24 links on your old chain? Was it under 12 1/8", or more than this?
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phopwood: Yes, same amount of links as the old chain.
il padrone: the old chain was over 12 inches...maybe 1/8 over...and I used two different rulers to measure stretch.
here are some pics of the current setup and it is gear 6 according to the shifter.
(https://lh6.googleusercontent.com/aC90e-2XjBrqaU6bNOTRrLcdPBzWJpni52YkBA8clME=w262-h196-p-no)
(https://lh3.googleusercontent.com/HWCbd5w-mEzkWMQPNC0A4F8y5BdIHxxWUxjGWI6b3nc=w262-h196-p-no)
(https://lh5.googleusercontent.com/lRa3rWTuuw2MUoOX7JO3h2MpuywndvfQ0Q-t5njsC2k=w263-h196-p-no)
(https://lh4.googleusercontent.com/UdZUHxniy9J6uZTQn6JGGjre00HCKPeYbkjPWORFN2A=w263-h196-p-no)
(https://lh4.googleusercontent.com/kCuR8CnPryrsLOag4bdSZN8ai_oxLMYkL4Orsc_ZmVM=w155-h207-p-no)
(https://lh4.googleusercontent.com/Sea7PmnpN_E8xrX4KcY5Fc9BSgH11JXvirq__o-rWfA=w155-h207-p-no)
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From a visual point of view all looks ok, I can't see the chain line, but if the chain line is out, on the tensioner you will see wear lines on the inside of the tensioner where the chain rubs..
Can you describe the skipping.
Also how tight is the spring on the tensioner, push the tensioner up towards the chain stay and see how tight it is.
Peter
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Ok, no wear lines anywhere that I can see. I shone a flashlight down starting from the sprocket and followed the chain through the flywheels and out. The chain does not rub against anything so far as I can tell.
The skipping is usually a one or two skip where it seems something has not caught and it occurs only when you're really putting some pedal to the metal.
And I can't budge the tensioner. It's rock solid from the left, the two holes, the nut or bolt, down to the wire. The only part that can be moved is the hanger with the lowest flywheel. Even then, pushing upwards to move the hanger you are in danger of tipping over the whole bike.
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Hi,
I confess without seeing and playing with the bike I am stumped.
If you can rotate the pedals forwards with the bike supported in some way you may be able to see why the chain is skipping.
It might also be worth checking your hub shifter tension just in case your hub is causing the problem. But if it was the hub I would expect a slip rather than a skip.
All the best.
Peter
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Thanks Peter for the effort.
I may have to email Rohloff with a link to this thread to see if they have a suggestion.
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It does sound like a new chain on an old sprocket. My current chain started off noisy and then moved into just shifting a bit under load and now all the parts have worn themselves into compatibility. The whole process took a few hundred miles.
If you're talking about little shifts, like the pedals move a quarter inch, I would say just keep riding and see how it evolves. If you're talking about big shifts, where the pedals move maybe 30 degrees or more around the circle, that would not be a worn sprocket and would seem to require more attention.
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Thanks Jim for the latest reply and it concurs with what Rohloff just emailed me back. They are pretty sure that the sprocket has worn just enough for there to be an incompatibility issue.
Thanks everyone for taking the time and making the effort to help me with this.
Will report back when all of the stuff arrives.
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Mac, did you ever get this all sorted out.
Peter.
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Thank you Peter for the question. I was hoping that I could report success but here is what has happened.
I finally received a sprocket three days ago because Bike24 was moving their warehouse and held up all orders by over a week. It then took its own sweet time to arrive here in Singapore.
I had ordered a 15 tooth sprocket because that was what was on my Bike Friday invoice. Lo and behold! They had installed a 13 tooth sprocket! :o
Grrrr.....I could not believe it! They only build bikes with 20-inch and smaller wheels yet they put down a 15 tooth sprocket on the invoice! I had seen mention of the 13-toother for 20-inch wheels but thought that BF knew something that I did not.
