Common "thunk" in drive

Maybe someone could please point me in the right technical direction as I just don't see anything
upon inspection and I've lost trust in my bike shop technican's expertise (long story). When
pedaling uphill where the bike has the most load on the gears, chain, etc., I feel a clunk
throughout the drive. Problem happens frequently but not readily repeatable. I'm sure this is a
common problem and my question to this posting is primarily most common sources that people have
seen. Any inputs would be greatly appreciated. Thanks.

 

In article <[email protected]>, [email protected] (Cycloneme) wrote:

> Maybe someone could please point me in the right technical direction as I just don't see anything
> upon inspection and I've lost trust in my bike shop technican's expertise (long story). When
> pedaling uphill where the bike has the most load on the gears, chain, etc., I feel a clunk
> throughout the drive. Problem happens frequently but not readily repeatable. I'm sure this is a
> common problem and my question to this posting is primarily most common sources that people have
> seen. Any inputs would be greatly appreciated. Thanks.

First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?

--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

 

I'll have to check. I tends to happen in multiple gears. I thought that the derailer was not setup
properly but I don't really see a problem there. Thanks for your input.

 

"Ryan Cousineau" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, [email protected] (Cycloneme) wrote:
>
> > Maybe someone could please point me in the right technical direction as
I
> > just don't see anything upon inspection and I've lost trust in my bike shop technican's
> > expertise (long story). When pedaling uphill where the bike
has
> > the most load on the gears, chain, etc., I feel a clunk throughout the
drive.
> > Problem happens frequently but not readily repeatable. I'm sure this is
a
> > common problem and my question to this posting is primarily most common sources that people have
> > seen. Any inputs would be greatly appreciated. Thanks.
>
> First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
> one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
>
> --
> Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

Check each link in the chain to ensure that one or more of them isn't seized. It's one of those
litle things that will be missed except under hard pedaling such as up a hill.

 

skipping chain could also be caused by a twisted ring tooth or a tight link.

--
______________________________________

"It's never too late to have a happy childhood."
______________________________________
"Ryan Cousineau" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, [email protected] (Cycloneme) wrote:
>
> > Maybe someone could please point me in the right technical direction as
I
> > just don't see anything upon inspection and I've lost trust in my bike shop technican's
> > expertise (long story). When pedaling uphill where the bike
has
> > the most load on the gears, chain, etc., I feel a clunk throughout the
drive.
> > Problem happens frequently but not readily repeatable. I'm sure this is
a
> > common problem and my question to this posting is primarily most common sources that people have
> > seen. Any inputs would be greatly appreciated. Thanks.
>
> First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
> one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
>
> --
> Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

---
Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.456 / Virus Database: 256 - Release Date: 2/18/2003

 

"Cycloneme" <[email protected]> wrote in message news:[email protected]...
> Maybe someone could please point me in the right technical direction as I
just
> don't see anything upon inspection and I've lost trust in my bike shop technican's expertise (long
> story). When pedaling uphill where the bike
has
> the most load on the gears, chain, etc., I feel a clunk throughout the
drive.
> Problem happens frequently but not readily repeatable. I'm sure this is a common problem and my
> question to this posting is primarily most common
sources
> that people have seen. Any inputs would be greatly appreciated. Thanks.

Couldn't this be a bad bb bearing or hub bearing? I had a thunk in my bb and replaced the sealed
bearing that was shot and it works great.

Bob

 

Sounds more like a chain problem, check the links to see if one of them is seized. Work backwards
from there.

"Bob" <[email protected]> wrote in message news:[email protected]...
>
> "Cycloneme" <[email protected]> wrote in message
> news:[email protected]...
> > Maybe someone could please point me in the right technical direction as
I
> just
> > don't see anything upon inspection and I've lost trust in my bike shop technican's expertise
> > (long story). When pedaling uphill where the bike
> has
> > the most load on the gears, chain, etc., I feel a clunk throughout the
> drive.
> > Problem happens frequently but not readily repeatable. I'm sure this is
a
> > common problem and my question to this posting is primarily most common
> sources
> > that people have seen. Any inputs would be greatly appreciated. Thanks.
>
> Couldn't this be a bad bb bearing or hub bearing? I had a thunk in my bb and replaced the sealed
> bearing that was shot and it works great.
>
> Bob

 

Ryan Cousineau <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, [email protected] (Cycloneme) wrote:
>
> > Maybe someone could please point me in the right technical direction as
I
> > just don't see anything upon inspection and I've lost trust in my bike shop technican's
> > expertise (long story). When pedaling uphill where the bike
has
> > the most load on the gears, chain, etc., I feel a clunk throughout the
drive.
> > Problem happens frequently but not readily repeatable. I'm sure this is
a
> > common problem and my question to this posting is primarily most common sources that people have
> > seen. Any inputs would be greatly appreciated. Thanks.
>
> First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
> one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?

Loose crank arms?

Shaun aRe - heh.....

 

"Shaun Rimmer" <[email protected]> wrote in message
news:[email protected]...
>
> Ryan Cousineau <[email protected]> wrote in message
> news:[email protected]...
> > In article <[email protected]>, [email protected] (Cycloneme) wrote:
> >
> > > Maybe someone could please point me in the right technical direction
as
> I
> > > just don't see anything upon inspection and I've lost trust in my bike shop technican's
> > > expertise (long story). When pedaling uphill where the
bike
> has
> > > the most load on the gears, chain, etc., I feel a clunk throughout the
> drive.
> > > Problem happens frequently but not readily repeatable. I'm sure this
is
> a
> > > common problem and my question to this posting is primarily most
common
> > > sources that people have seen. Any inputs would be greatly appreciated.
Thanks.
> >
> > First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in
> > just one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
>
> Loose crank arms?
>
> Shaun aRe - heh.....
>

I'm with you Shaun. Check the bb and crank arms....

Bob