A problem with gears.

Discussion in 'UK and Europe' started by Donny, Dec 8, 2004.

  1. Clive George

    Clive George Guest

    "Martin Wilson" <[email protected]> wrote in message
    news:[email protected]
    > On Mon, 13 Dec 2004 06:38:35 +0900, James Annan
    > <[email protected]> wrote:
    >
    > >Pete Biggs wrote:
    > >
    > >>> It is, in my opinion, undoubtedly dirt which is the main factor in
    > >>>bicycle chain wear.
    > >>
    > >>
    > >> I'm not totally convinced it's the main factor. Might be, but the

    issue
    > >> seems far from clear to me as there are so many factors.

    > >
    > >You've just had it demonstrated to you why dirt must the main factor:
    > >compare the stress of a loaded tandem riding big hills in clean dry
    > >roads, to an MTB in muddy areas.
    > >
    > >James

    >
    > Take a look at the clydesdale forum over on mtbr.com and you'll find
    > riders who have destroyed their gearing in one day because of the
    > torque they have put into their gearing. There's also reports of
    > excessive chain wear over normal weight riders. I can't believe anyone
    > would be surprised by this. Personally I think your not firing on all
    > cyclinders if you think load isn't a factor with regard chain and
    > cassette wear even if its not the main factor but hopefully if you
    > read some real world experiences you might think differently.


    How about having some real world experience, not just reading it? Remember,
    James is talking about tandems, which means twice the force.

    Then check out the results for tandem riders giving clean chains a very hard
    time - there are people out there who are doing so and not getting
    significant wear.

    Now destroying gearing is a different matter - folding cassettes (we won't
    use the shimano ones with the spider any more - they're not strong enough)
    and stripping freewheels (shimano free hubs aren't strong enough for MTB
    tandem use) are typical modes of failure - and have both happened to us. But
    that's breaking things, not wearing them out.

    cheers,
    clive
     


  2. Simon Brooke

    Simon Brooke Guest

    in message <[email protected]>, Martin Wilson
    ('[email protected]') wrote:
    > On Mon, 13 Dec 2004 06:38:35 +0900, James Annan
    > <[email protected]> wrote:
    >
    > >Pete Biggs wrote:

    >
    >>> I'm not totally convinced it's the main factor.  Might be, but the
    >>> issue seems far from clear to me as there are so many factors.

    >>
    >>You've just had it demonstrated to you why dirt must the main factor:
    >>compare the stress of a loaded tandem riding big hills in clean dry
    >>roads, to an MTB in muddy areas.

    >
    > Take a look at the clydesdale forum over on mtbr.com and you'll find
    > riders who have destroyed their gearing in one day because of the
    > torque they have put into their gearing. There's also reports of
    > excessive chain wear over normal weight riders. I can't believe anyone
    > would be surprised by this. Personally I think your not firing on all
    > cyclinders if you think load isn't a factor with regard chain and
    > cassette wear even if its not the main factor but hopefully if you
    > read some real world experiences you might think differently.


    Clearly stress on the transmission has to be an issue. However, as
    another datapoint, I have a friend who is a time trialist who weighs
    about sixteen stone and habitually uses 180mm cranks, a 60 tooth
    chainring, and a relatively slow cadence. And wins. The stress he puts
    into his transmission (Campag ten speed) makes me cringe. Yet he
    doesn't complain of transmission wear (he does, unsurprisingly,
    complain about his knees).

    A well maintained, reasonable quality, clean bicycle transmission seems
    to me to last a reasonably long time. Certainly my own mountain bike
    chains wear out much faster than my road bike chains, with similar
    levels of power input and similar maintenance.

    So I still hold to my opinion that dirt is at least _a_ major issue and
    probably _the_ major issue in transmission wear.

    --
    [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
    "This young man has not the faintest idea how socialists think and does
    not begin to understand the mentality of the party he has been elected
    to lead. He is quite simply a liberal"
    -- Ken Coates MEP (Lab) of Tony Blair
     
  3. James Annan

    James Annan Guest

    Martin Wilson wrote:


    >
    > Personally I think your not firing on all
    > cyclinders if you think load isn't a factor with regard chain and
    > cassette wear even if its not the main factor but hopefully if you
    > read some real world experiences you might think differently.


    Personally I think you're not firing on all cyclinders if you prefer to
    make up some feeble straw man rather than just read what I said, which
    was neither ambiguous nor inaccurate.

