Conference noted::bicycle

     My guess is that it is the freewheel. This is common particularly
    if you've gone through a few chains with the same freewheel. 
    
     I don't quite get the "longer chain" remark. You should always use the
    same number of links unless you're doing something radical to the gear-
    ing. This could be a part of the problem (if you've gone with more than
    the original number of links on the chain replaced).
    
     Good Luck,
    
               Chip  

Oh shucks I wanted to answer this one!

Had the same problem when I changed chains after about 2000 miles. I had
skipping in only the smallest gear. I even took it back to the bike shop 
and demonstrated the skip to them. They (who were the ones that put it on) 
couldn't tell me what it was. To make a long story short the freewheel 
had worn teeth on the smallest (and most often used) gear. I compared the
cassette with another one I had and noticed their was something of a belly
between teeth. I got a new one and no skip!

commentay/whining follows


I was really steamed at the bike shop however and have not had anymore dealings
with them. I'm in field service and would never (honestly) walk away from
a demonstrably broke system but these guys did. Especially when it was so 
obvious (in the final analysis) what the problem was they really didn't know 
what the problem was. I've had lots and lots of times when I didn't have an
answer and figured out by troublesooting. Thats what I expect. 

Sorry for the commentary,

Fred Mudgett

Since you said it skips in the highest gear under power that makes it sound
like the rear derailleur's "h" adjustment is out...

Since you said the new chain is longer than the old chain that makes it sound 
like a loose or or too long chain.  It should skip other gears here.

Do the easiest first, fiddle with the rear derailleur...

    
    RE: .-1
    
    Your commentary sounds valid to me.  Chain-skip because of worn
    cogs (and a new chain) is a well-known phenomenon.  If the bike
    store installs the chain, then they should at least let you ride
    the bike around the lot or down the block (or up a hill - get
    some pressure on the drive train) to check it out.  
    
    They should also have replacement cogs.  My first experience 
    with this was with Lincoln Guide Service.  They experimented 
    and changed out just the cogs that needed changing, for $2/cog,
    including labor and everything.
    
    Nowadays even most Big Time bike shops don't have a cog-board,
    it seems, much less cogs for the type of freewheel you have (the
    type *they* probably sold you).  Result: I have a lot of perfectly
    good freewheel bodies lying around with worn cogs.  It's the
    typical American throw-away mentality, I guess.
    
    -john

Most common chain skip is a stiff chain link. This doesn't seem to be your
problem because a stiff link will skip on any cog though it does show up on the 
smallest cog (highest gear) the most. A stiff link will cause the chain to skip
about every 2 and a half pedal rev's. To see which link is the culprit stand
next to your bike and back pedal your bike by hand while watching the chain go
through the rear derailleur. As the chain exits derailleur it will stay
kinked. A quick fix is to put a cloth over the chain and bend the chain side to
side. If this doesn't work use a chain tool and push the chain pin on the stiff
link back and forth. Keeping a chain clean and oiled will make them last.

Tom

    If your smallest cog is wearing out first, that's a pretty rare thing!
    One of the following is likely:
    
    o Your derailleur adjustment is wrong.
    
    o You're riding LOTS of TTs FAST, using "Lemond" gearing.
    
    o Your shifting habits are bad.
    
    Generally, you shouldn't be in your smallest cog long enough to wear
    it out, even though (since it's the smallest) it's most prone to
    wear.  When you're in the big ring, you have to be going supersonic
    speeds to justify being in that gear; when you're on the small ring,
    you should never use the smallest cog at all.
    
    
    MATT

    What is "your highest gear ratio"? - if you mean your smallest cog,
    regardless of chainring, then the next question is: do you ever use the
    small chainring with the smallest rear cog? If the answer is yes, you
    could have worn the cog quite easily.
    
    Another thing which can happen is you have a rivet or two which
    protrude too far from the plates of the chain and they catch on the
    next cog up.
    
    If you've got a lot of miles on the freewheel, you could have bent or
    weak springs on the pawls, contributing to skip -- but it wouldn't
    matter what gear you were in, most likely.

    Thanks for all the suggestions.  This over night service is really
    good!
    
    I did say highest gear ratio, didn't I?  Oops.  I meant the lowest
    gear.  42 chainwheel and 19 cog.  The only excuse is that it was rather
    late at night when I typed the base note in.
    
    I'll take the bike out at lunch and do some experiments and see (a) if
    I can make it happen with more than one cog, (b) does it happen every
    2.5 revs or so and (c) can I force it to happen by free wheeling and
    then jamming hard (not destructively so, though).
    
    re .1  My fault, I didn't explain what I meant by the 'longer' chain. 
    Both chains have the same number of links.  It seems that the
    individual links of Shimano chains are longer than Sedis ones.  It's a
    minute difference, but the owner of the bike shop I use the most
    reckons that it's enough to make a difference in shifting.  He
    demonstrated the difference to me by suspending one chain of each type
    from the same point.  These were new chains just out of the box and
    with the same number of links.  The Shimano chain was about 3 to 4 mm
    longer.  I don't think he's trying to bs me.  He stocks the full range
    of Shimano, Sedis and other chains.  We are also on first name terms,
    and he remembers my name every time.
    
