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Pedal Falls Off

Started by Elisa Francesca Roselli · · Last activity · 18 posts · 945 views

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Road Cycling
Published
16 May 2005
Last activity
16 May 2005
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Elisa Francesca Roselli
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18
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  1. So here I am with my beloved Flyzipper, a Dahon Impulse P21, at the
    doctor's because I didn't know how to change an inner tube (put the
    wheel on backwards). I resumed my commute to work with Behemoth, a
    monstrous Dutch bike.

    As some may recall, the last we heard from Behemoth was when I had some
    strapless mini clips fitted to the pedals to help me get her lumbersome
    weight up the many hills surrounding Paris (which is why, incidentally,
    so few people have Dutch bikes here, as I now know from hindsight).
    Although everyone encouraged me to persist with the mini-clips, I found
    that they made a difficult bike even more unrideable. Behemoth has
    always been very hard to start. The added conundrum of having to thread
    my feet into clips caused a few near-accidents at intersections.

    So I gave up on the clips. Since I no longer have an LBS worthy of the
    name, I simply bought a new pair of pedals and attempted to screw them
    on myself. They are mountain bike pedals and much easier to use, with
    their toothed metal structure, than the awful, eel-slippery sugarloaf
    rubber pedals Behemoth was born with.

    Today is the second time I ride out with Beth since I changed the
    pedals. Puffing up a hill in first gear, I find the going harder and
    harder, and the right pedal showing a sort of assymetric grind, twisting
    my foot a few degrees at every revolution. I carry on, past the top of
    the hill and coast down into a village. Right there in the center of
    town, with a considerate motorist behind me, I abruptly lose the pedal,
    which clatters off onto the pavement. Motorist stops in time not to
    back-end me or crush the pedal, and waits patiently while I gather up
    pedal and Behemoth splattered clear across the road with all the
    contents of her basket.

    Stopped nearby is a builder with a pickup truck and some wrenches of
    appropriate size, who helps me screw the pedal on again. He tightens it
    as much as he can.

    I resume my route but after only a few hundred yards, I can feel the
    pedal going wobbly again. Not wanting to trust indefinitely to the
    kindness of motorists, I decide to walk the remaining 7 km to work.

    Now what? I realize I cannot trust that pedal. By and by, I see no
    reason to trust the other pedal either. Is it that the thread where it
    screws in is shot, due to my inability to screw it on straight in the
    first place? (For I am constitutionally incapable of screwing straight.
    Read into that whatever you please.) Does this mean replacement of not
    just pedals but also pedal cranks? Or is there any endemic reason why
    one cannot have steel MTB pedals on a aluminum cranks?

    Evidently not my week for cycling.

    Elisa Francesca Roselli
    Ile de France

  2. On 16/5/05 8:22 am, in article [email hidden],

    Elisa Francesca Roselli said:

    Now what? I realize I cannot trust that pedal. By and by, I see no
    reason to trust the other pedal either. Is it that the thread where it
    screws in is shot, due to my inability to screw it on straight in the
    first place? (For I am constitutionally incapable of screwing straight.
    Read into that whatever you please.) Does this mean replacement of not
    just pedals but also pedal cranks? Or is there any endemic reason why
    one cannot have steel MTB pedals on a aluminum cranks?

    Sounds like you cross threaded the pedal first time and stripped the
    threads. Was it hard to put on the first time you did it?
    Did you screw it in the right way (the right hand pedal screws in the other
    way than the left hand one.)

    ...d

  3. David Martin a écrit :

    Quoted message said:

    On 16/5/05 8:22 am, in article [email hidden],
    "Elisa Francesca Roselli" <[email hidden]> wrote:

    Quoted message said:

    Sounds like you cross threaded the pedal first time and stripped the
    threads. Was it hard to put on the first time you did it?

    Yes, that's probably it. I did have a hard time screwing them in.

