How thick should a fork stanchion be

[velomaniac]

I have a crappy set of DNM Comet elastomer forks that weighed a ton but had enough clearance for a 29er wheel. So I ripped the heavy innards out and replaced the stanchions with aluminium alloy round tube with a wall thickness of 1.6mm resulting in rigid much lighter 29er forks with disc brake mounts. The forks clamp together Marzocchi style, I think they're Marzocchi inspired.

Here though is my question though, is 1.6mm wall thickness enough with 6000 series alloy for a mtb or should I go for something thicker like 3mm ? It seems strong enough but I'm no metalurgist and I like my teeth as they are :roll:

 

[Chute55uk]

the wall thickness on my jr t's are probably no more that an mill or so and they take some abuse. there alloy of some kind but no idea what. i would ask a frame builder they should know

 

[02gf74]

interesting question :?: - are the stanchion steel or alloy on the Mr T?

1 mm alloy does not sound particularly strong to me. :?

by the way, stanchions are coated and I'm guessing here coz that is what is done to motorcycle ones, are ground to give a precision surface. I am not convinced sticking in any old tube is going to perform as well, without the coating I would expect the surface to wear pretty rapidly.

My gut feel it they will be similar thickness to the tubing used in the steerer, whcih is certainly more than 1.6 mm for alloy.

 

[Chute55uk]

im guessing they are anodized alloy as they weigh nothing and have that definite alloy feel.

 

[02gf74]

ok, I stand corrected Stanchions: Anodized EASTON aluminum with variable butting

if they are same as these.

 

[velomaniac]

I think I need to emphasise I have converted these forks to rigid as the aluminium round tube that is serving as stanchions occupies all the innards of the forks from the dropouts to the fork crown clamp. Thus the forks dont slid up and down. I am only concerned with how thick this tubing needs to be to be safe for offroading.

 

[coomber]

Ceeway list dimensions if you can decipher them?

http://www.framebuilding.com/Forks.htm

 

[Chute55uk]

ok, I stand corrected Stanchions: Anodized EASTON aluminum with variable butting

if they are same as these.

yep thems the ones

 

[stevet1]

I would have thought it would make a massive difference if you have converted them to rigids as now all the force is acting on the tubing.

 

[velomaniac]

Yep, my thoughts entirely thus I think i'll go cautious and go thicker possibly up to 5mm. Forks will be heavier than now but lighter than original and still cheaper than new purpose built forks. £60 for cheapest suspension adjusted forks is a bit too much for my wallet currently. Thanks for being my sounding board guys