Recalcitrant Pedals

Kieran_Burns

Any ideas how to get some pedals that are basically seized to the crank arm off?

'Gentle' tapping with the hammer just causes the spanner to open (!) and the bolt to start sheering- the only thing I can think is to remove the crank arms and leave the damn things soaked in oil over a weekend

In other news: swapping a BB is a 5 minute job when you have the right tools and the right BB (swapped my mates over last night and after the faff I went through sorting out my Tricross BB, I knew the right size crank (68 x 118mm if'n you're interested) and had the right tools

If anyone has any hints about how to get the damn pedals off though - it would be appreciated.

mudcow007

heat? or penetrating oil? or both

then adjustable spanner (stronger head than a normal spanner) scaffolding pole for mucho leverage

Ben6899

The first thing you need is a quality pedal wrench. Not an adjustable spanner or similar - a flat, open pedal wrench with a decent length handle.

Then if the pedals still won't budge, you need to somehow increase the lever arm - fixing the wrench to an old golf club, top tube or a long piece of 2x4 would do the trick.

This is all speaking from experience. In my case I used the huge knock-on wheel wrench I have for my old MG and slid that over the pedal wrench to multiply the lever arm by about three times. The pedals came straight off with that.

But the real secret is to start with a quality wrench.

EDIT: I see mudcow recommends an adjustable spanner. He is of course correct the head is usually stronger, but unless the adjustable is high quality, then can open under great force and round-off the flats.

EKE_38BPM

As Mudcow says, penetrating oil (it works best if you can get the part vibrating so that the oil can get into all the nooks and crannys) and mucho leverage.
Good tools are a must. My brother buys his tools from Pound shops (slight exageration) and they may as well be made from butter.

Heating a rod in a hole will cause the rod to expand and the hole to become tighter, so try cooling (not freezing) the pedal/crank as this may make the pedal spindle to contract and the thread hole in the crank to get bigger and therefore easier to separate. I have left sticky parts in the fridge overnight and had some success but this isn't really practical with a stuck BB (unless you have access to a walk-in fridge).

rick_chasey

EKE_38BPM wrote:

As Mudcow says, penetrating oil (it works best if you can get the part vibrating so that the oil can get into all the nooks and crannys) and mucho leverage.
Good tools are a must. My brother buys his tools from Pound shops (slight exageration) and they may as well be made from butter.

Heating a rod in a hole will cause the rod to expand and the hole to become tighter, so try cooling (not freezing) the pedal/crank as this may make the pedal spindle to contract and the thread hole in the crank to get bigger and therefore easier to separate. I have left sticky parts in the fridge overnight and had some success but this isn't really practical with a stuck BB (unless you have access to a walk-in fridge).

Should write adult novels with that kind of chat.

thistle_

+1 for heat. Have used it lots of times where the crank was stuck on a square taper BB and with stuck rotor bolts.

Have you taken the crank arm off the BB? If not maybe you could clamp it in a vice and use 2 hands on the spanner.

EKE_38BPM

Rick Chasey wrote:

EKE_38BPM wrote:

As Mudcow says, penetrating oil (it works best if you can get the part vibrating so that the oil can get into all the nooks and crannys) and mucho leverage.
Good tools are a must. My brother buys his tools from Pound shops (slight exageration) and they may as well be made from butter.

Heating a rod in a hole will cause the rod to expand and the hole to become tighter, so try cooling (not freezing) the pedal/crank as this may make the pedal spindle to contract and the thread hole in the crank to get bigger and therefore easier to separate. I have left sticky parts in the fridge overnight and had some success but this isn't really practical with a stuck BB (unless you have access to a walk-in fridge).

Should write adult novels with that kind of chat.

That is my sideline.

EKE_38BPM

OT, but why do people say things like crank arms or front forks? They are cranks and forks.

"PIN number" also bugs me as PIN stands for Personal Idendification NUMBER.
"Okay" is another one that bugs me. "OK" is OK though.

UndercoverElephant

Sometimes the only way to shift a pedal is to have greased it properly in the first place.

Oh, and make sure you're unscrewing it the right way (towards the back of the bike), I hear that some people can get confused and try to do it wrong.

