Here we go again

Thick Mike

bompington wrote:

Starting to think that the problem might have been that it wasn't tight enough and worked loose - I have had trouble with seized pedals before, so whenever I've put pedals on recently I've used plenty of grease and not overdone the tightening. So I guess underdoing the tightening must be it.
New crankset and pedals now on their way as they were getting on a bit, I'll consider the helicoil thing & reconditioning for next time.

This might be the issue, too much grease will provide more resistance as you tighten. It might give you the impression that the pedal is tightened adequately when actually the grease is filling the threads and compressing.

ugo.santalucia

Thick Mike wrote:

bompington wrote:

Starting to think that the problem might have been that it wasn't tight enough and worked loose - I have had trouble with seized pedals before, so whenever I've put pedals on recently I've used plenty of grease and not overdone the tightening. So I guess underdoing the tightening must be it.
New crankset and pedals now on their way as they were getting on a bit, I'll consider the helicoil thing & reconditioning for next time.

This might be the issue, too much grease will provide more resistance as you tighten. It might give you the impression that the pedal is tightened adequately when actually the grease is filling the threads and compressing.

... please...

you have surely noticed the crank has a hole, so any grease in excess will pop out on the opposide side. grease increasing resistance is a first for me... it is used for exactly the opposite reason

bbrap

Thick Mike wrote:

bompington wrote:

Starting to think that the problem might have been that it wasn't tight enough and worked loose - I have had trouble with seized pedals before, so whenever I've put pedals on recently I've used plenty of grease and not overdone the tightening. So I guess underdoing the tightening must be it.
New crankset and pedals now on their way as they were getting on a bit, I'll consider the helicoil thing & reconditioning for next time.

This might be the issue, too much grease will provide more resistance as you tighten. It might give you the impression that the pedal is tightened adequately when actually the grease is filling the threads and compressing.

Not a good idea to suggest the issue might be something when it cannot possibly be the case. The only way grease can provide resistance is when used on a very fine thread into a blind hole (one that does not go all the way through). And even then it will not manifest itself unless the grease is very viscous and the hole has been filled with the stuff.

Thick Mike

Fair enough, I was thinking more about viscous shear resistance...but you're right. Just searching round for a possible cause.

The Rookie

If that was your thinking (while ignoring metal to metal friction) probably best not to think too much.

Greasing/oiling threads actually increases the risk of over tightening as the torque required to achieve the preload (which is what you are actually trying to set) decreases.

Thick Mike

The Rookie wrote:

If that was your thinking (while ignoring metal to metal friction) probably best not to think too much.

Greasing/oiling threads actually increases the risk of over tightening as the torque required to achieve the preload (which is what you are actually trying to set) decreases.

Yes...I said...fair enough!

I was just trying to think outside the box as there doesn't seem to have been a good cause proposed for the repeating nature of this problem. My thinking was that overloading the threads with viscous grease would increase the torque required slightly when tightening by hand.

Anyway...

homers_double

Pedals. Finger tight then a quarter turn with a spanner. There is a reason some threads go in different directions.

bompington

homers double wrote:

There is a reason some threads go in different directions.

On this forum they all do, but I'm not sure I can always see the reasons

homers_double

Hah, good point!

Moonbiker

http://www.velominati.com/tradition/los ... iant-gear/

mashing = low cadence

dennisn

fat daddy wrote:

it may not have been cross threaded .. infact it doesn't sound like it was

googling stripped pedals would seem to point to pedals becoming loose and slowly boring their way through the threads as people don't notice they are loose.

the answer seems to point to - don't use anti-seize, just use grease, you don't want you pedals becoming loose.

I kind of go along with this. I'm also not sure how anyone could cross-thread pedals on. Slowly coming loose and ripping the crank-arm threads up seems very viable.

veronese68

I don't dispute this, it seems the most plausible. But does this mean that pedals don't need reverse threads? Or have they always been done the wrong way? I know cars with centre lock wheels have opposite threads and it does make a difference, they do come undone if the wrong hub is fitted to the wrong side. But if fitted correctly they don't come undone, even with anti seize.

hsiaolc

Its so crazy. never happened to any of my bikes.