    James
    --
    If I have seen further than others, it is
    by treading on the toes of giants.
    http://www.ne.jp/asahi/julesandjames/home/
     
  4. Pete Biggs

    Pete Biggs Guest

    James Annan wrote:
    > You've just had it demonstrated to you why dirt must the main factor:
    > compare the stress of a loaded tandem riding big hills in clean dry
    > roads, to an MTB in muddy areas.


    Do the tandems have the same gears as the MTB's, or do they have larger
    cogs? The chain has to rotate more on smaller sprockets, causing more
    wear.

    I don't know how the stresses compare anyway. Serious off-roaders apply
    serious amounts of torque.

    Not convinvced it's mostly down to dirt yet,

    ~PB
     
  5. dkahn400

    dkahn400 Guest

    Pete Biggs wrote:

    > Do the tandems have the same gears as the MTB's, or do they have
    > larger cogs? The chain has to rotate more on smaller sprockets,
    > causing more wear.


    No, the chain rotates more with larger sprockets. Imagine a 30-tooth
    chainring with a 15-tooth sprocket. For each complete rotation of the
    cranks the chain advances 30 links. Now think of a 60-tooth chainring
    with a 30-tooth sprocket. The gearing is the same but the chain is
    advancing at twice the rate - 60 links per crank revolution. The chain
    tension, however, is greater with the smaller chainring and sprocket.
    --
    Dave...
     
  6. Clive George

    Clive George Guest

    "Pete Biggs" <pwrinkledgrape{remove_fruit}@biggs.tc> wrote in message
    news:[email protected]
    > James Annan wrote:
    > > You've just had it demonstrated to you why dirt must the main factor:
    > > compare the stress of a loaded tandem riding big hills in clean dry
    > > roads, to an MTB in muddy areas.

    >
    > Do the tandems have the same gears as the MTB's, or do they have larger
    > cogs? The chain has to rotate more on smaller sprockets, causing more
    > wear.


    Tandems tend to have the same on the back, and bigger high gears on the
    front. Eg we have 11-32/34 and 24/38/50.

    > I don't know how the stresses compare anyway. Serious off-roaders apply
    > serious amounts of torque.


    And not-so-serious off-road tandem teams apply even more serious amounts of
    torque.

    cheers,
    clive
     
  7. Donny

    Donny Guest

    soup wrote:
    >
    > [snippage]
    >
    > 4,000 miles and never a new chain/cassette, is the small cog worn at
    > all
    > (shark finning of the teeth) has the chain stretched? If either of
    > these
    > apply maybe it's time to think of new ones .


    The small cog definitely has some teeth that look more shark-finny than
    the others; I reckon I need to replace it.

    The two smallest cogs on the cassette are separate from the rest so
    hopefully I could just buy replacements for these?

    I guess I'll need a new chain as well?

    Cheers,
    Donny
     
  8. Pete Biggs

    Pete Biggs Guest

    dkahn400 wrote:
    > Pete Biggs wrote:
    >
    >> Do the tandems have the same gears as the MTB's, or do they have
    >> larger cogs? The chain has to rotate more on smaller sprockets,
    >> causing more wear.

    >
    > No, the chain rotates more with larger sprockets. Imagine a 30-tooth
    > chainring with a 15-tooth sprocket. For each complete rotation of the
    > cranks the chain advances 30 links. Now think of a 60-tooth chainring
    > with a 30-tooth sprocket. The gearing is the same but the chain is
    > advancing at twice the rate - 60 links per crank revolution. The chain
    > tension, however, is greater with the smaller chainring and sprocket.


    Chain links rotate more with smaller sprockets as they conform to the
    sprockets. Friction within the chain from this factor is highly
    significant. Tests have proved that larger sprockets are more efficient.

    ~PB
     
  9. Pete Biggs

    Pete Biggs Guest

    Clive George wrote:

    >> Do the tandems have the same gears as the MTB's, or do they have
    >> larger cogs? The chain [links have] to rotate more on smaller

    sprockets,
    >> causing more wear.

    >
    > Tandems tend to have the same on the back, and bigger high gears on
    > the front. Eg we have 11-32/34 and 24/38/50.


    A combination that causes less wear.

