Bicycle Mechanics - :specialized: chain skip issues :help:

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endeverleverone
12-03-05, 06:17 PM
so i bought this specialized hardrock sport moutain dealie bike , and ive had this bike for less than 2 months and im having trouble when i put allot of force into my ride , the chain skips randomly , it feels like trying to switch to another gear and just trips back and disrupts my ride , happens the most when i have to slowdown/speed up rapidly , i took the bike in for my first free tune up and they just slightly adjusted most of the other slight technicall problems i gave the bike from my "mishaps" but the chain skip left this guy clueless, he tried to make as much adjustments as he could but i got no lastting result , i left the bike shop feeling like my bike is just weak. quite sad. some one suggested maybe making my chain a link shorter, and i wonder if that could do the trick or cause more problems in the long run.
please adress my dilemma.

my first post yay!


HillRider
12-03-05, 07:58 PM
Any idea where (front at the crank or rear at the cassette) the skiping is occuring?

It sounds like a derailleur alignment problem. If it's in front the derailleur may be mis-aligned or the stops not set properly. In the rear either the derailleur hanger isn't aligned properly or the shift cable needs to be adjusted.

endeverleverone
12-03-05, 09:02 PM
definately the rear cassette , i btw only like riding on the smallest rear and largest crank setting to get the most out of the bike (and my legs) funny you mention the derailer , cus ive had the inconvenience of wearing pants and riding to fast and the derailer took a bite out of my pantleg and got completely contorted in the process , rendereing the bike pretty useless until i gave it a therapy session with the curved end of a hammer , i managed to readjust the derrailer so it wouldnt get any contact with the chain and become ridable , swithchin gears on the crank was another story until i took it to the bike shop , he checked it out and the derailer is as aligned as itll get , yet we all believe there is a mysterious problem with the cassette , all these parts are as seemingly new as can be , except for once i crashed and misaligned the piece with 2 smaller gears that are apart of the mechanism that shifts the back gears (dont know what its called) and had that aligned as much as it could , as well as that one time i hopped a gap and landed on a corner with my rear tire bending the rim a bit and completely flattening my tire , yet i got my spokes adjusted as to not get any contact with the brake shoes ..... those are the only incidents that have altered the newness of my bike . i left the bikeshop feeling maybe i bought a bike that isnt as strong as it looks, i am indeed looking for that perfect bike for what i consider "agressive multi terrain commuting"


Siu Blue Wind
12-03-05, 09:25 PM
I can't believe you beat the heck out of your two month old bike. And I can't believe you took a hammer to it. And I can't believe your mechanic is clueless. Did you tell him of your "mishaps?" Wow. Where is the LOVE, man??!??

endeverleverone
12-03-05, 09:41 PM
it was tough love in my opinion , i didnt hurt the bike with the hammer ... i just pried the derailer and readjusted the position of it back to a ridable one that doesnt contact the chain , the derailers fine at this point , i find this chain problem pretty tricky and there isnt much logic to explain why its a persistent issue , it doesnt happen when i ride smoothly , its when i get all high tech in and out of traffic . i hope i can find some resolution , other than gettin a faster stronger bike. i described in detail all my mishaps to the mechanic , and he did make a difference to the other slight misalignments to the bike , its just that damn chain skipping.


please help me all knowing internet! please oh please!

Siu Blue Wind
12-03-05, 10:03 PM
When you pried the derailleur what did you use as a leverage, the cassette?

gm1230126
12-03-05, 10:05 PM
Could even be a tight link in the chain. Two months of hard riding some in weather with no lube can do that. A word of advice.... learn to ride and land right before taking off.

endeverleverone
12-03-05, 10:20 PM
siu blue wind::::::: i used the disk where the pedals are as leverage ,


gm120126:::::::::: my weather is hot and subtropical(miami) except for our temporary excuse for a winter (chilly nights and cold days 3 days a week)
some thing wrong with the chain certainly seems plausible ... thanks

what do you mean by "land right"?