Can I still use the 15-tooth sprocket? I don't know if it will overstrain the hub or not. According to BF's invoice, the front crank is a 53-tooth but I would take that with a grain of salt.
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Hi Mac!
I'd suggest counting the teeth on the chainring first so you'll know for sure what you're dealing with in choosing your ratios.
Here's Rohloff's take on the matter: http://www.rohloff.de/en/technology/workshop/sprocket_ratios/
Smallest permissible sprocket ratios
The primary sprocket ratio used with the Rohloff SPEEDHUB 500/14 (e.g. 42:16) converts the slow rotational speed at the crank into a fast rotational speed at the rear sprocket and reduces the input torque for the Rohloff SPEEDHUB 500/14 in the same proportion. To prevent overstraining the hub, a minimum factor of 2.10 must be used. This minimum factor equates to a primary transmission ratio of:- 36:17, 34:16, 32:15 and 28:13. These SPEEDHUB 500/14 ratios resemble a derailleur transmission of 20:34.
Larger chainrings can be used without exceptions.
A 53x13 gives a ratio of 4.07. Used with 406mm wheels, the range will be from 21.2-111.7 gear-inches.
A 53x15 gives a ratio of 3.53. Used with 406mm wheels, the range will be from 18.4-96.8 gear-inches.
In answer to your question...Can I still use the 15-tooth sprocket? I don't know if it will overstrain the hub or not.
I think you'll be fine.
Best,
Dan. (...who lives on the bike route about 2mi/3.2km from their factory door so sees a lot of 'em)
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As Dan says I think you will be fine. Let us know how it goes.
Peter.
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I'd suggest counting the teeth on the chainring first so you'll know for sure what you're dealing with in choosing your ratios.
Hahahahaha (bitter laughter here)
The NWT has developed a metallic "shushing" sound while pedalling after the mucking around. Pretty sure it is not serious but it is going back on the stand and I will install the new sprocket then. Assuming of course that it is a 53-tooth chainring and not some weird-a$$ number.
So far, this bike has turned out to be a hangar queen. If it is not the Rohloff, it is the pedals; if not the pedals, it's the Supernova wiring; if not the lights, it's the Chris King headset; if not the headset, it's the fenders, etc. It's worry upon worry upon worry about what's next to fix.
Thanks Dan and Peter!
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A 53x13 gives a ratio of 4.07. Used with 406mm wheels, the range will be from 21.2-111.7 gear-inches.
A 53x15 gives a ratio of 3.53. Used with 406mm wheels, the range will be from 18.4-96.8 gear-inches.
Not only can you use the 15T sprocket, Mac, you should. Nobody needs a 112 inch gear on a Bike Friday, whereas the 18.4in low with the 15T sprocket will be rather useful on utility bike even in Singapore.
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Sorry to keep everyone in suspense but I was finally able to ride the bike and it's a success!!! Woohoo!
Changing the sprocket was a bit tough and I think it's because there was no grease in the threads. Well, at least none that I could detect. I also did not want to bang my knuckles while kneeling over the small wheel. But off it came in the end.
The ride now is silky smooth, there is hardly a sound and I keep thinking I need to get my hands on what KMC is using to lube up their chains! Shifting is excellent. As an aside, my hub makes very little noise and it's been that way for the longest while.
Thanks everyone for your input...much appreciated! :)
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That is great news week done to you, one less thing to worry about.
When was the last time you changed the oil on the hub.
Peter
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Thanks Peter!
Oil was changed in January or February. Ordered in the two jug offer (of cleaning oil and oil) from Bike24 so I am good for quite a while. Also have extra drain plugs but since I have a Loctite analog (German brand but not Loctite) I don't think I will need them for now.
Am disappointed to find out from this site that the KMC chain lube is a secret formula. I am really in awe of how all the rustling from the earlier chain has gone away. Wonder if it is some sort of nasal sebum? hehehe