How to stop cranks loosening?

[NickD]

OK, this isn't quite as stupid a question as it seems...

When I'm standing on the pedals (for a gnarly section, hopping over a
kerb etc), I always have my right pedal forward, and the left at the
back. Dunno why, but that's just the way it is.

Problem is that my LH crank loosens itself as a result of this. I
retighten it from time to time, but I'm aware that this isn't the best
plan. So what's the best option? Loctite? Torque wrench (not sure about
this, as the bolt can still back itself off)? Something else?

Cheers
Nick

 

[Qui si parla Campagnolo]

NickD wrote:
> OK, this isn't quite as stupid a question as it seems...

No stupid questiopns, just sometimes stupid answers.
>
> When I'm standing on the pedals (for a gnarly section, hopping over a
> kerb etc), I always have my right pedal forward, and the left at the
> back. Dunno why, but that's just the way it is.
>
> Problem is that my LH crank loosens itself as a result of this. I
> retighten it from time to time, but I'm aware that this isn't the best
> plan. So what's the best option? Loctite? Torque wrench (not sure about
> this, as the bolt can still back itself off)? Something else?

First time it loosened it was deformed and you may not ever keep it
tight. Octalink and square taper to a lesser extent is prone to what
you see when the crank is forced in the opposite direction of
pedealing...you are a right foot forward guy, problem will be with the
left/aft crank. New left crank arm, install correctly...at least the
left is cheaper of the two.
>
> Cheers
> Nick

 

[[email protected]]

Nick Drew writes:

> OK, this isn't quite as stupid a question as it seems...

> When I'm standing on the pedals (for a gnarly section, hopping over
> a kerb etc), I always have my right pedal forward, and the left at
> the back. Dunno why, but that's just the way it is.

> Problem is that my LH crank loosens as a result of this. I
> re-tighten it from time to time, but I'm aware that this isn't the
> best plan. So what's the best option? Loctite? Torque wrench (not
> sure about this, as the bolt can still back itself off)? Something
> else?

http://www.sheldonbrown.com/brandt/loosening-cranks.html

There is no solution for "goofy footed" riding other than to relearn
and lead with the left foot... or get different cranks. As you see,
both Shimano and Campagnolo have addressed crank/spindle attachment
with new designs that appear to get rid of that problem.

Jobst Brandt

 

[Sorni]

[email protected] wrote:
> Nick Drew writes:
>
>> OK, this isn't quite as stupid a question as it seems...
>
>> When I'm standing on the pedals (for a gnarly section, hopping over
>> a kerb etc), I always have my right pedal forward, and the left at
>> the back. Dunno why, but that's just the way it is.
>
>> Problem is that my LH crank loosens as a result of this. I
>> re-tighten it from time to time, but I'm aware that this isn't the
>> best plan. So what's the best option? Loctite? Torque wrench (not
>> sure about this, as the bolt can still back itself off)? Something
>> else?
>
> http://www.sheldonbrown.com/brandt/loosening-cranks.html
>
> There is no solution for "goofy footed" riding other than to relearn
> and lead with the left foot... or get different cranks. As you see,
> both Shimano and Campagnolo have addressed crank/spindle attachment
> with new designs that appear to get rid of that problem.

Being strongly right-footed (and left-handed, BTW), I've led with my right
foot since Day 1 on a bike, and have never once had a problem with the left
crank coming loose. (All "older-style" BBs with various taper designs; no
new "external bearings" types yet.)

Granted, I tend to keep my butt planted on the saddle more than most, but I
do unweight it over rough terrain and obstacles, of course. (Every once in
a while I'll put the left foot forward just to try it, but it always feels
awkward and I'm soon back to my natural position.)

Maybe I've just been lucky?

Bill S.

 

[[email protected]]

Bill Sorenson writes:

>>> OK, this isn't quite as stupid a question as it seems...

>>> When I'm standing on the pedals (for a gnarly section, hopping
>>> over a kerb etc), I always have my right pedal forward, and the
>>> left at the back. Dunno why, but that's just the way it is.

>>> Problem is that my LH crank loosens as a result of this. I
>>> re-tighten it from time to time, but I'm aware that this isn't the
>>> best plan. So what's the best option? Loctite? Torque wrench
>>> (not sure about this, as the bolt can still back itself off)?
>>> Something else?

http://www.sheldonbrown.com/brandt/loosening-cranks.html

>> There is no solution for "goofy footed" riding other than to
>> relearn and lead with the left foot... or get different cranks. As
>> you see, both Shimano and Campagnolo have addressed crank/spindle
>> attachment with new designs that appear to get rid of that problem.