mechBgon
12-03-05, 10:23 PM
all these parts are as seemingly new as can be , except for once i crashed and misaligned the piece with 2 smaller gears that are apart of the mechanism that shifts the back gears (dont know what its called) and had that aligned as much as it could

Just doing a high-level skim, it looks like it's the front derailleur that got the hammer action, and he's bent his rear derailleur and/or rear-derailleur hanger with a crash. Which means HillRider is on target with the place to start: the RD hanger should be aligned and then the RD replaced if necessary. And they should also look for stiff links in the process.

endeverleverone
12-03-05, 10:31 PM
thats pretty much on point mechbgon - ive had the rear derailleur& rd hanger aligned and doesnt have any real damage at this point , a thourogh analysis of my chain is the next step here . and mebbe some lube.


much thanks

mechBgon
12-03-05, 11:49 PM
You don't really "align" a derailleur. If you twisted up something with that many pivots in it, it may be time to plunk down another $20 and get a fresh one if you can't get it to work properly.

Here's a quick tip to start with, on the chain aspect. If the chain has one damaged point in it, then it will show up about once every 2 1/2 revolutions of the cranks when you're powering hard, because that's how long the chain takes to "make a lap" of the drivetrain. The damaged part could be a kinked link that doesn't want to pivot freely, or a twisted section. If you lean the bike against a wall and sight down the chain from the rear as you backpedal the cranks by hand, you will probably see the twisted part coming along, if there is one. If the chain "hop-hops" as it goes through the rear sprocket and the rear derailleur (the deal with the two rollers), then try pivoting those hopping links by hand and see if they're not moving freely.

unkchunk
12-04-05, 12:14 AM
endeverleverone, how much do you weigh?

endeverleverone
12-04-05, 12:17 AM
i weigh a clean 200 lbs

unkchunk
12-04-05, 12:33 AM
Maybe you have ghost shifting. In short, you're heavy enought to generate alot of force that flexes your bike's frame with a high torque pedal push. The cables don't flex with the frame so the difference causes the rear derailer to shift. If the random shifting only happens with really hard pedaling, that's what might be happening. Under the bottom bracket there is a plastic guide for the derailer cable and some oil there might help aliviate the problem a little.

endeverleverone
12-04-05, 12:58 AM
ghost shifting ey?? interesting , you kno - i have foot traps and road tires , so i can put that extra "umph" maybe that affects the force distribution as well.........damn physics!

Retro Grouch
12-04-05, 07:47 AM
A bicycle is a simple machine. Whenever it doesn't seem to respond to normal tuneing imputs the thing to do is to return everything to the default as-new condition.

In your case, the first thing to check is the alignment of the rear derailleur hanger. In my experience that's almost always the problem.

Uh - don't beat your bike with a hammer anymore. Whatever problems you're having it's not the bike's fault.

endeverleverone
12-04-05, 12:30 PM
why does everyone think i beat the bike with the hammer out of anger??? the derailleur was twisted INTO the chain and wouldnt even pedal. so i bent it back...

so the things to inspect are the rear derailleur hanger and any chain imperfections.

i am not an angry person with a hammer. thanks

endeverleverone
12-07-05, 03:26 PM
after a quick consultation , with my lbs(figuring out acronyms is fun) and coming to an education that the problem at hand is not so much the rd(!) arm but actually a few teeth in the bottom cog of the casstete come much to close to the chain and hard force from pedaling causes is to jump to the next cog until the aligned teeth catch again.

diagnosis - ironically this mechanic(from a different bike shop) honestly suggested using a flat head HAMMER to set the teeth back a millemeter further from the chain.

maybe its a miami thing. hammers solve ALL of natures problems ive come to realize. if it doesnt work he offered me a GREAT price on a duro ace shiny new titatium cassette. either way things lloook very good .

hammer hammer hammer !