Advice needed. How tight to go with the allen bolt that secures the crank arm in place?

[Cyclopathic]

I'm putting the crank arm back on to the bottom bracket and I have never done this on this type of set up before. It's a carrera mountain bike and the crank is secred with an allen bolt straight into the end of it.
Should I tighten it up absolutely as much as I can so that it is pulled onto the taper as much as it possibly can be or does this run the risk of putting too much pressure on the bolt and dethreading either it or the axle.
Thanks in advance for any ideas .

 

[gbb]

If its a standard square taper with just that bolt to secure the crank...in theory it is possible to snap the bolt if its old or weak, but generally, do it up as tight as you can, and that means really quite tight otherwise you'll risk it coming loose or allowing the crank to move on the taper.
You can pre-empt problems by inspecting the bolt, do the threads look good, are any showing signs of wear, stripping or stretching.
Ultimately, it want's to be done up tight. Ive never had problems and i use a socket and ratchet which probably exerts more force than a spanner.

 

[Cyclopathic]

If its a standard square taper with just that bolt to secure the crank...in theory it is possible to snap the bolt if its old or weak, but generally, do it up as tight as you can, and that means really quite tight otherwise you'll risk it coming loose or allowing the crank to move on the taper.
You can pre-empt problems by inspecting the bolt, do the threads look good, are any showing signs of wear, stripping or stretching.
Ultimately, it want's to be done up tight. Ive never had problems and i use a socket and ratchet which probably exerts more force than a spanner.

I should be ok then as I am using a new bolt. I do think though that this is a weak design that seems to have some obvious inherent pitfals.

 

[TheDoctor]

It was the standard for a good number of decades without any real issues.
HT2 is a lot less of a faff though.

 

[mac1]

I can recall Bicycle Tutor saying about 40 newtons using a torque wrench if you have one.

 

[gwhite]

Make sure and grease the bolt as this allows the correct torque to be reached.

 

[ASC1951]

If you're just using the allen key i.e. without a bar on the end of it, I doubt if you'll be able to get enough force on it to strip the threads.

Some people seem to insist on doing up pedals and cranks stupidly tight, especially with a 16" pedal spanner. There's no need. I've never had a torque wrench, but 'snug plus a bit' works for me.

 

[mattsccm]

Allen keys that size seem to be about 9" long. Swing until it hurts. You won't do any dmage and its plenty tough enough.