Rock Solid Hobie crank arm axles

When fungunnin had his "rock solid" Hobie crank arms on sale over the holidays, I couldn't resist buying a pair. I probably won't use them since I've been experimenting with making my own, but I really wanted to take a look at them.

IMHO, they are very nicely done---excellent and highly professional workmanship. But, there is one issue that I don't think has been mentioned in the previous threads (although I haven't read thru all of the posts, so I might have missed it).

The axle that is provided is not 316 stainless. Instead, it is apparently 416 stainless, which is not considered marine grade. The first picture shows the "rock solid" axle with a magnet sticking to it. The second photo shows the standard Hobie axle, and a magnet will not stick. A magnet will not stick to 316 stainless, but will stick to 416 alloy.

So, if you're using the "rock solid" with the provided axles, you'll probably want to keep an eye out for any early signs of corrosion.

Not to call you out here but you do know there are magnetic and non magnet stainless of the same grade. A magnet test doesn't really show you the grade as far as I understand, I don't have a degree in metallurgy but I googled it... Not sure how you concluded it is 416 ss but it can be just as resistant to corrosion yet still retaining its strength.

Not to call you out here but you do know there are magnetic and non magnet stainless of the same grade. A magnet test doesn't really show you the grade as far as I understand, I don't have a degree in metallurgy but I googled it... Not sure how you concluded it is 416 ss but it can be just as resistant to corrosion yet still retaining its strength.

If the magnet sticks there are ferrous materials in it.  Corrosion will occur

17-4 is magnetic and corrosion resistant

Not to call you out here but you do know there are magnetic and non magnet stainless of the same grade. A magnet test doesn't really show you the grade as far as I understand, I don't have a degree in metallurgy but I googled it... Not sure how you concluded it is 416 ss but it can be just as resistant to corrosion yet still retaining its strength.

When I compared the Hobie axle and the "rock solid" axle, it seemed pretty obvious that they were not the same alloy. So, I asked fungunnin what alloy was used for the axle, and he replied that it was 416. I then asked something like, "Are you sure? That's not considered marine grade." He said he'd check and get back to me, but I never heard from him. I assume he just forgot about it and I didn't press.

IMHO, the "rock solid" crank arms are fabulous and well worth the money, and this is a fairly minor issue. But probably something to be aware of...

With proper care & maintenance, I highly doubt the differences in stainless/aluminum types, as far as corrosion is concerned, will become an issue for a kayaker.  These, generally, aren't left in the water for days/weeks at a time & most of us maintain them with freshwater rinse/lube so corrosion, in my mind, is sort of a null point unless you just don't want to deal with any routine maint.

Fungunnin's drive arm assemblies are unique in that one has the option of threaded bike pedals or a threaded rod that accepts stock Hobie pedals. That threaded rod is stronger than a stock Hobie press fit rod and will not wear out. Hobie no longer supplies the V1 solid threaded arms so Fungunning is the only game in town unless you make your own from marine 3/4 solid stock.