Can't cross thread if you did the right pedal to the correct side and hand tight before you torque up with a wrench.

I only seen my colleague broke his crank arm twice in 20 years due to his shear power (fixy) but never seen pedals fall off like that.

cycleclinic

anti seize should be used on pedal threads. There is no need to torque pedals either with a torque wrench. Just getting them hand tight and then a bit more is enough thats about 40Nm. My garmin pedals are torqued to 38Nm. If a pedal is fitted only hand tight or to low torque it can work loose, this is the most likely way this kind of failure can happen.

I forget how many cassettes I have fitted to alloy freehubs never has one stripped. 40Nm is not alot if the threads are in good condition. If they are not then that is different. A good mechanic has feel for these things.

Also metal can fail, it is unlikely but cranks do break so why not pedal threads.

Matthewfalle

fat daddy wrote:

it may not have been cross threaded .. infact it doesn't sound like it was

googling stripped pedals would seem to point to pedals becoming loose and slowly boring their way through the threads as people don't notice they are loose.

the answer seems to point to - don't use anti-seize, just use grease, you don't want you pedals becoming loose.

Grease will make things come loose - it's designed to keep things moving. Anti seize is designed to stop things that don't move seizing which is why it's gritty.

bompington

Update:
New crankset duly bought and fitted, no problems.

Except that something seems to be coming a bit loose. I've recently noticed some play in the cranks: it feels scarily like how the pedal felt when it started coming off.
The pedals are definitely in fine and the cranks are bolted together good & tight. But it feels like the axle between the cranks is too small on the drive side and so can move around inside the BB - it doesn't feel loose on the other side though.

I'm fairly sure that this has developed since I fitted it - it's done a few hundred miles or so and I've only noticed it in the last 60 or so.

So is it:
1. I did something wrong fitting it - did I miss something?
2. The crankset is in some way incompatible with the BB
3. The BB needs replacing as well

It's a SRAM GXP crankset, the old one was Force1 and the new one Rival1 but otherwise identical as far as I can tell.

Any clues appreciated.

darkhairedlord

As others posted on page one, you wore the bike out, not just the crank.
Anyway, did you really just put a new crankset on but not a new BB?

keef66

bompington wrote:

Update:
New crankset duly bought and fitted, no problems.

Except that something seems to be coming a bit loose. I've recently noticed some play in the cranks: it feels scarily like how the pedal felt when it started coming off.
The pedals are definitely in fine and the cranks are bolted together good & tight. But it feels like the axle between the cranks is too small on the drive side and so can move around inside the BB - it doesn't feel loose on the other side though.

I'm fairly sure that this has developed since I fitted it - it's done a few hundred miles or so and I've only noticed it in the last 60 or so.

So is it:
1. I did something wrong fitting it - did I miss something?
2. The crankset is in some way incompatible with the BB
3. The BB needs replacing as well

It's a SRAM GXP crankset, the old one was Force1 and the new one Rival1 but otherwise identical as far as I can tell.

Any clues appreciated.

Being a 100% Shimano type I'm only going by what I've gleaned on here, but I gather some SRAM chainsets use a spindle that's 24mm both sides, and some use a spindle that steps down to 22mm just before the NDS bearing. Could it be you have the BB for the first but the second type of chainset??

dennisn

bompington wrote:

Update:
New crankset duly bought and fitted, no problems.

Except that something seems to be coming a bit loose. I've recently noticed some play in the cranks: it feels scarily like how the pedal felt when it started coming off.
The pedals are definitely in fine and the cranks are bolted together good & tight. But it feels like the axle between the cranks is too small on the drive side and so can move around inside the BB - it doesn't feel loose on the other side though.

I'm fairly sure that this has developed since I fitted it - it's done a few hundred miles or so and I've only noticed it in the last 60 or so.

