To cut a long story short, I have managed (through a combination of ineptitude and temper) to round off the crank bolt on my GX1 cranks. I was going to replace the whole lot with Shimano stuff as the design of the GX1 cranks has pissed me off for a long time.

After an initial slip with my proper crank bolt Allen key, I removed the self extractor to access the bolt better and tried hammering in a variety of bits and turning them with a long socket wrench. All I have succeeded in doing is to round it out more and more.

I have watched a bit of Youtube stuff and I think I basically have two options. Firstly I will try to tap a punch or flat bladed screwdriver into the bulk of the bolt head to try to chase it around. I don’t reckon this will work, but I will give it a try.

The second option is to drill the head off of the bolt. Does anyone have any helpful tips for this? Do I need to use reverse drill bits, or is that only useful when you are looking to extract the whole bolt? I don’t really mind destroying the crankset, but obviously I don’t want to damage the frame. I have metal drilling bits, but do I need some kind of fancy super hard drill bits?

Any help gratefully accepted. Can’t believe I have managed to end up in this state. Thankfully the bike can still be ridden, it is just that the shonky cranks and BB will get more and more play in them.

I’d try the reverse drill bits first. I’ve been very happy with my set from Screwfix. I’ve removed many bolts, but yours is bigger and my be touger. You’ll save the crank with that method.

Thanks. I will research these reverse drill bits. Presumably if they don’t grab and extract, you keep going until the head comes off?

Stainless steel bolts ?

if you cant extract them you’ll need cobalt bits to drill them out , way harder than hss , your nearest toolstation sells them , use 1mm smaller than the bolt thread diameter

Stainless steel bolts ?

No idea TBH. Whatever comes with GX1. The head of the bolt seems very soft, but as for the shaft, no idea really.

I am getting some bolt extractors from screwfix to see if they will do the job.

Bastard thing!

Once you’ve got the head of the bolt off, have you considered how you’re going to get the crank off? As you’ll still have the bolt in the axle then a crank-puller should work fine. If it all goes wrong then a ball joint remover might be the next tool of choice

Had this myself recently with some really old LX Hollowtech II cranks. One of the cinch bolts was rounded out and as it was well recessed inside the crank arm not many of the traditional methods of getting it out would work.

Resorted to hack-sawing past the bolt then bending the shoulder of the crank i’d cut through away from the bolt so it wasn’t gripping any more.

Took bloody ages. Those Shimano cranks are well made!

I’d try the reverse thread drill bit, or a reverse thread stud extractor.

The head of the bolt seems very soft, but as for the shaft, no idea really.

Think you can be fairly confident the head and shank are made of the same material. 😁

If you’re really not bothered about the cranks, just hacksaw or cut the arms off with an angle grinder.

Once you’ve got the head of the bolt off, have you considered how you’re going to get the crank off?

If I have removed the head I would assume a little bit of ‘persuasion’ would be all that would be required?

My plan (such as it is):

Use the recess to my advantage in the only real way – spray a pool of penetrating oil onto it and leave for a while.

Then try to hammer a punch or flat bladed screwdriver into the edge of the bolt head and try to chase it around and out.

Failing this – it will be carefully drilling a pilot hole a tad too small for the bolt extractor, carefully screwing it in and applying increasing amounts of leverage (and praying a bit).

Forget trying to tap it round, and screw extractors, if it’s tight enough to round out the head then you’ll be wasting your time. Drilling the head off is one option, but don’t expect a left-hand drill to unscrew it until the head is removed to release the tension on the threads. By far the easiest option is to find somebody with a mig or tig welder who’s willing to weld an old allen key into the head (said with the experience of being tasked with this job many times).

https://singletrackworld.com/forum/topic/sram-crank-removal-fiasco/page/2/?links=false%2F%2F%2F

Hopefully it won’t end like this

How about using an impact driver with a flat screw driver bit? The ones you whack with a hammer,not expensive and handy to have in a tool kit anyway

The other crank supported well of course so the frame isn’t stressed.

I recently had to remove a rounded cam pulley bolt. It was a shallow multi point type fixing and a very high strength bolt.
What worked was tungsten carbide drill (insert Monty python sketch) under size followed by a tungsten carbide rotary burr bit for the final removal.
The stub of the bolt left in the cam was finger tight and came out easily.
Can a standard crank extractor not work once the head is off? Failing that a nice new bolt in place of the old bolt then extract as designed.

I’ve had success with cobalt drill bits from toolstation used with cutting oil cooling spray, carefully increasing the bit size to just less that the bolt then used a pick to remove the bits of bolt left, managed to save the threads and pop a new bolt in, I did this after the bolt extractor with reverse thread didn’t work. Its always worth trying a bolt extractor first. If you’re not arsed about the cranks just drill em out with a stepped bit.

I’m getting more worried the more posts I see!

