CANT WORK THIS OUT....

[donkeybambam]

I NEED TO TAKE OFF A CHAINRING BUT I CANT GET THE PART OF THE BB OFF THAT HOLDS THE CHAINRING TIGHT. NO SPANNER IS BIG ENOUGH  AND I CANT USE A SCREWDRIVER AND HAMMER TO KNOCK IT AND UNSCREW AS ITS ON TOO TIGHT.

MUNNERS HAD A PLASTIC SPANNER THAT USED TO TAKE THEM OFF BUT HE GOT RID WHEN HE STOPPED BUILDING.

ANYONE HAVE ANY IDEAS WHAT SPANNER TOOL I NEED? IS IT CALLED ANYTHING?

I NEED A SPANNER WITH A 500MM OPENING.

CHEERS ALL......JIM

[Sanmarcopizza]

I'm assuming that you are referring to a 1 piece crank. It's been a while since I have tackled one, but there are spanners out there for the job. Tioga used to include a spanner with their sealed BB kits, take a look in the bottom bracket section here http://www.vert-ego.com/main.htm. I have also have a stepped spanner a bit like this http://cgi.ebay.co.uk/SUPER-B-4-in-1-Headset-Wrench-Spanner_W0QQitemZ270469977738QQcmdZViewItemQQptZUK_Spots_Leisure_Cycling_Tools_RepairKits?hash=item3ef944568a but if your nut measures 50mm, then clearly this won't fit. I'm reasonably certain I have used a very large adjustable spanner in the past, and also a vice, but this depends on the orientation of the flats on the nut and the arms as to whether they will foul the vice. Was also trying to think whether it is threaded the opposite way, but I don't think so. The drive side should be regular so as not to come loose when turning clockwise.

[donkeybambam]

I RECKON THAT SPANNER WILL DO THE JOB MATE.

NICE ONE. 

[Gary72]

I've got one of those here, I had to modify mine to fit by grinding the spanner thinner, Think I made one for monkeybiscuits aswell. Size is 32mm.
Gary

[Gary72]

See here for pics

http://www.radbmx.co.uk/forum/index.php'topic=58607.0

[dannywhiteley]

I use some wide mouth mole grips for that job

[BrianP]

Got access to a bench mounted vise?

Clamp the flats of the nut in the jaws of that, it's how I used to get mine apart.
Also means you can use the crank arms for plenty of leverage.

Brian 

[phantom photon]

As above, I always use mole grips - never failed yet   

[kevin (A.K.A) kai riviere]

500mm    are you sure? that's 20" best part of 2feet. or do you mean 50mm 2" ?

[MartyC]

500mm    are you sure? that's 20" best part of 2feet. or do you mean 50mm 2" ?

Must be for a cruiser 

[donkeybambam]

50mm. Im a plonker!

I brought one of the spanners so hopefully it will work.

cheers lads.

[ED209]

As above, I always use mole grips - never failed yet   

ditto that but with the addition of an old T-Shirt to stop the grips shredding ya nuts