Bicycle Mechanics - Is there a bicycle mechanic in the house!?

My bike has a mysterious, intermittent ailment. It’s a 2003 61cm 27-speed Lemond Tourmalet with nearly 12,000 road miles, originally equipped with Shimano Tiagra and 105 components. It has developed some kind of drive train problem that causes the crank arms and pedals to sometimes skip or slip repeatedly, not just when standing on the pedals, but even when subjected to only moderate pedaling pressure. Sometimes I can ride for weeks and hundreds of miles without a problem, and then suddenly it starts slipping so badly that I have to walk it up a hill. The problem goes away before I can get to a bike shop and demonstrate the problem to a mechanic. It happened again yesterday during my commute home from work. After taking the rear wheel off and carefully checking unsuccessfully for the source of the problem, I thought to myself that I would baby the bike the rest of the way home so as to be certain that the problem was still in effect when I reached home and could then take the bike to the bike shop in the back of my car and demo the problem at the bike shop, once and for all. By the time I mostly coasted down the other side of the hill, the problem had vanished again!

When the problem occurs, changing to a different chain ring in the front (I have a triple) or different cluster gear in the back, has no effect. When the skipping or slipping occurs, the only thing I can see as I look down at the drive train is that the lower wheel of the rear derailleur flicks slightly forward each time the pedals skip or jump, but not to one side or the other as if the chain were trying to switch to a lower or higher gear on the cluster. I do not notice any behavior changes with the chain or the gears. There is also no shifting noise associated with this slippage and no visible sign of the chain attempting to climb up to the next larger gear as there is when the chain is on the verge of switch gears. The only noise is the sound of the chain seemingly slipping or jumping teeth and then catching; however, I am unable to visually verify that the chain is actually slipping.

The chain on my bike seemed to begin slipping teeth 6 months ago or so when I would put all my weight on the pedals when standing to climb or accelerate. Then the problem gradually began to sometimes happen even when just pedaling while seated. Obviously, this was both scary and dangerous, nearly causing me to crash several times. I’ve taken the bike into the bike shop several times for quick, non-appointment diagnoses. (the waiting list for an official service appointment is too long) Originally, the diagnosis was that the drive train components on my bike were old and worn out and needed replacing. This is where the story gets really weird. So, I saved my money and between Christmas and New Years, I upgraded and inve$ted in Shimano Ultegra replacement parts for the large and middle chain ring (they were out of stock on the small chain ring) and replacement 9-speed gear cluster. At the recommendation of the bike shop sales person, I bought a 9-speed non-Ultegra replacement master link chain that he used and was touted as being better than Ultegra. I installed all these myself, being very careful to follow the installation instructions. At first, I thought the replacement parts had solved the problem….until the skipping started reoccurring!

It appears to me that the teeth on the chain rings and cluster are straight and I’ve checked for stiff links in the new chain or a problem with the master link. The bottom bracket was replaced by the bike shop sometime last summer. I’ve replaced the shifting cables in the past year due to breakages.The rear derailleur appears to be working properly.

I’m scheduled for a double century in a week and a half. Anybody got any ideas on what kind of gremlin is in my bike and how I exorcise it?

If your drive train has been replaced, and you are not having unintended gear shifts, the only other thing I can think of is that your ratchet in the hub could be failing. I have blown one up on my mountain bike.

You could try sacrificing a live chicken and eating some frogs eyes.

Hello:
install a New cassette and chain and be SURE to lube all pivot points on your derailuers and chain.
and do bouble check on your chainrings, if they look like they are becomming worn do replace them.
and also do lubricate all cables and housing.

Thank
You
Earl
Bicycle mechanic for over 30 yrs.

Did you know a chain wears out? The cassette wears at the same rate. Take it to the PBS and have the chain and cassette replaced. At 12K miles, maybe the chainrings too.

He said he replaced the cassette, chainrings and chain.

Could the derailleur jockey wheel be striking the cassette teeth as with a misadjusted B screw?

The skipping has returned like it was before the parts swap?
It really seems like an adjustment issue.
However, things like a cable kinked right at the point it goes into the housing or a bike dropped on the der and gouging it right at the pivot can cause problems in one or two gears.
be sure to check your cable at the stop(In the shifter) to make sure it is not fraying, that can cause some minor issues, until it finally breaks and leaves you in the twelve.

The problem is in the freehub mechanism; the ratchet pawls are not locking properly.

Good news is that the part is replaceable. Bad news is that it's not cheap, just a little less than a new hub.

You can remove it yourself with a 10mm hex wrench...or just let the LBS do the work.

Good luck.

A freehub for Shimano will run $24ish for Tiagra and $35ish for 105 (at a bike shop). Likely your hubs are not Shimano, so that makes it harder to figure, maybe Ritchey? They run around $25 or so. And some of the non Shimano hubs use something other than a 10mm allen to remove them.

I had this happen with a new drivetrain but used wheels and swapped the freehub and all was fixed

If your drive train has been replaced, and you are not having unintended gear shifts, the only other thing I can think of is that your ratchet in the hub could be failing. I have blown one up on my mountain bike.

