Stack bolts

[Che]

On the basis that good enough just won't do, I was recently struck by the necessity of getting my chainrings perfectly centred, au Sheldon; however upon taking an allen wrench to one of the stack bolts, I found that the entire bolt (or nut and bot, or both sides or the whole thing ... you know what I mean) sought to turn in concert, neither tightening nor loosening. An examination revealed that while the recessed female part had a slot that looked like it would take a screwdriver, the male part of the bolt went far enough through this to preclude inserting same.

So the eventual question: how do you remove a stack bolt when both sides of it seek to rotate together?

Ta
Che.

[MSeries]

Get a chainring bolt spanner

[kyuss]

Get one of these.

[andygates]

That about covers it.  They're cheap and cheerful and any good bike shop has 'em. 

Improvisations with big screwdrivers, etc, often lead to Nutty levels of slipping near huge pointy assemblies of teeth...

[rogerzilla]

Also useful for undoing Brompton front castor screws, if you use the other end and an adjustable spanner for leverage!

[Che]

Aha. Many thanks all.

Indeed were I to manage to put the chainwheel teeth into my knuckles, it wouldn't be the first itme. Got a pretty little pointed-shaped scar on one finger from tightening pedals.

[Che]

Che now owns a chainring spanner.

[bobajobrob]

I use a table knife, the non-blade edge

[Greenbank]

I got a T shaped one from somewhere. Much easier to use than the screwdriver or spanner types.

[hubner]

I do have this tool, but most of the time I don't need it. When I'm fitting a chainring, I put the bolt into the back and hold in place with a finger, then screw the top bit on. As it gets tighter, the 2 parts will pull together and I do the final tightening with just the allen key, no spinning and no chainring tool needed. Same for removal.

But of course, when you do need it, it's very useful  

Oh and that "centre the ring" thing doesn't work, at least not with good quality parts, which should fit together exactly, with no slop.

[Che]

Oh. Boo. I think the Primato chainset constitutes quality in that respect.

I'll have it apart anyway, for the heck of it

[Greenbank]

Oh. Boo. I think the Primato chainset constitutes quality in that respect.

I've never had a problem with either of my Primato chainsets and I'm not that kind to my bike bits.

[Che]

I reckon they're fine. I was trying to be ridiculously over-perfectionist. Thanks.

[Blah]

I got a T shaped one from somewhere. Much easier to use than the screwdriver or spanner types.

One like this? Got one with my last order cos the one I have linked to by Kyuss is really not that clever a design.