Bike is a STUMPJUMPER FSR COMP EVO 29 (2015 model, only a few months old), and crankset is the stock ‘Custom’ SRAM S-1250’. I want to fit some new cranks, but can’t get the old ones to budge. There is only one accessible bolt (which I believe is self extracting) – a 8mm hex on the drive side, and it will not move. When I have had this issue on other bikes, I was either being a doofus and undoing the wrong way (i.e. clockwise), or (more commonly) I need to put an old seatpost or similar over the Allen key to get some extra leverage (has always worked for me in the past). There is an arrow on the old cranks indicating clockwise to tighten, so I’m pretty sure I’m not going the wrong way – but I’ve never had cranks that required so much force to undo…to the extent I was concerned something was going to snap, and it still would not budge. Any ideas, other than looking for a longer lever? It’s a ball ache to visit a shop, nothing local. Note that the shop had put the pedals on and they were also very tight….not sure if the shop would also have installed the cranks, or if done at factory.

Anyone suggesting I MTFU will get the reply they deserve!

Bigger Lever.

These ones can get done up a little tight, if your feeling squeamish then drop straight back to where you got it from and ask then to take it off for you. Shouldn’t charge you for that.

don’t use an Allen key. Use a ratchet and 8mm allen key socket.

Soak area with a penetrating oil leave for a good few hours have another go might be worth looking on spesh website just to make sure your not missing something as my fellow Engineers always say preparation prevents p##s poor performance 😀

don’t use an Allen key. Use a ratchet breaker bar and 8mm allen key socket.

Boiling water on the interface?

Does the boiling water trick work?

Plus gas / penetration fluid is your friend, let it soak in, then the trick is you need to get it evaporating, so plenty of boiling water and then a decent lever to try and get it away. You might need to Repeat it but it will work

Any advice on which ‘Plus gas / penetration fluid’, and where to get it?

plusgas is the brand name. You can get it from places like Euro Car Parts or any other motor factors, I would imagine.

Screwfix do their own version called No Nonsense Penetrating Oil and Halfords will have something similar.
I would have thought that places like Wilkinson/B&Q would also do something appropriate.

Plusgas itself is very good, though not that easy to find in shops. I saw a test in I think PPC mag that found GT85 is almost as good though. Not totally sure I believe that, but they do know their rusty shit cars.

Already tried GT85, but will keep trying

I would go easy with the large breaker bar and 8mm bit, there is a good chance you will round or break the bolt.

As above, try plusgas or similar, keep soaking it for 24 or even 48 hours. Kettle is a good shout and give the bit a good hard knock with a hammer (straight on rather than in the direction you are trying to turn it). Last one is try tightening it a bit before loosening, repeat as many times as you can.

Good luck

Northwind – Member

Plusgas itself is very good, though not that easy to find in shops. I saw a test in I think PPC mag that found GT85 is almost as good though. Not totally sure I believe that, but they do know their rusty shit cars.

I spent a long time trying to remove the wiper arms from my car, as the mechanism was seizing. They would not release from the taper, despite soaking in GT85 repeatedly over several days, applying hot water, whacking with a rubber mallet……
Went & bought some plusgas – applied it and made a cup of tea. Tried to remove, but didn’t expect it to have worked in such a short time & it had. They came off straight away – although how much of this is to do with the prior efforts I cannot be sure.

It feels different if you get it on your hands – thinner than GT85.

That bolt can be a pain to remove. Never had one round or snap despite Useing a long bar,
But if the bikes that new just drop back to the shop and get them to pop it off

Thanks for all the suggestions. Will try some more tonight/over the weekend. May have to resort to taking it back to shop, but want to avoid that if I can as it’s not really local (before anyone asks…there are no local bike shops).

long bar did the job eventually, with a bit of perseverance.