SimonAH

Cooling the shaft is going to be next to impossible (sorry EKE) the theory is to heat the outside of the crank so that the aluminium expands (a hot air gun is ideal) and before the heat transfers to the shaft the differential expansion will make the hole (temporarially) bigger - ergo it can crack off the corrosion locking the two together. This is also a good time to apply penetrating oil as it will wizz into the gap through capilarity.

Then apply torque using (as has been mentioned) a good quality pedal spanner extending the handle length for additional leverage if required.

But before any of this, please perform a sanity double check that you are unscrewing in the correct direction!

rjsterry

Ben6899 wrote:

The first thing you need is a quality pedal wrench. Not an adjustable spanner or similar - a flat, open pedal wrench with a decent length handle.

Then if the pedals still won't budge, you need to somehow increase the lever arm - fixing the wrench to an old golf club, top tube or a long piece of 2x4 would do the trick.

This is all speaking from experience. In my case I used the huge knock-on wheel wrench I have for my old MG and slid that over the pedal wrench to multiply the lever arm by about three times. The pedals came straight off with that.

But the real secret is to start with a quality wrench.

EDIT: I see mudcow recommends an adjustable spanner. He is of course correct the head is usually stronger, but unless the adjustable is high quality, then can open under great force and round-off the flats.

+1 for a big workshop quality pedal wrench. Although if the pedal axle is staring to shear off the threaded end as KB suggests (or did I read that wrong) then you are stuffed. The metal has already failed. If you are lucky, the axle will have an allen socket in theback of the threaded end, but if it's as seized as you say, you will be lucky not to shear off the allen key or allen socket. Good luck.

mudcow007

rjsterry wrote:

The metal has already failed. If you are lucky, the axle will have an allen socket in theback of the threaded end, but if it's as seized as you say, you will be lucky not to shear off the allen key or allen socket. Good luck.

if the nut has rounded an you dont have the allen key on the back of the axle you always take the pedal cage off an get some friendly person to weld something to the axle so you can get it "un done"

depends how much the chainset is worth though??

EKE_38BPM

SimonAH wrote:

Cooling the shaft is going to be next to impossible (sorry EKE)...

Depends how long you cool it for. Stick the crank and pedal in the fridge overnight. That should get everything nicely cooled.

SimonAH wrote:

...the theory is to heat the outside of the crank so that the aluminium expands...

Won't that make the hole tighter? I distintly remember my physics teacher showing the class an experiment where a metal hoop and a metal ball was cooled to expand the hoop slightly and the ball contract to allow the ball pass through the hoop even though it wouldn't at normal room temperature.

This technique is used in the rail industry to get metal tyres onto the wheels on trails. Everything is cooled with liquid nitrogen, the tyre is put on the wheel and then as they return to normal temperatures they wedge tight.
edit: I've just googled it and found a few sites that show me to be wrong, but I remember seeing it in school text books.

SimonAH wrote:

...But before any of this, please perform a sanity double check that you are unscrewing in the correct direction!

+1 (not that I'd ever make that mistake)

greg66_tri_v2.0

EKE_38BPM wrote:

Heating a rod in a hole will cause the rod to expand and the hole to become tighter

How's that work then?

Heat a washer. Imagine it can't melt. It can only get hotter, and as it does it expands.

If the hole gets smaller, eventually it will close up. At the same time the outer circumference will get bigger. So you'll end up with a piece of material expanding to infinity at the outer circumference but crushing itself into a singularity at the centre. Sounds implausible, unless the washer gains mass during the process.

More likely: the outer and inner circumferences increase, until the washer becomes an enormous but thin ring that is just a few molecules thick. Keep going, and the molecules will separate causing the washer to disintegrate.

Kieran_Burns

Thanks folks. These are the original pedals so whatever preparation was made was out of our hands, and we have checked that we're undoing the pedals the right way

I've not complete sheared the pedals, so it's not all lost. I'll go look for a good pedal spanner soonest and we'll have another go.

greg66_tri_v2.0

EKE_38BPM wrote:

I distintly remember my physics teacher showing the class an experiment where a metal hoop and a metal ball was cooled to expand the hoop slightly and the ball contract to allow the ball pass through the hoop even though it wouldn't at normal room temperature.