    ~PB
    (edit in square brackets)
     
  10. Pete Biggs

    Pete Biggs Guest

    dkahn400 wrote:
    > Pete Biggs wrote:
    >
    >> Do the tandems have the same gears as the MTB's, or do they have
    >> larger cogs? The chain has to rotate more on smaller sprockets,
    >> causing more wear.

    >
    > No, the chain rotates more with larger sprockets. Imagine a 30-tooth
    > chainring with a 15-tooth sprocket. For each complete rotation of the
    > cranks the chain advances 30 links. Now think of a 60-tooth chainring
    > with a 30-tooth sprocket. The gearing is the same but the chain is
    > advancing at twice the rate - 60 links per crank revolution. The chain
    > tension, however, is greater with the smaller chainring and sprocket.


    take two:

    It's not particularly important how many links are contacting the
    sprockets. More relevant is friction within the chain, which in turn
    causes sprocket wear as the chain elongates. Chains wear themselves out
    more rapidly when they are forced to conform to smaller sprockets. I
    believe this factor more than makes up for the difference in number of
    teeth that the chain is contacting.

    Nb. I include chainrings with "sprockets".

    ~PB
     
  11. Clive George

    Clive George Guest

    "Pete Biggs" <pwrinkledgrape{remove_fruit}@biggs.tc> wrote in message
    news:[email protected]
    > Clive George wrote:
    >
    > >> Do the tandems have the same gears as the MTB's, or do they have
    > >> larger cogs? The chain [links have] to rotate more on smaller

    > sprockets,
    > >> causing more wear.

    > >
    > > Tandems tend to have the same on the back, and bigger high gears on
    > > the front. Eg we have 11-32/34 and 24/38/50.

    >
    > A combination that causes less wear.


    Not convinced - both end up using the 11t, which is where the worst rotation
    is.

    cheers,
    clive
     
  12. Pete Biggs

    Pete Biggs Guest

    Clive George wrote:

    >>>> Do the tandems have the same gears as the MTB's, or do they have
    >>>> larger cogs? The chain [links have] to rotate more on smaller
    >>>> sprockets, causing more wear.
    >>>
    >>> Tandems tend to have the same on the back, and bigger high gears on
    >>> the front. Eg we have 11-32/34 and 24/38/50.

    >>
    >> A combination that causes less wear.

    >
    > Not convinced - both end up using the 11t, which is where the worst
    > rotation is.


    Agreed the worst rotation is at the 11t but a smaller chainring causes
    more rotation still, hence more wear.

    ~PB
     
  13. dkahn400

    dkahn400 Guest

    Pete Biggs wrote:

    > Chain links rotate more with smaller sprockets as they conform to
    > the sprockets. Friction within the chain from this factor is
    > highly significant. Tests have proved that larger sprockets are
    > more efficient.


    OIC. You mean the rotation of the link itself as it passes over the
    sprocket. I thought you were referring to rotations of the complete
    chain.

    --
    Dave...
     
  14. Pete Biggs

    Pete Biggs Guest

    dkahn400 wrote:
    > OIC. You mean the rotation of the link itself as it passes over the
    > sprocket. I thought you were referring to rotations of the complete
    > chain.


    That's right, sorry I didn't make it clearer. It's the kind of thing I
    find difficult to put into words, but that doesn't stop me being
    interested in the subject :)

    ~PB
     
  15. James Annan

    James Annan Guest

    Pete Biggs wrote:

    > James Annan wrote:
    >
    >>You've just had it demonstrated to you why dirt must the main factor:
    >>compare the stress of a loaded tandem riding big hills in clean dry
    >>roads, to an MTB in muddy areas.

    >
    >
    > Do the tandems have the same gears as the MTB's, or do they have larger
    > cogs? The chain has to rotate more on smaller sprockets, causing more
    > wear.
    >


    Basically the same, although there is certainly a tendency to smaller
    granny rings for touring and hills. 18T is not unheard-of. We also like
    a large big ring for flat roads, but that is not really relevant to the
    discussion.

    > I don't know how the stresses compare anyway. Serious off-roaders apply
    > serious amounts of torque.
    >


    Actually, most of whon you are considering as "serious off-roaders" are
    probably skinny midgets who exert rather low forces and use unusually
    high gears. A pair of lardy yanks carrying a tent hauling ass up a hill
    in their granny gear, now THAT is a serious amount of torque, even
    though they are going at walking speed!

    > Not convinvced it's mostly down to dirt yet,


    Nevertheless, it is. Obviously load will also have some effect too, but
    it can not explain the order-of-magnitude (and more) differences in wear
    that are routinely found between clean and dirty use.