> Being strongly right-footed (and left-handed, BTW), I've led with my
> right foot since Day 1 on a bike, and have never once had a problem
> with the left crank coming loose. (All "older-style" BBs with
> various taper designs; no new "external bearings" types yet.)

I think you missed the design feature that prevents this motion and
retaining bolt loosening. If there is no press fit, there is backlash
and it is this backlash that allows rotations large enough to unscrew
the bolt. Square taper attachments do not suffer from this problem
unless run with too little pressure in the taper fit.

> Granted, I tend to keep my butt planted on the saddle more than
> most, but I do unweight it over rough terrain and obstacles, of
> course. (Every once in a while I'll put the left foot forward just
> to try it, but it always feels awkward and I'm soon back to my
> natural position.)

That has nothing to do with reverse torque on the spindle.

> Maybe I've just been lucky?

Not from my perspective.

Jobst Brandt

 

[Werehatrack]

On 16 Jun 2006 02:10:06 -0700, "NickD" <[email protected]> wrote:

>OK, this isn't quite as stupid a question as it seems...
>
>When I'm standing on the pedals (for a gnarly section, hopping over a
>kerb etc), I always have my right pedal forward, and the left at the
>back. Dunno why, but that's just the way it is.
>
>Problem is that my LH crank loosens itself as a result of this. I
>retighten it from time to time, but I'm aware that this isn't the best
>plan. So what's the best option? Loctite? Torque wrench (not sure about
>this, as the bolt can still back itself off)? Something else?

What you're doing is called being goofy-footed (no joke; the habit has
a name), and it results in a reversal of the torque on the BB shaft,
which is the easiest way to work a crank loose. On a square taper,
it's been my experience that this isn't anywhere near as much of a
problem as it is with Octalink...but in both cases, the crank gets
damaged in the process, and each succeeding attempt at retightening
has a shorter lead time to failure. Eventually, the hole will wallow
out or (if it's a square taper) the crank may split from one of the
corners.

In any event, if the left crank has already been run loose, you're
probably too late to save it, but you might as well keep running until
it wallows past the point at which you can ignore the problem. If it
was me, I would apply Loctite to the splines and bolt (if it's
Octalink), or grease to the taper and Loctite to the bolt (if it's
square taper), and shop for a replacement left crank. The most
important thing, however, is to work on changing your standing habits.
Until you stop putting the right foot forward, the problem will not go
away without a different kind of crank set. If the standing habit
isn't subject to change, you'll want to swap to a crank design that
uses a pinch bolt for the left crank. There are several to choose
from, but none are inexpensive yet.


--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Sorni]

[email protected] wrote:
> Bill Sorenson {who?} writes:
{JB wrote:}

>>> There is no solution for "goofy footed" riding other than to
>>> relearn and lead with the left foot... or get different cranks. As
>>> you see, both Shimano and Campagnolo have addressed crank/spindle
>>> attachment with new designs that appear to get rid of that problem.

>> Being strongly right-footed (and left-handed, BTW), I've led with my
>> right foot since Day 1 on a bike, and have never once had a problem
>> with the left crank coming loose. (All "older-style" BBs with
>> various taper designs; no new "external bearings" types yet.)

> I think you missed the design feature that prevents this motion and
> retaining bolt loosening. If there is no press fit, there is backlash
> and it is this backlash that allows rotations large enough to unscrew
> the bolt. Square taper attachments do not suffer from this problem
> unless run with too little pressure in the taper fit.

JFTR, most of my riding has been on Octalink or ISIS attachments. Only my
first hardtail had (still has) square taper.

Bill "and you misspelled my last name, [email protected]" S.

 

[NickD]

Thanks guys. Not much to add except:
- I too have tried biking left foot forward, and it doesn't feel right,
even on roads. On gnarly singletrack it's going to take a loooong time
to relearn that...
- I intend to go with square taper for my new hardtail - suggestion
seems to be that this problem will be less of an issue with square
taper
- I'm aware I need to buy a new crank for my existing bike, and have
found a place that does them. Just need to bite the bullet, really.

Out of interest, if you ride LF forward, doesn't that mean the RH crank
bolt backs off?