So is it:
1. I did something wrong fitting it - did I miss something?
2. The crankset is in some way incompatible with the BB
3. The BB needs replacing as well

It's a SRAM GXP crankset, the old one was Force1 and the new one Rival1 but otherwise identical as far as I can tell.

Any clues appreciated.

Nothing personal, but I'm questioning your abilities to do the job right.

keezx

keef66 wrote:

Being a 100% Shimano type I'm only going by what I've gleaned on here, but I gather some SRAM chainsets use a spindle that's 24mm both sides, and some use a spindle that steps down to 22mm just before the NDS bearing. Could it be you have the BB for the first but the second type of chainset??

SRAM GXP 24 mm axle is ALWAYS 22/24 mm , no exceptions.
The system clamp the LH bearing between crank and 24 mm part is normally idiot proof, but some idiots manage to mess up even this simple setup.

veronese68

Is there something weird about GXP as they seem to have more problems reported on here? Is it a set up issue or are they made of chocolate?

keef66

I think the bearings may be smaller or the sealing worse than the corresponding Shimano? That's just wild speculation based on a statistically insignificant number of posts I've read on here and elsewhere. But I have formed the impression that GXP BBs can be very short lived...

My only direct experience has been with Shimano BBs. I had an Octalink LX cartridge BB in a mountain bike that was still spinning smoothly after 10 years of abuse. The 105 Hollowtech BB on my road bike lasted 3 years of year round riding before it developed an annoying click. It was still functional and felt smooth when spinning the cranks by hand, but I replaced it with an Ultegra one just because CRC were selling them cheaply. That's still fine after 6 years. The press-fit Shimano BB in my summer bike is still smooth and silent after 4 years, but I expect that to last indefinitely since it's hardly ever out in the wet.

Hinaultscrapcousin

Veronese68 wrote:

Is there something weird about GXP as they seem to have more problems reported on here? Is it a set up issue or are they made of chocolate?

Nope, not weird at all. They're made by Sram...

keezx

IMO GXP is the best of all outboard systems as no preload or messing with spacers is required.
The bearings are sufficient for years when water&dirt is kept out (which applies for all bearings) and fitting is done properly.
Couple years ago I bought a 2nth hand GXP crankset with a allready used BB, and as we speak this thing is still running fine (app. 15000 km done) , I don't use it in the winter, that's the domaine of square taper stuff.

veronese68

Keezx wrote:

I don't use it in the winter, that the domaine of square taper stuff.

That's quite a limiting factor given the UK weather.

bompington

Seems like the BB is the issue. Silly me for thinking that a bike marketed as CX would be capable of dealing with dirt and water! It has been through wheel-high flood water more than once, and BB-high lots. Is it supposed to be for indoor use only or something?
I'll get a new one (SRAM GXP BB English thread 68mm, I presume there's no other variation I need to know about?) and then see if I can make sense of the whole spacer or not thing - a bit more searching has increased rather than solved the confusion...

keezx

You cannot expect a water flooded BB to last long without any service afterwards, these things are never complete waterproof.
Cover the bearings in- and outside with thick grease might extend the life a bit.
Best for those circumstances is a cheap square taper sealed cartridge BB en fit a new one when it gets rough.

bompington

Worth mentioning that there is no noise or resistance coming from the BB though :?

keezx

Well, IF you have a problem, it's apparenly not the BB bearings.....
One remark on GXP bearings (original SRAM/Truvativ):
The recent models tend to have a LH bearing which is 22,2 mm internal, so the 22,0 axle tends to move a little bit and can make noises some time after fitting. Strange move from SRAM.....probably due to a different manufacturer (SRAM doesn't make anything)
I solved this by applying 1 layer of teflon tape on the 22,0 mm axle stub before sticking the axle through the bearings.
Never had any further problems.

Moonbiker

thoose gxp bb are only good for summer

viewtopic.php?t=13016036

also read from manual p32 says; sevice every 100hrs time or after each ride in the rain.