    Can a pedal that has been cross-threaded and ridden (further damaging
    the thread) still be used safely?

    Elisa Francesca Roselli
    Ile de France

  4. Elisa Francesca Roselli said:

    Now what? I realize I cannot trust that pedal. By and by, I see no
    reason to trust the other pedal either. Is it that the thread where it
    screws in is shot, due to my inability to screw it on straight in the
    first place?

    Sounds entirely possible from the description, so you'll quite possibly
    need a new crank arm on the wobbly side, but to check that use the old
    pedal for a few circuits of the block where you live and see if that's
    okay. If it is then just a new pedal should suffice.

    Quoted message said:

    Or is there any endemic reason why
    one cannot have steel MTB pedals on a aluminum cranks?

    No, pedals are pretty much freely interchangeable.

    The only Sneaky Bit is that the left pedal has a reversed thread, so
    tightens up anticlockwise. There is often, but not always, a G/D or R/L
    indicator, but otherwise it's a case that if it won't go on, you've got
    the wrong one... It's best to put a little grease on the threads before
    putting the pedals on, as that way they'll come off again when you want
    without requiring two days of penetrating oil, a [censored] Size pedal
    spanner and a team of trained body builders. The reason for the
    reversed LH thread is that the act of pedalling should naturally tighten
    both sides, so you don't have to worry about the grease making them
    spontaneously fall off.

    Pete.
    --
    Peter Clinch Medical Physics IT Officer
    Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
    Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
    net [email hidden] http://www.dundee.ac.uk/~pjclinch/

  5. Elisa Francesca Roselli said:

    David Martin a écrit :

    Quoted message said:

    On 16/5/05 8:22 am, in article [email hidden],
    "Elisa Francesca Roselli" <[email hidden]> wrote:

    Quoted message said:

    Sounds like you cross threaded the pedal first time and stripped the
    threads. Was it hard to put on the first time you did it?

    Yes, that's probably it. I did have a hard time screwing them in.

    Can a pedal that has been cross-threaded and ridden (further damaging
    the thread) still be used safely?

    I wonder if you some how got the pedals switched. The right pedal
    should screw in clockwise, and the left pedal should screw in
    counterclockwise.


  6. Quoted message said:
    Quoted message said:

    Can a pedal that has been cross-threaded and ridden (further damaging
    the thread) still be used safely?

    As a paperweight? Or as something to throw at errant dogs/taxi drivers?

    Typically the pedal will suffer no damage through being cross threaded but
    the crank will be shot. This is in accordance with murphy's law of
    engineering maintenance:

    "If two components are assembled incorrectly, the cheaper and easiset to
    replace will be undamaged but the more expensive and harder to replace will
    be a write-off."

    ...d

  7. David Martin a écrit :

    Quoted message said:

    "If two components are assembled incorrectly, the cheaper and easiset to
    replace will be undamaged but the more expensive and harder to replace will
    be a write-off."

    Oh dear. They may have trouble finding a replacement crank for this rare
    imported bike. And walking her back to her dealer in the 16th
    arrondissment will take the better part of an afternoon.

    At least I had the sense to wear my pedometre this morning. So I can
    still quantify the exercize.

    EFR
    Ile de France

  8. Elisa Francesca Roselli said:

    Oh dear. They may have trouble finding a replacement crank for this rare
    imported bike.

    No, cycle transmissions, and especially bits of them like crank arms,
    are interchangeable to quite a high degree. Much like wheels, tyres, etc.

    There shouldn't be any trouble getting it replaced at any bike shop that
    has heard of spare parts.

    Pete.
    --
    Peter Clinch Medical Physics IT Officer
    Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
    Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
    net [email hidden] http://www.dundee.ac.uk/~pjclinch/

  9. Jim Smith said:
    Elisa Francesca Roselli said:

    David Martin a écrit :

    Quoted message said:

    On 16/5/05 8:22 am, in article


    [email hidden],

    Quoted message said:
    Quoted message said:
    Quoted message said:

    "Elisa Francesca Roselli" <[email hidden]> wrote:

    Quoted message said:

    Sounds like you cross threaded the pedal first time and stripped
    the threads. Was it hard to put on the first time you did it?

