Pedal Falls Off

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

On 16/5/05 8:22 am, in article ,
"Elisa Francesca Roselli" wrote:

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

David Martin a écrit :
On 16/5/05 8:22 am, in article ,
"Elisa Francesca Roselli" 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?

Elisa Francesca Roselli
Ile de France

Elisa Francesca Roselli wrote:

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.

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 ******* 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 http://www.dundee.ac.uk/~pjclinch/

Elisa Francesca Roselli writes:

David Martin a écrit :
On 16/5/05 8:22 am, in article ,
"Elisa Francesca Roselli" 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?

If the thread is trashed then you'll probably have to replace the
crank or get a helicoil (thread repair) fitted to it. Depends how
much you'd like to keep the original crank in the future but I'd be
tempted to bond the pedal in to the crank using JB Weld seeing as it's
pretty much a write-off in any case.

Chris
--
Chris Eilbeck
MARS Flight Crew http://www.mars.org.uk/
UKRA #1108 Level 2 UYB
Tripoli UK Member #9527 LSMR

Elisa Francesca Roselli wrote:


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.


if the new pedals are much harder to screw in than the old ones were to
remove, you were probably doing something wrong. The best ways to screw
in a pedal is to hold it with one hand, and to twist the spindle with
the backend of a hexkey.

possible causes for your problems
Pedal not threaded in straight, see fitting method above
pedals put in backwards: see if you can find markings around the
padalflats L shoeld be er.... left etc
wrong thread, with your luck it is not impossible you got french
threaded pedals: you want markings saying 9/16"x24, 14x 1.25 is wrong

First cure is to remove the pedals, run the appropriate tap to chase the
threads and try again. If that doesn't help either fit new cranks or
have a competent shop replace the thread with an insert. Isn't there a
decent cycling club in your neighbourhood? try phoning them and see if
they can't recommend a decent mechanic
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Elisa Francesca Roselli writes:

David Martin a écrit :
On 16/5/05 8:22 am, in article ,
"Elisa Francesca Roselli" 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.

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

David Martin a écrit :

"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

Elisa Francesca Roselli wrote:

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 http://www.dundee.ac.uk/~pjclinch/