Bicycle Mechanics - chris king hub/drivetrain help. please!!!!
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i have chris king iso hubs with xt stuff. the hubs recently got to their "break in point" so i adjusted them from having side to side play to being perfect (id say). i also threw on a new chain as my old one was a lil past the .75 mark on the gauge. but im nice to my stuff and know how to work on it so the cassette and chainrings arent too worn. heres the dilemma: in a majority of the gears when i freewheel/pedal backwards the chain becomes sluggish and there becomes extra slack in the chain and it (in most gears) eventually rides of the cassette, going to a larger gear. it also shifts a bit clunkier in the rear.
heres what ive done to remedy it:
-made sure the der. hanger was straight
-tried to use the old chain to see if it was the new chain meshing wrong- it still did it
-cleaned the cassette and freehub body
- overhauled the jockey wheels
- did a minor overhaul on the king hubs with ringdrive lube etc (but theyre only 4 months old and have been ridden with care over that period)
- tried to put the hub at the same preload it was at before i adjusted the hub (it was a tad loose) when it was not doing this- it did not fix the problem.
- cleaned the factory lube off my new chain in case its viscosity was causing the problem- still nothing.
- gave up after a day of screwing around and went to a mechanic at a good local shop- i think he knew less than me (ive been working in a shop for 3-4 years) as he said the drag in the hub was causing it, yet he says hes never worked on a king hub- they have a bit more drag than other wheels, but that does not limit them from spinning well etc. he had no suggestions besides bring it back for the head mechanic monday (i think i know about as much as him)
DO YOU HAVE ANY REMEDIES???? i think im a good mechanic and i have had to admit defeat. the only thing i have not tried is new c-rings/cassette but i doubt its that- it shifts well (albeit a tad clunky- but i like perfection). Help me please!!! im going to ask everyone at punk bike tomorrow but i doubt well be able to figure out a drunk solution.
thanks in advance, and if i missed an old post please share it with me.
First isolate the actual cause the problem. Yes there's some friction, but is it in the freehub or between the chain and sprocket.
Spin the wheel (coasting) and see if freehub friction causes slack in the upper loop. If not, the hub is definitely not the problem, and you can focus on the chain. Double check by seeing if you get the same symptoms when backpedaling in an aligned combination such as outer chainring with the 3rd sprocket.
If the bike passes both tests, it's a simple case of chainline and chain/sprocket friction. It isn't a matter of concern, but you can probably improve on it with some chain lube, and next time around looking for a chain with more bellmouth on the inner side of the inner plates. That will act like a funnel helping the chain to pick up the sprocket when feeding from an angle.
If it turns out to be within the hub, check with CK customer service, or repost and maybe someone more familiar with CK hub service can help you.
12-05-10, 01:03 PM
I owned a king hub for years, and serviced it extensively- usually after the symptoms you describe appeared(every one or two seasons). The key to servicing is the cleaning. What I found works best is using a no-residue spray solvent (such as white lightning clean streak) with the provided tip to really get into all the crevices well to flush them out. I always was paranoid about using the wrong oil on the ring drive due to the warning in the manual- but the last time I serviced I used phil's tenacious oil, and it seems to work fine. Probably not a bad idea to check that the bearings(sealed cartridge IIRC) are spinning smoothly while you're in there- I once had to free up the inner drive side bearing on my hub. Good luck!
im pretty darn sure its not the hub- and for some reason it did not have the problems yesterday. anyway, the hub is very new and the grease/lube in there was fresh looking and i just added a few small dabs of ring drive lube just in case it got a bit worn out.
i also dont think its a chainline thing because it worked fine before and im using almost the exact same chain type i had been using for 2 year (i ran 2 991 and now i went to a 971 cause it was free).
my only guess is that its some issue with chain meshing with worn chainrings/cassette (as ive never seen it happen this way) and causing undue friction. however, the cassette and even middle ring (where it was giving me the worst issues) look worn but not beyond the point of use. it shifts fine and stays in gear, even with my new chain. any suggestions?
....my only guess is that its some issue with chain meshing with worn chainrings/cassette (as ive never seen it happen this way) and causing undue friction. .... any suggestions?