    Yes, that's probably it. I did have a hard time screwing them in.

    Can a pedal that has been cross-threaded and ridden (further
    damaging the thread) still be used safely?

    I wonder if you some how got the pedals switched. The right pedal
    should screw in clockwise, and the left pedal should screw in
    counterclockwise.

    Cross-threading is one thing, but if the pedals were offered up on the
    wrong side I don't see how Elisa Francesca would have got them to go on
    at all.

    --
    Dave...

  10. On 16/5/05 12:22 pm, in article
    [email hidden], "dkahn400"

    Quoted message said:
    Jim Smith said:
    Elisa Francesca Roselli said:

    David Martin a écrit :
    > On 16/5/05 8:22 am, in article


    [email hidden],

    Quoted message said:
    Quoted message said:

    > "Elisa Francesca Roselli" <[email hidden]> wrote:

    > Sounds like you cross threaded the pedal first time and stripped
    > the threads. Was it hard to put on the first time you did it?

    Yes, that's probably it. I did have a hard time screwing them in.

    Can a pedal that has been cross-threaded and ridden (further
    damaging the thread) still be used safely?

    I wonder if you some how got the pedals switched. The right pedal
    should screw in clockwise, and the left pedal should screw in
    counterclockwise.

    Cross-threading is one thing, but if the pedals were offered up on the
    wrong side I don't see how Elisa Francesca would have got them to go on
    at all.

    My guess would be a slightly undersized pedal thread and oversized crank
    thread, cross threading and hence stripping of the crank thread.

    ...d

  11. dkahn400 said:


    Cross-threading is one thing, but if the pedals were offered up on the
    wrong side I don't see how Elisa Francesca would have got them to go on
    at all.

    You are forgetting that the designers of foolproof systems always
    underestimate the ingenuity of fools ;-)

    --
    Tony

    "A facility for quotation covers the absence of original thought" Lord
    Peter Wimsey (Dorothy L. Sayers)

  12. dkahn400 said:
    Jim Smith said:
    Elisa Francesca Roselli said:

    David Martin a écrit :
    > On 16/5/05 8:22 am, in article


    [email hidden],

    Quoted message said:
    Quoted message said:

    > "Elisa Francesca Roselli" <[email hidden]> wrote:

    > Sounds like you cross threaded the pedal first time and stripped
    > the threads. Was it hard to put on the first time you did it?

    Yes, that's probably it. I did have a hard time screwing them in.

    Can a pedal that has been cross-threaded and ridden (further
    damaging the thread) still be used safely?

    I wonder if you some how got the pedals switched. The right pedal
    should screw in clockwise, and the left pedal should screw in
    counterclockwise.

    Cross-threading is one thing, but if the pedals were offered up on the
    wrong side I don't see how Elisa Francesca would have got them to go on
    at all.

    Unlikely, yes. However, I just recently took an old frame I had just
    acquired to the local bike shop to have the bottom bracket threads
    chased. I decided to have the work done because the BB didn't want to
    screw in easily, and some of the threads looked a bit funky. The work
    was completed as I wandered around the shop, and I took the frame
    home. Sure enough, the frame had nice clean right hand threads on the
    right side, and nice clean left hand threads on the left side. The
    kid who had screwed the taps in and the frame up had nothing to offer
    in his defense other than his adamant claim that the taps screwed in
    with very little resistance.

  13. Elisa,

    I expect when you replaced the pedal you did not tighten it
    sufficiently. As you pedalled precession served to work the pedal
    loose. Unfortunately as the pedal became very loose the axis it rotated
    on becomes magnified (forms a cone) and it efficiently strips the
    threads in the crank (the pedal axle is steel and the crank soft
    alloy). Then the pedal drops off (or comes away with your foot if
    clipless). When you come to replace it there isn't enough thread and
    the pedal won't tighten onto the crank.

