@#$$ what do I do now? - stripped crank

[Jules]

Ah didn't get that, JB. I have attached the bike to my indoor trainer and will try ride it off. Will give up after three hours

[javadude]

Sorry to Hijack your post Jules, but will one of those bearing puller work for getting the bearings off an Ultra Torque crank?

 

I bought some Token hybrid ceramic bearings and want to give them a try, but have no idea how to get the existing bearings off.

[Wyatt Earp]

 

Thanks Summit' date=' what can I expect to pay for one of those? [/quote']

 

Jules, as I mentioned, they're three-armed and the crank four or five. It is simply not compatible since you can't get the arms in there. However, I have several of them, from small to large, you're welcome to come and try.

 

 

Trust me , I have done it before Bornman.

 

[Speed Devil]

Jules, you you also try wedging a gwala or tyre lever at the back of the crank (over the BB through the frame) and hitting it off with a hammer.

 

Thats what we did in the old days before discovering crank extractors

[Johan Bornman]

Thanks Summit' date=' what can I expect to pay for one of those? [/quote']

 

Jules, as I mentioned, they're three-armed and the crank four or five. It is simply not compatible since you can't get the arms in there. However, I have several of them, from small to large, you're welcome to come and try.

 

 

Trust me , I have done it before Bornman.

 

OK Bosman, I trust you...but before I allow you to work on my bike, study these pictures and tell me how you got your "beeeeeg bearing puller" in between the 5-star spider's legs.

 

 

This photo represents a standard 5-leg crank. The bearing puller is placed on top and reaches into the third dimension towards you, picture taken almost dead from the top.

 

1) In the 8-o'clock position is the first leg of the puller, right between two adjacent spider legs.

 

2) In the four-o'clock position, is the second leg of the puller, right between two adjacent spider legs.

 

3) In the (almost) twelve-o'clock position is the third puller leg, slap bang on top of a spider leg.

 

No matter how you maneuvre this configuration, you always end up with this dilemma. Same for a four-leg spider.

 

A six-leg spider works perfectly, but then again, I haven't seen one of those yet.

 

 

Here's a close-up photo of the pulley and spider leg clashing.

\

\

 

I've now taken the photo from the other side and what was the 12-o'clock position is now the four-o'clock positon, clearly showing the clash of legs. If you look at the adjacent leg, you can see how it should fit.

 

 

Fact is, a three or even four-legged bearing puller does not fit onto a crank.

 

So Bosman, before I trust you, please explain this little geometric puzzle?

 

 

 

Johan Bornman2008-12-07 11:44:30

[Johan Bornman]

Ah didn't get that' date=' JB. I have attached the bike to my indoor trainer and will try ride it off. Will give up after three hours [/quote']

 

OK, time's up! Stop riding.

 

Oops, the crank is still stuck? 

 

 

Cranks are funny things and don't work like people expect them to work.

 

A press-fit crank like the one you're having trouble with is really strange. The BB axle is ground to a 2 degree taper with four sides. The crank has a parallel-sided four-side hole that presses onto the taper, using the crank bold to drive it up the taper.

 

In the process, the aluminium stretches and the steel compresses. When you stop turning the bolt, the crank is in equilibrium with the crank bolt perfectly countering the force from the two metals wanting to squeeze it back to where it came from. However, the bolt is nice and tight and wont budge and, the equilibrium is born.

 

Now you go for a ride. By pushing on the crank you are relieving the pressure on the trailing edges of the taper and increasing the pressure on the leading edges. This process makes the crank squirm further onto the axle by relieving internal stresses during the pedal stroke. It squirms further up the axle to a point where the bolt becomes relatively or completely loose (depending on how hard you pedal). By now it has reached an equilibrium withough the aid of the bolt and unless you perform another very hard pedal stroke, exceeding all others in magnitude, it won't budge anymore and you can remove the crank bolt and ride like that forever.

 

However, if the crank bolt was not tight enough to start off with, it will see the crank move up, loosen the bolt and move down again, enough to work the crank loose again. These cranks are then usually ruined.

 

I think your crank is of the former type and will never come off unless you use some sort of destructive method.

 

But keep us posted, these things are interesting.

 

 

[Ox_Wagon]

That is why I bought a 2 leg puller.

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I have removed a 4 arm with a 3 leg puller and also removed it again with the two legged one.  Yes, it is a bit of a finicky exercise but at least I could re-use the crank and the BB. 

 

Westdene Cycles as also removed a 5 arm crank for me a couple of years ago with out to much hassle (while I waited) but I do not no what they used.

 

The moral of the story is by the best crank puller that you can afford.

[Jules]

Veloce's story reminded me of my own crank-pulling woes. Just thought I'd let hubbers know that this thread has a happy ending. Last Friday, a friend of mine managed to pull off my crank using a two-arm bearing puller.

 

 

 

Soon my Colnago will be fitted with Campy Centaur components and a Rolls saddle

[Wyatt Earp]

 

OK Bosman' date=' I trust you...but before I allow you to work on my bike, study these pictures and tell me how you got your "beeeeeg bearing puller" in between the 5-star spider's legs.

 

?

 

 

?

 

This photo represents a standard 5-leg crank. The bearing puller is placed on top and reaches into the third dimension towards you, picture taken almost dead from the top.

 

?

 

1) In the 8-o'clock position is the first leg of the puller, right between two adjacent spider legs.

 

?

 

2) In the four-o'clock position, is the second leg of the puller, right between two adjacent spider legs.

 

?

 

3) In the (almost) twelve-o'clock position is the third puller leg, slap bang on top of a spider leg.

 

?

 

No matter how you maneuvre this configuration, you always end up with this dilemma. Same for a four-leg spider.

 

?

 

A six-leg spider works perfectly, but then again, I haven't seen one of those yet.

 

?

 

?

 

Here's a close-up photo of the pulley and spider leg clashing.

 

\

 

\

 

?

 

I've now taken the photo from the other side and what was the 12-o'clock position is now the four-o'clock positon, clearly showing the clash of legs. If you look at the adjacent leg, you can see how it should fit.

 

?

 

 

?

 

 

 

Fact is, a three or even four-legged bearing puller does not fit onto a crank.

 

?

 

So Bosman, before I trust you, please explain this little geometric puzzle?

 

?

 

?

 

?

[/quote']

 

I can't believe I missed this, just shows how quickly I loose interest in boring issues.

 

The answer is quite simple, get a smaller bearing puller, Bornman.

 

Why should it actually grab the arms on the spider ?

 

Ohh, I wouldn't want to work on YOUR bike in any case.

 

 

 

Well done Jules, I am glad that my original tip worked.

 

Summit Cycles2009-03-09 06:27:07