You have to understand that there's a fundamental difference in tooth design between cassettes and chainrings. The cassette is designed around the premise that the RD will guide the chain onto the sprocket, so there's no need to design for a chain to mesh smoothly when feeding from an angle.
Chainrings are different because they have to pick up the chain on the tight side, and have to accept it from a variety of angles. That's why chainring teeth are pointed, and cassette teeth are square.
When you pedal backward, you're asking that the cassette accept and pick up the chain coming from an angle, which it isn't designed to do. The chain plate hits on the edge of the square top of a tooth and with no tension in the upper loop rides up onto the tops of the teeth then seeks to move to a straighter path. The shifting gates built onto the cassette sprockets also contribute to derailing when back pedaling.
Older chains are less prone to the problem because they're nicely broken in and more flexible (sideways). Chains with more bellmouth, or bevel on the inside of the inner plates, are also more forgiving because the bellmouth acts like a funnel making engaging from angles easier.
Autoshifting when back pedaling is common, and those who never experience it are probably those who avoid the more mis-aligned (cross chained) combinations. In any case, it's isn't really a problem because the bike immediately shifts back to the original gear the moment you start pedaling forward. One quick look at any derailleur bike, and it'll be obvious that it was designed for forward pedaling only.
FBinNY-- i totally understand what your saying. i have a pretty good understanding of bicycle workings etc. i understand that bikes are meant to be pedaled forwards, however, one should be able to pedal backwards as well. it does have its uses. "In any case, it's isn't really a problem because the bike immediately shifts back to the original gear the moment you start pedaling forward." seems to be a misguided statement as the the gear clunks back into a gear very clumsily after i start pedaling, and on a hill etc i am liable to break a chain etc. at one point the chain even rode off the smallest cog and was sitting on the cassette lockring- i dont wanna chainsaw through my frame.
anyway, after a LOT of careful observations, i think it is an issue with deformed teeth on the small chainring and potentially the middle one. as i pedal backwards the chain gets stuck on the chainrings but is coming off of the cassette and getting backed up as it reaches the chainrings, causing it to ride up (and sometimes down) the cassette. essentially like chainsuck, how the chain meshes kinda wrong and gets "stuck" in gears ( http://www.fagan.co.za/Bikes/Csuck/ ). i will throw on a new small chainring as that ring is the most deformed. perhaps the adjusted hub/seals had to "seat" as chris king mentioned, but instead of riding for a half hour it took 3 days.
anyway, id love to hear suggestions on how to FIX my problem because as of now it has stumped 2 full-time bike mechanics (me being one of them) and a bunch of knowledgeable enthusiasts.
Is the chain's sticking and releasing on the chainring (what would be chainsuck if you were pedaling forward) enough to cause the upper loop to sag, and then bounce back up as it releases?
If so, you're right to suspect the rings, but also double check, if you haven't already, that the cassette is freewheeling smoothly with bear zero resistance. Also check for any source of drag in the RD pulleys.
Consider that you cannot push a chain, you can only pull it. Pedaling forward, resistance isn't a factor because the chainring pulls the upper loop, which pulls the cassette around then pulls the chain through RD pulleys. Backward, the lower loop is doing the pulling but if there's any drag on the cassette or RD pulleys, can pull chain slack out of the RD cage feed it to the chainring, which then pushs the chain into the upper loop faster than the cassette is taking it up.
12-06-10, 11:30 PM
Suggestion: remove one link from the new chain.
the chain kinda gets stuck on the small ring because its worn/deformed and the chain wont release from the rings smoothly. also, there is as little drag as can be on the freehub- its a king so there is a bit (tiny bit) more drag than say a deore hub but i have other king hubs that dont do this.
thanks for the suggestion about lessening the chain length but its perfect, in fact it may almost be a tad short (if thats possible) because going to big big is sketchy (i know, i know, you dont need to get into the big big but in the off chance every ride or so you forget what gear your in its nice to know your r. der. wont 'splode).
im going to overhaul the bb too, just in case there is undue drag in there, but its a 4 month old chris king bb which has been overhauled once already- they last forever.
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