How to figure out if my suspension forks are steel

[mojones]

I've got a 36V front hub motor kit on the way and I'd like to fit it to a bike that has suspension forks. I keep reading that only steel forks are safe for front hub motors - how do I find out if mine are? I bought the forks from here :

http://www.chainreactioncycles.com/Models.aspx?ModelID=7697

presumably it's the sliders (i.e. where the dropouts are) that need to be steel. In a quick with a pair of digital callipers test last night I found that I could quite easily spread the legs to 110mm from their normal 100mm width - is this flexibility an indicator that the forks are steel?

 

[barabranch]

try using a magnet. i have front hub 5303 on suspension alum fork but had to make torq arms to work with 20mm thru axle type fork. heres a earlier post http://endless-sphere.com/forums/viewtopic.php?f=2&t=3784

 

[mojones]

OK, now I feel really stupid - will try a magnet when I get home.

 

[dogman dan]

Steel will have smaller beads where the dropouts are welded on. If no welds, the fork will look like a tube pinched flat. If it has fancy shapes, its cast aluminum. Sometimes you see a bike and don't have a magnet handy.