    Re .4 Quentin, for that is his name, also has a well stocked cog board
    and has been helpful in the past in getting stuff that he doesn't
    stock.
    
    Richard

I, last week, changed out the chain on my Trek 1400.  I did not look to see
what kind of chain the factory had put on it but I changed it to a Sedis.
After changing the chain, I took it for a test spin and it was making noise
in the three smallest casette cogs and would not index properly.  I adjusted
the barrel adjuster (cable tension) and it fixed the problem.  I've got about
150 miles on the new chain and it works fine.

Mark

I switched to a new chain earlier this spring (no real reason, I just thought
it was time and I was doing some other fixes).  The new chain whould skip badly
in the middle cogs, mostly the 17.  It was a narrow 600 Ultegra, just like the
one it replaced.  Since the middle cogs are used the most they could have been
worn, but it did it on two sets of cogs.  I then switched wheels with someone
else and my wheel didn't skip on his bike but his wheel skipped on mine.  The
conclusion is the chain was the problem.  I switched to a sedisport and it's
OK.

    I did some experiments at lunch time yesterday.  First I made sure that
    the set up of the derailleur is spot on.  I had to loosen off the L
    setting by half a turn, so that may have helped a bit.  I also adjusted
    the B? setting, the one which controls how close the jockey wheel is
    the the cluster.  I moved it much closer.  I had forgotten to change
    the setting from when I had a 24 tooth cog on for mountain climbing
    (well - a hilly century, anyway).  I also made sure that the indexing
    setting was spot on.  Now for the road test.
    
    I have a few nice hills near home which I tried climbing using the 42
    tooth chainwheel and the 19, 18 and 17 tooth cluster cogs.  I did not
    try the other cogs - too hard.  I could not make the 18 or 17 cogs slip
    at all, even standing out of the saddle and pushing/pulling with both
    legs as hard as possible.  I got the 19 cog to slip twice.  That's in
    about 20 minutes of testing.  It was completely irregular and
    unpredictable.  There are no stiff links and the freewheel seems to be
    OK.  It could be the cog.  I'll try a different 19 cog and see what
    happens.
    
    One other solution could be that when I am really pushing hard, frame
    flex might allow the chain to mis align with the cog.  Could this
    happen?  It's a fairly stiff, tight Reynolds 531 frame and I haven't
    had this problem before.  Maybe I'm getting stronger :-)
    
    Richard.

    I put a new 19 cog on on Saturday and tried to get it to skip.  No
    skips.  Looks like it was the cog.
    
    Thanks for all the input.
    
    Richard.

I have a new (< 20 miles) bicycle with 3x7 gearing as follows:

   *  32, 42, and 52 chainrings
   *  27-13 (roughly) freewheel cogs

I am having some problems with the three tallest ratios (i.e. the 52 chainring 
and the three smallest freewheel cogs).  First, the chain is noisy in these 
positions.  I expected to be able to quiet it with some fine adjustment of the 
front shifter but I couldn't.  Second, when I am standing on the pedals, I can 
easily cause the chain to jump a tooth.

The rear shifer is indexed (Suntour, I think).  Of course, the bike store may
not have aligned it perfecly.

Most of the replies here are concerned with worn cogs.  As I said earlier, the 
bicycle is new (and the cogs looked unused when I took delivery).

Maybe the rear derailleur is out of adjustment laterally; maybe it isn't close
enough to the cogs.  Maybe the chain is too long?  What is a good plan of 
attack here?

Any advice appreciated.
Erik
       

    One of the things that you mentioned, "the derailleur too far
    from the chain", can certainly cause that problem in high
    gears/cogs.  I don't know about the low ones; someone else
    will have to help on that one.
    
    I can't believe the shop would have let it out the door in such
    a poor state of adjustment, though.
    
    Good Luck,
    
    r�

    Well, if it's a new bike, and/or there's any noticeable "droop" in the
    chain in one or more gears, the probable cause is that the chain is
    just too long.  Try removing a link (actually 2) and see if it's any
    better.  If it's an older installation where things used to be ok,
    then the fix is to bite the bullet and get both a new chain and
    freewheel.  Murphy's law: a new chain will skip with an old freewheel,
    and a new freewheel will skip with an old stretched chain...

    How about just taking it back to where you got it and have
    them readjust it?  It sounds like just an adjustment problem.
    
    good luck.

    I have Suntour on my (now almost new) MTB, and I went through a long
    period of trying to adjust it as it broke in.  I suffered from skipping
    gears, popping out of them, etc.  You might try adjusting it.  Now that
    I have it dialed in, it works fine.  Try note 1993.19 for some info on
    how to adjust indexed shifting.  I had to play with it a while, but I
    finally got it right.  And it was a lot faster for me to do it, then
    run back and forth to the shop
    
    /bob

    Thanks for the help.  I will try the sequence described in 1993.19
    as soon as I can.
    
    As to why I want to do this myself, I consider time spent learning
    how to work on the bike preferable to time spent traveling to and 
    from the bike store (~25 miles each way) and waiting for them to
    work on it.
    
    Erik

    I aligned my rear derailleur last night using the process described
    above.  After a short time, the chain noise disappeared.
    
    I stood up a bit on my ride in this morning and no chain skip.
    
    Erik