My only priority is to get the bastard out so I can replace the cranks and BB. I am going to stick with my plan above and if necessary just keep going until the bolt is drilled out in its entirety. If absolutely necessary I will borrow an angle grinder and cut the crank off. My only real priority is not to damage the frame, which I love.

Thinking about it now, part of the problem could be the drive side pulling a bit against the bolt. Again, without going into to much detail, the very reason I want to replace these infernal things is the stupid ‘gap’ on the driveside that leads to the bearing cover/insert thingy wearing, walking out and shearing off. To combat this I used some rubber seals to pad out the gap and keep the cover/insert in. These may well add a bit of tension back. It is particularly galling because it is this very trait that has led me want to bin them. Even more so because this would have been the last time I would have had to remove the **** bolt.

I only put it back in a week or so ago until I could get some replacement cranks sorted!

I’m still ruminating on this as I decided to cool down a bit and leave it until after my usual mid-week night ride and weekend ride. I can then dedicate a bit more time to it…..

I am feeling moderately optimistic about the softness of the bolt. When I was whacking various torx heads and screwdriver bits into it, it chewed up really easily. I’m thinking that the bolt extractor has a chance whilst it will be comparatively easy to drill the whole thing out if it fails.

Does anyone actually know what a standard GX1 crank bolt is made of?

Stainless of some sort, probably A2.

Drill bit bigger than the bolt shaft. Drill head off, go for ride down the street if the crank doesn’t just pull off at this point.

Or go nuclear, angle grinder, if nothing else the heat it puts into the crank will get it off the axle as soon as you go through the bolt head. Just put something fireproof over the frame to protect the paint.

Stick to drills and avoid the extractors – if you snap one in there it could be a pain, it might not be but its a sight/feeling to avoid.
l or R handed drill to get the head off , then smaller l/h drill in the centre of the remaining thread should wind it out.

Yes straight to the drill bits.
Sram gx cranks are known for this issue, with them been so bloody tight for some reason!
All the ones I had to remove involved bike on ground, good hex socket 60cm breaker bar and 3 weetabix for breakfast! they bloody tight!!

I bought the extractor set from Screwfix. They rounded off like toffee. 🙁
I drilled mine out and ruined the crank arm in the process.
Swear tin was overflowing that day.

I bought the extractor set from Screwfix. They rounded off like toffee.

I suspect this may happen to me too.

I drilled mine out and ruined the crank arm in the process.

I think this is what I will end up doing. Although I don’t care about the crank – stupid design has burnt its bridges with me.

Swear tin was overflowing that day.

Already looking quite flush after the initial rounding off incident!

Do you have a 15mm or 16mm ish drill bit? (if its on of these https://www.sjscycles.co.uk/chainsets/sram-crank-arm-bolt-m15-m26-alloy-selfextracting-gxp-black/)

Alloy should drill quite quickly/easily, you will then need to pull the crank off the spindle (it should still be a press fit on once the bolt head is removed) , I would use a 2 leg puller, gear puller or similar.

Alloy should drill quite quickly/easily

My hopes are centred around the bolt being described as ‘alloy’. It rounded and chewed up surprisingly easily, so that is what I am clinging on to. If I end up drilling the head off I am going to ‘persuade’ the crank to leave the spindles with a length of broom handle and a hammer.

I just want rid of the whole lot!

I’d just go for a ride once the bolt is off. The action of pedaling will shift it fairly quickly.

Have they changed the design? Mine has a preload collar like the old M970 XTR used to have to take the space up.

GXP was a horrible system with the walking top hat spacers and bearings, solution is to use Hope BB and replace the plastic shield every 800 miles or so, although I reckon just replacing it with a cir-clip would also work.

First things first, thanks to everyone who tried to help, STW is great for stuff like this.

Well, I can confirm that GX1 crank bolts are made of something mild. Cheddar or Wensleydale would be my guess. No need for extractors or shizzle like that. A standard HSS drill bit reduced the bolt head to a small pile of swarf in a little over five minutes and the crank pulled straight off.

Shimano BB and crankset now installed and the GX1 crankset is in a more appropriate place. I.e the dustbin.

Cheers!

Just went to remove my Dub cranks and found that the retainer on the self-extracting bolt has disappeared entirely. Not really sure how on earth that has happened, whether it’s fallen off when I’ve removed the crank or is lying by the side of a trail somewhere…

Either way, my cranks aren’t coming off until I can replace the bloody thing.

Just went to remove my Dub cranks and found that the retainer on the self-extracting bolt has disappeared entirely.

Nightmare. Weird too, the retainer on my old cranks was so tight I reckon it had been put in by Geoff Capes.`Best of luck, one story ends and another one begins….

It is certainly bizarre. Funnily enough, I have another pair of Dub cranks, complete with retainer, and I even have the correct Park Tool to fit/remove it. So I spent half an hour trying to take off that one, would not budge one millimetre. 🙂

Making the Dub ones with a couple of tiny holes to assist removal/fitting was a masterstroke by SRAM.

Still it’s only the second-worst mechanical nightmare I’ve had today, so all good.