Cheers
Nick

 

[Earl Bollinger]

<[email protected]> wrote in message
news:[email protected]...
> Bill Sorenson writes:
>
>>>> OK, this isn't quite as stupid a question as it seems...
>
>>>> When I'm standing on the pedals (for a gnarly section, hopping
>>>> over a kerb etc), I always have my right pedal forward, and the
>>>> left at the back. Dunno why, but that's just the way it is.
>
>>>> Problem is that my LH crank loosens as a result of this. I
>>>> re-tighten it from time to time, but I'm aware that this isn't the
>>>> best plan. So what's the best option? Loctite? Torque wrench
>>>> (not sure about this, as the bolt can still back itself off)?
>>>> Something else?
>
> http://www.sheldonbrown.com/brandt/loosening-cranks.html
>
>>> There is no solution for "goofy footed" riding other than to
>>> relearn and lead with the left foot... or get different cranks. As
>>> you see, both Shimano and Campagnolo have addressed crank/spindle
>>> attachment with new designs that appear to get rid of that problem.
>
>> Being strongly right-footed (and left-handed, BTW), I've led with my
>> right foot since Day 1 on a bike, and have never once had a problem
>> with the left crank coming loose. (All "older-style" BBs with
>> various taper designs; no new "external bearings" types yet.)
>
> I think you missed the design feature that prevents this motion and
> retaining bolt loosening. If there is no press fit, there is backlash
> and it is this backlash that allows rotations large enough to unscrew
> the bolt. Square taper attachments do not suffer from this problem
> unless run with too little pressure in the taper fit.
>
>> Granted, I tend to keep my butt planted on the saddle more than
>> most, but I do unweight it over rough terrain and obstacles, of
>> course. (Every once in a while I'll put the left foot forward just
>> to try it, but it always feels awkward and I'm soon back to my
>> natural position.)
>
> That has nothing to do with reverse torque on the spindle.
>
>> Maybe I've just been lucky?
>
> Not from my perspective.
>
> Jobst Brandt

Cool, thanks for the info. I have this same problem on my airport commuter
bike.
Since I cleaned and regreased the BB, which was dry at the time, I noticed
this same problem myself.
I think I'll try some locktite on the left crank bolt, as I have to use it
for my business trip Monday.
Anyway it has what appears to be a some kind of a early Shimano Octalink
kind of a crank setup.
But the BB has pressed in cups and simple caged bearings and isn't a more
modern sealed bearing BB.
So at the time I figured I couldn't just replace it with something else like
the nice 46 tooth square tapered 3pc crankset I found at my local flea
market bike shop.
I guess I should have tried the crankset to see if it would have fit or not.
But anyway, the left crank arm has that same getting loose problem too.
But it looks like I might have to upgrade to a new Airport commuter bike
later though. I think having it loosen up on me a few times might have
gouged out the crank arm some so it maybe won't stay tight anymore.
Sometimes I wonder if JB weld would work?

My airport commuter bike is a junky old JC Penney 70's era touring bike that
I converted over to a single speed and extended the rear rack to support a
garment bag.
I use this bike for when I need to go on a business trip and have to fly out
and in from the Dallas Forth Worth International Airport here in Texas.
I pedal on over to the airport and chain the bike inside the North Remote
Parking lot. I figured if it looks like a crappy bike no one will mess with
it.
So far so good.
Here are some pics of it
http://s27.photobucket.com/albums/c163/earlwb/Single Speed RoadBike/

 

[dvt]

Earl Bollinger wrote:
> My airport commuter bike is a junky old JC Penney 70's era touring bike that
> I converted over to a single speed and extended the rear rack to support a
> garment bag.
> I use this bike for when I need to go on a business trip and have to fly out
> and in from the Dallas Forth Worth International Airport here in Texas.
> I pedal on over to the airport and chain the bike inside the North Remote
> Parking lot. I figured if it looks like a crappy bike no one will mess with
> it.
> So far so good.
> Here are some pics of it
> http://s27.photobucket.com/albums/c163/earlwb/Single Speed RoadBike/

Nice rack!

--
Dave
dvt at psu dot edu

One of the most time-consuming things is to have an enemy. -E.B. White,
writer (1899-1985)

 

[Alex Rodriguez]

In article <[email protected]>,
[email protected] says...

>- I intend to go with square taper for my new hardtail - suggestion
>seems to be that this problem will be less of an issue with square
>taper

Don't forget that it is important that you tighten the crank properly the
first time and then leave it alone.
----------------
Alex