You could try sacrificing a live chicken and eating some frogs eyes.

I agree and can help you with the frogs eyes.

When I read this:

"When the skipping or slipping occurs, the only thing I can see as I look down at the drive train is that the lower wheel of the rear derailleur flicks slightly forward each time the pedals skip...."

and also this:

"At the recommendation of the bike shop sales person, I bought a 9-speed non-Ultegra replacement master link chain that he used and was touted as being better than Ultegra."

...my suspicion is BAD CHAIN. Can you give more information about what brand of chain you are now using? The forward flicking condition of the rear derailleur sounds like a stiff link or incompatible master link to me. Since you already have the master link, I would say you should remove the chain then flex each link in a tight radius while raising and lowering both ends of the chain in your hands. The links should be fluid, and able to effortlessly conform to a tight radius. Stubborn stiff links will reveal themselves right away. A chain with these hidden gremlins will make a drivetrain behave the way you're describing.

A high priced, highly touted chain is not immune to manufacturing defects, in fact, if the un-named, highly regarded chain happens to be a Wipperman - I'd recommend you take it off and install the Ultegra you speak of immediately and see if that cures the condition. I had a Wipperman 9x1 stainless 9 speed chain on my Dura Ace/Ultegra 9 speed bike and it behaved just as you describe. When I cleaned it out with mineral spirits and used compressed air to dry, then re-lubed, it only got worse. It was clearly defective. I sent it to Wipperman's US distributor Velpex Marketing for their inspection and within a week they mailed me a new one. I now have an IRD on there which is much quieter and more flexible. I actually like the stiffness of the Wipperman and don't mind the increased noise, but when a chain is so stiff that it can't hug a cog with fluidity, your drivetrain becomes a nightmare :(

Now, after saying all that - I will give my best theory #2 and say you've got a failing cassette body. But my primary bet is on CHAIN.

When I read this:

"When the skipping or slipping occurs, the only thing I can see as I look down at the drive train is that the lower wheel of the rear derailleur flicks slightly forward each time the pedals skip...."

and also this:

"At the recommendation of the bike shop sales person, I bought a 9-speed non-Ultegra replacement master link chain that he used and was touted as being better than Ultegra."

...my suspicion is BAD CHAIN. Can you give more information about what brand of chain you are now using? The forward flicking condition of the rear derailleur sounds like a stiff link or incompatible master link to me. Since you already have the master link, I would say you should remove the chain then flex each link in a tight radius while raising and lowering both ends of the chain in your hands. The links should be fluid, and able to effortlessly conform to a tight radius. Stubborn stiff links will reveal themselves right away. A chain with these hidden gremlins will make a drivetrain behave the way you're describing.

A high priced, highly touted chain is not immune to manufacturing defects, in fact, if the un-named, highly regarded chain happens to be a Wipperman - I'd recommend you take it off and install the Ultegra you speak of immediately and see if that cures the condition. I had a Wipperman 9x1 stainless 9 speed chain on my Dura Ace/Ultegra 9 speed bike and it behaved just as you describe. When I cleaned it out with mineral spirits and used compressed air to dry, then re-lubed, it only got worse. It was clearly defective. I sent it to Wipperman's US distributor Velpex Marketing for their inspection and within a week they mailed me a new one. I now have an IRD on there which is much quieter and more flexible. I actually like the stiffness of the Wipperman and don't mind the increased noise, but when a chain is so stiff that it can't hug a cog with fluidity, your drivetrain becomes a nightmare :(

Now, after saying all that - I will give my best theory #2 and say you've got a failing cassette body. But my primary bet is on CHAIN.

If I was a betting man, I'd say the replacement chain was a SRAM one , and the problem was certainly the pawls (siezed/worn) failing to engage in the freehub. You can replace the freehub, or try stripping it off the hub (10mm allen key), bathing it in degreaser, then oiling it, and see how you go - net cost around $5 for allen key and consumables.

Or someone installed a Wipperman upside down. http://www.thesmilies.com/smilies/innocent0009.gif

I agree about the wheels being a problem. If it doesn't check the hangar(if you haven't already) then check frame alignment. I think everyone exhausted ideas for this one.

I want to belatedly thank Avalanche325, Nessism, Rev.Chuck, and Neccros for their correct diagnosis that the problem was a failing clutch in the hub. I acted on their advice and replaced the old wheel with a new one (Ultegra hub with Mavic OpenPro rim) and the problem went away! Hallelujah!

If your drive train has been replaced, and you are not having unintended gear shifts, the only other thing I can think of is that your ratchet in the hub could be failing. I have blown one up on my mountain bike.

That's what I think too. From your description my guess is that you need to have your freehub body replaced. That's about a $50.00 job for parts and labor.

That's what I think too. From your description my guess is that you need to have your freehub body replaced. That's about a $50.00 job for parts and labor.

That was my first thought (I don't recall ever reading this thread). But was it not worth it to do this though? Even if you do get someone else to do it, $50 for a functional wheel is a deal.