This technique is used in the rail industry to get metal tyres onto the wheels on trails. Everything is cooled with liquid nitrogen, the tyre is put on the wheel and then as they return to normal temperatures they wedge tight.
edit: I've just googled it and found a few sites that show me to be wrong, but I remember seeing it in school text books.

The physics expt will work if you (a) cool the ball but leave the hoop at room temp; (b) heat the hoop but leave the ball at room temp; (c) (maybe) if you cool or heat both and the hoop has a greater coefficient of expansion.

In the railway thing, is the wheel a different metal to the tyre, with a different expansion rate?

SimonAH

EKE_38BPM wrote:

SimonAH wrote:

Cooling the shaft is going to be next to impossible (sorry EKE)...

Depends how long you cool it for. Stick the crank and pedal in the fridge overnight. That should get everything nicely cooled.

SimonAH wrote:

...the theory is to heat the outside of the crank so that the aluminium expands...

Won't that make the hole tighter? I distintly remember my physics teacher showing the class an experiment where a metal hoop and a metal ball was cooled to expand the hoop slightly and the ball contract to allow the ball pass through the hoop even though it wouldn't at normal room temperature.

This technique is used in the rail industry to get metal tyres onto the wheels on trails. Everything is cooled with liquid nitrogen, the tyre is put on the wheel and then as they return to normal temperatures they wedge tight.
edit: I've just googled it and found a few sites that show me to be wrong, but I remember seeing it in school text books.

SimonAH wrote:

...But before any of this, please perform a sanity double check that you are unscrewing in the correct direction!

+1 (not that I'd ever make that mistake)

Hi EKE,

Firstly a hole in a piece of metal expands and contracts with temperature exactly as if it were solid material - counterintuitive I know, but please take it from me.

To loosen a shaft in a hole you want to either increase the size of the hole, or decrease the diameter of the shaft. The easiest way of doing this is to either chill the shaft to shrink it (without chilling the hole) or heat the hole to enlarge it (without heating the shaft).

If you heat both shaft and hole or chill both shaft and hole then they expand or contract together and remain just as tightly locked (assuming that they are made from the same material and therefore have the same expansion coefficients).

As it happens, here you have two different materials, steel and aluminium. Aluminium has a fairly high coefficient at around 23, steel is lower at around 10. What this means is that aluminium expands much more with heat than steel does (and similarly contracts much more with cold than steel does). In this instance then, heating the whole thing up together will make the shaft as loose as a cock in a sock - but if you can just mostly heat up the outside (ie the hole) then the differential expansion will be that much more magnified.

Putting the whole thing into the freezer will, by comparison, make it tighter than a good catholic girl before marriage.

t4tomo

SimonAH wrote:

good catholic girl

Oxymoron alert. The only good catholic girls are the bad ones surely?

gtvlusso

Crank is more likely to be alloy and the pedal is more likely to be cromoly - @OP please advise.

So, the alloy has a lower melting point and will get hotter quicker than cromo - so, I would, very carefully, heat the crank a little - too much and it may melt.

Lesson #2 - when you next put some pedals on - cover the threads in coppaslip (copper grease) before you fit them. They won't seize on then.

SimonAH

gtvlusso wrote:

Crank is more likely to be alloy and the pedal is more likely to be cromoly - @OP please advise.

So, the alloy has a lower melting point and will get hotter quicker than cromo - so, I would, very carefully, heat the crank a little - too much and it may melt.

Lesson #2 - when you next put some pedals on - cover the threads in coppaslip (copper grease) before you fit them. They won't seize on then.

Aluminium melts at 660C - you're not in much danger here unless you go full-on blow torch! A hot air gun won't go there. Don't get it too hot though as the varnish on the alloy will come off at a relatively lower temperature.

If the shaft does shear off by the way it's not the end of the world. Any competent small engineering firm will be able to get it out for you by drilling most of it out and then using a stud extractor to remove what's left.