    James
    --
    If I have seen further than others, it is
    by treading on the toes of giants.
    http://www.ne.jp/asahi/julesandjames/home/
     

  16. >The small cog definitely has some teeth that look more shark-finny than
    >the others; I reckon I need to replace it.
    >
    >The two smallest cogs on the cassette are separate from the rest so
    >hopefully I could just buy replacements for these?
    >


    Hopefully you can and this might be your cheapest option but also
    consider changing the smallest sprocket size if it has more than 11
    teeth if you want to go abit faster. You might also want to consider a
    whole new cassette if this option isn't much dearer. You'll definitely
    need a new chain. I don't know what the current best value chain is
    for quality and competitive pricing but it probably won't be a shimano
    at least at the bottom end of the price scale.
     
  17. On Mon, 13 Dec 2004 20:36:20 +0900, James Annan
    <[email protected]> wrote:

    >Martin Wilson wrote:
    >
    >
    >>
    >> Personally I think your not firing on all
    >> cyclinders if you think load isn't a factor with regard chain and
    >> cassette wear even if its not the main factor but hopefully if you
    >> read some real world experiences you might think differently.

    >
    >Personally I think you're not firing on all cyclinders if you prefer to
    >make up some feeble straw man rather than just read what I said, which
    >was neither ambiguous nor inaccurate.
    >


    Make up some straw man? Never heard of this before and frankly don't
    know what your talking about. I've seen enough of loads effecting
    chain wear to know its a factor even if its not the main factor its
    still significant in many situations. To almost eliminate load from
    the formula for chain wear just seems highly illogical. You know
    yourself that if that the load kept increasing there would at least
    come a point where it was significant. The OP has high levels of wear
    on the sprocket most used that has the most load applied. The wear on
    the other sprockets is much, much lighter and from the sound of it
    almost non existant. I assume the same grit and dirt moves with the
    chain and goes round all the sprockets and not just the smallest. I
    don't know the percentage of how much the smallest rear sprocket is
    used compared to the other gears. I suspect quite high but theres
    possibly more chain/teeth contact in the lower gears at any one time.
    Obviously cadence is factor too. Surely though if load wasn't a factor
    the wear and tear of the chain and sprocket teeth would be more
    general across the whole range of cassette gears.
     
  18. soup

    soup Guest

    Donny popped their head over the parapet saw what was going on and said
    > The small cog definitely has some teeth that look more shark-finny
    > than the others; I reckon I need to replace it.
    >

    If only some teeth (on each cog) are affected
    perhaps they are meant to be that shape as an
    aid to shifting. Wear would show on ALL teeth
    (on one cog)


    --
    yours S

    Nihil curo de ista tua stulta superstitione
     
  19. Clive George

    Clive George Guest

    "Donny" <[email protected]> wrote in message
    news:[email protected]
    > soup wrote:
    > >
    > > [snippage]
    > >
    > > 4,000 miles and never a new chain/cassette, is the small cog worn at
    > > all
    > > (shark finning of the teeth) has the chain stretched? If either of
    > > these
    > > apply maybe it's time to think of new ones .

    >
    > The small cog definitely has some teeth that look more shark-finny than
    > the others; I reckon I need to replace it.


    This is almost certainly how they're supposed to be - some of the teeth will
    be shaped to encourage easy gear shifting. Have a look at a new cassette
    before writing yours off.

    > The two smallest cogs on the cassette are separate from the rest so
    > hopefully I could just buy replacements for these?


    Not economically.

    > I guess I'll need a new chain as well?


    This is what should be driving your purchasing decision. If the chain is
    worn/knackered, you should replace it. If it's too far gone, you'll need a
    new cassette as well. But try a chain first.

    I'd recommend an SRAM chain - PC58 or PC59 depending on whether you're 9
    speed or not, and make sure you get the funny link with it. (and practice
    using it off the bike - there is a bit of a knack).

    cheers,
    clive
     
  20. Clive George

    Clive George Guest

    "Martin Wilson" <[email protected]> wrote in message
    news:[email protected]

    > The OP has high levels of wear on the sprocket most used that has
    > the most load applied.


    This is almost certainly not true - what you've diagnosed as wear is
    probably the original shape.
    This puts the rest of your argument out.

    cheers,
    clive
     
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