    Repair of the crank requires a Helicoil to be fitted. This is a big
    thick washer which is threaded on the outer and inner surfaces. A
    competent bike shop should be able to fit this by drilling and
    threading a larger hole for the helicoil and screwing the pedal into
    the new thread. The final repair will be indistinguishable from new and
    next time be sure to tighten the pedal with a longer spanner.

    Although pedals are reverse threaded to tighten onto the crank when
    pedalling, they need to be pretty tight to start with, otherwise the
    above can happen.

    This gem of information was brought to from the encyclopaedia of
    cycling (ahem) experience...Took 6 miles and a stronglight 80 crank (if
    anyone is interested)
    ..
    Kind regards,

    Daren
    --
    remove outer garment for reply

  14. [email hidden] a écrit :

    Quoted message said:

    I expect when you replaced the pedal you did not tighten it
    sufficiently. As you pedalled precession served to work the pedal
    loose. Unfortunately as the pedal became very loose the axis it rotated
    on becomes magnified (forms a cone) and it efficiently strips the
    threads in the crank (the pedal axle is steel and the crank soft
    alloy). Then the pedal drops off (or comes away with your foot if
    clipless). When you come to replace it there isn't enough thread and
    the pedal won't tighten onto the crank.

    I believe it was exactly so. There is a luxury LBS just at the bottom of
    the hill on my way home from work, about 2 kms from here. I will walk
    Behemoth there tomorrow (bike shops in France rarely open Mondays) and
    nab a lift home from a cager colleague this evening.

    I hope the people at the shop, which sells Cannondales and such like,
    will understand the term helicoil.

    EFR
    Ile de France

  15. Elisa Francesca Roselli said:

    I hope the people at the shop, which sells Cannondales and such like,
    will understand the term helicoil.

    Say what the problem is, ask them to fix it. Don't worry about exactly
    *how*, especially as they can assess it first hand and transatlantic
    jargon may not be the same.

    Pete.
    --
    Peter Clinch Medical Physics IT Officer
    Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
    Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
    net [email hidden] http://www.dundee.ac.uk/~pjclinch/

  16. In article said:
    dkahn400 said:


    Cross-threading is one thing, but if the pedals were offered up on the
    wrong side I don't see how Elisa Francesca would have got them to go on
    at all.

    You are forgetting that the designers of foolproof systems always
    underestimate the ingenuity of fools ;-)

    In the case of a self-tapping pedal, I think it's not so much the
    ingenuity as the torque required. I once undid a bearing retainer
    on a car part by having two of us jumping on six foot scaffold poles,
    but not many pedal spanners would take that.

    (I recently tore a pedal out of a bike in a LBS because it hadn't been
    put in properly, but since it hadn't been put in properly, only a few
    threads were damaged. Still a bit embarrassing though (and, as it happens,
    a Dahon - pedal had no flats for a spanner, and appeared to need to be done
    up with an Allen key from the other side of the crank).)

  17. In article said:
    Elisa Francesca Roselli said:

    I hope the people at the shop, which sells Cannondales and such like,
    will understand the term helicoil.

    Say what the problem is, ask them to fix it. Don't worry about exactly
    *how*, especially as they can assess it first hand and transatlantic
    jargon may not be the same.

    And a new crank may well be cheaper than having the old crank tapped and
    an insert put in. Which pedal was it?

    (Though if you have managed to get the pedals the wrong way around, you
    will almost certainly have damaged both cranks, even if only one pedal has
    precessed loose.)

  18. Elisa Francesca Roselli said:

    (For I am constitutionally incapable of screwing
    straight. Read into that whatever you please.)

    Thank you for a wonderful line. (Will leave others to attend to your pedal
    woes.)

    Bill "familiar with the phrase" S.

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