at work today, rather than actually working. It will be a long afternoon catching up on real work.

I have a Stronglight 93 crankset with 23.35mm threading for dustcaps, so a standard crank pulling tool doesn't work.

JA Stein has a proper tool, available from VeloOrange for $55.


But I'm too cheap to buy one. Instead, I had a single chromed steel dustcap for the cranks, so I thought I might be able to make my own.

First, I drilled out three holes - one for a 10-32 rivnut and two for a pin wrench to install and hold the dustcap during extraction:


Then I countersunk the center hole and notched a keyhole to keep the rivnut from rotating in the dustcap. I also found a couple of washers to get the correct total thickness for the rivnut:


After swaging the Rivnut in place. I also chased the threads on the rivnet, which is why the walls are a bit scrapped up (held it with pliers):


To drive the crank off of the BB spindle, I found a socket-head screw, and added a pair of nuts with a lock washer. Those nuts are 3/8" wide, but seem to accept a 10mm wrench without slipping.


However, the socket head looked too small - I was worried it would go into the BB axle rather than sit on the surface. The simple solution would be to replace the screw with a hex head, but since I didn't have one handy I tried something else:


With the screw withdrawn as far as possible, the plastic cover sits about 1/8" proud of the dustcap thanks to the unthreaded shaft of the screw. Perhaps too far? I'll see what happens this weekend if I have time. I'll definitely scare up a proper hex head screw just in case.



Anyone ever try something similar? Did it work?

Cheers!

I applaud your ingenuity, and wish you success. I finally broke down and bought a Stein - (he sells them direct on eBay for $49 shipped.)

Will the cap have enough strength to not bend during the removal? Not trying to question the idea, I can say with 100% certainty that I've never tested the strength of a dustcap besides stripping out the holes.

If it weren't a steel dustcap, I wouldn't have even bothered. I'm hoping the washers will help spread out the load.

The cranks are currently sitting on my workbench, so I''m starting in a good position: install on a BB with some amount of torque, than try to remove. Repeat with increased torque until within spec or until failure.

I'm pretty sure the plastic cap is going to fail first, so a proper hex head screw is a must, I'd think.

Nice idea, hope it works. But, if at first you don't succeed and don't wish to spend $55 on a Stein puller, try an automotive gear puller. I had a Thun crank with stripped threads. A Harbor Freight 3 arm gear puller worked fine.

There is a trick to using less force on your puller to remove a stubborn crankarm, even if you have a proper tool.

Apply the wrench force to the puller, than straddle the bike and apply weight to the pedals with the crankarms horizontal.
Flip the cranks a few times so as to reverse the torsion loading on the square tapers.

You'll have to repeat the tightening perhaps several times, as each application of wrench force and crank torsion finally creeps the arms off of the spindle.

I am suspicious of the plastic part though, not sure it can sustain the pressure without promptly losing pushing force.
So, if you can get a helper to tighten your bolt while you dance on the pedals, maybe the arm loosens faster.
Oh, and it helps if you're heavy, or if you can apply a downward impact load on the pedals, helps twist the taper more.
And of course a penetrant will also help.

Next time I am out at the main shop I will have to fire up the lathe since my Stronglight puller has gone awol and it would be nice to have my own hand made tool.

Figure that if I am gonna make one, I might as well make a few more.

A gear puller also works although the right tool makes doing the job so much better.

Ingenious, but I don't think the rivnut will stay put if you need to torque down on the bolt.

Idea:
Although this won't be straight forward due to the chroming on the cap, try and weld a nut to the face of the steel cap. The welds will be stronger than the compression of a rivnut.
Plus the hex allows you to attach it to the arms with a wrench, not a pin tool.

The head of the bolt needs to be 11.42mm in diameter to push against the axle. (I measured the Park puller I have here at work.)

Very nice - The little unit looks nice and clean...

Also thanks for the tips...

I think the larger washers will disperse the load.
Time will tell

You might want to "fill" the whole backside of the cap with braze to make it rigid. You can re-drill the holes if that's what you are using to install and remove it.

I have been the victim of the use of pullers (check before you hand over the cash):

Automotive pullers should only be used for cranks with stripped threads.

To the OP....nice ingenuity.

My go to tip for removing stubborn crank arms is to heat them for a few seconds with propane torch, the aluminum expands a tick and they come right off.

Energy is a very useful commodity in all its forms! The PO of the cranks clearly used the wrong vehicle for it.

LOL I have been kind of looking for those caps! As many as have been subjected to deformation, at least there is a possible use for them. I like Otis suggestion too. Let us know how it works.

Heat should be effective in every case where something prevents the arm coming off with the available pulling force.
If it works for a steel cotter crank, it should work much better with an alloy crank, which has much greater thermal expansion.

But did you mean perhaps a few minutes? Alloy sucks up heat all the way down the crankarm, and I would try for 200 degrees or so which might take nearly a few minutes I'd guess. I give steel cotter cranks a minute and a half, at least.

...Or does your propane torch look like THIS:

I mean seconds...like 4 or 5. And its a regular cheap propane tank from HD or WalMart. It work for stuck dust caps to.

If you know someone with a metal lathe, they might be talked into making a puller like the Velo Orange one in the first post. A lathe can make any thread diameter you need, with the required 1mm or whatever thread pitch. It really only needs two flats, not a hex. Any good-sized bolt can be used for the pusher.

Here is how to do it, if you have a lathe.

1. Source the appropriate nut and bolt... am guessing an M16 stud connector (or imperial equivalent) and matching bolt was probably used as the base stock since they are long enough and only cost a few dollars. These are 24mm across the flats so the work to turn it down and thread it would be minimal and would yield very little waste.

2. Turn down the nut to 23.35.

3. Add groove between the threaded portion and the nut, this makes for easier and cleaner threading.

4. Cut the threads 1mm pitch with a .614 depth.

5. Turn down the end of the M16 bolt to 11.42 to fit the axle.

There you go. I was thinking bar stock (which I have plenty of) for the body of the puller, but the stud connector sleeve is a good one that saves several steps.

I've got a lathe and milling machine in my garage shop and find them very handy for repairing or making the parts I'd rather not hunt down and buy, as well as parts that are no longer available. In one of my other hobbies, racing radio controlled gas-powered boats, I make a lot of the running hardware rather than spend the $400, per boat, it would cost to buy it.

Very clever invention CO_Hoya - like everyone else here I hope it does the trick for you.
A lot of good information in this thread BTW...(A little) heat is always an asset when pulling cranks. It will facilitate pulling any crank.

Nasty weather this weekend so I don't think I'll get around to testing my invention just yet.

But I've got a pile of 5/8" & 3/4" bolts at work, and a lathe. Perhaps I'll buy a couple of coupling nuts (stud connectors) and take a shot at the step-by-step after work one day.

Thanks all for the encouragement.

CO,

You know those steel Stronglight dusts caps go for $200-$300 a pair on eBay... even your currently mangled solo piece should fetch $75, enough to buy a proper tool!

I keed... that is a great use of brains and hardware to solve a problem. My standard crank puller is a damaged Park CCP-4 with a missing nose-piece for proper contact with the spindle end. I just stick a big (3/8 or so) ball bearing in place to do what you want the plastic to do. It makes for a nice non-galling interface with the spindle end.

That's hard to believe. I could use the cash right now. My truck's hood needs paint. I got four of them in a bag of parts I paid $17 for on eBay.

That was done by a pry bar.

I just bought a Stronglight branded puller for less than $20. I thought I got a great deal until I realized that it's a standard 22mm puller.