EKE_38BPM

SimonAH wrote:

Hi EKE,

Firstly a hole in a piece of metal expands and contracts with temperature exactly as if it were solid material - counterintuitive I know, but please take it from me.

To loosen a shaft in a hole you want to either increase the size of the hole, or decrease the diameter of the shaft. The easiest way of doing this is to either chill the shaft to shrink it (without chilling the hole) or heat the hole to enlarge it (without heating the shaft).

If you heat both shaft and hole or chill both shaft and hole then they expand or contract together and remain just as tightly locked (assuming that they are made from the same material and therefore have the same expansion coefficients).

As it happens, here you have two different materials, steel and aluminium. Aluminium has a fairly high coefficient at around 23, steel is lower at around 10. What this means is that aluminium expands much more with heat than steel does (and similarly contracts much more with cold than steel does). In this instance then, heating the whole thing up together will make the shaft as loose as a fool in a sock - but if you can just mostly heat up the outside (ie the hole) then the differential expansion will be that much more magnified.

I take your word for it and stand corrected. My memory of doing GCSE Physics 20+ years ago must have failed me. I guess it was one or the other (ball and hoop) that got heated/chilled.

SimonAH wrote:

Putting the whole thing into the freezer will, by comparison, make it tighter than a good catholic girl before marriage.

I used to know a good catholic girl in my teenage years. She had very strict, very catholic parents and wasn't allowed out to parties unless adults that they knew were there and definitely not pub or clubs at all.
On the weekend of her seventeenth birthday she was allowed to go to a church 'disco' in central London with some friends. She ended up being impregnated by an Italian exchange student in Hyde Park and was a single mum by the age of 18. Apparently she went from first kiss to impregnated in about three hours.
True story.

DrLex

EKE_38BPM wrote:

[...]I used to know a good catholic girl in my teenage years. She had very strict, very catholic parents and wasn't allowed out to parties unless adults that they knew were there and definitely not pub or clubs at all.
On the weekend of her seventeenth birthday she was allowed to go to a church 'disco' in central London with some friends. She ended up being impregnated by an Italian exchange student in Hyde Park and was a single mum by the age of 18. Apparently she went from first kiss to impregnated in about three hours.
True story.

And that's why I love this forum. I can only offer 2 thoughts - a big pedal spanner makes life easier, and impregnate & impregnable have different roots.

SimonAH

As they used to say about Irish girls "You can take the girl out of Cork, but you can't take the......"

rick_chasey

Lovely use of recalcitrant.

I was called that once by a teacher in a school report.

rjsterry

Rick Chasey wrote:

Lovely use of recalcitrant.

I was called that once by a teacher in a school report.

Never!

rick_chasey

rjsterry wrote:

Rick Chasey wrote:

Lovely use of recalcitrant.

I was called that once by a teacher in a school report.

Never!

I know.

Officious too, right?

Who'd have thought I'd be a mod.

veronese68

Ben6899 wrote:

In my case I used the huge knock-on wheel wrench I have for my old MG and slid that over the pedal wrench to multiply the lever arm by about three times. The pedals came straight off with that.

We sell them. That would definitely give enough leverage. They are about 2 feet long with holes to fit over the ears of the knock-ons that would fit a spanner. Also have flats on them for clumping with a mallet if need be. But at £40 I'd say a decent pedal spanner is a better bet.

rick_chasey

I do fear the day I take my pedals off my '05 Specialized...

Kieran_Burns

Rick Chasey wrote:

I do fear the day I take my pedals off my '05 Specialized...

This a 2010 model Tricross if that makes you feel better. I really am glad I invested in a tub of copper slip.

rick_chasey

Kieran_Burns wrote:

Rick Chasey wrote:

I do fear the day I take my pedals off my '05 Specialized...

This a 2010 model Tricross if that makes you feel better. I really am glad I invested in a tub of copper slip.

....Yeah..... I just whacked them straight in, no grease, no nothing.

Oh well, excuse for N+1 at some point, right?

MonkeyMonster

Rick Chasey wrote:

Lovely use of recalcitrant.

I was called that once by a teacher in a school report.

Distracts others and could do better... more than a few times.