Shock mount adapter drawing

[elPedro666]

Hi all, I'm guessing this may be on here a dozen times already, but in my desire to be a helpful noob I've got a drawing of an adapter to run a standard rear shock (think Fox were recommended).

All I need now is to try and get it posted...

Just to cover my ass a bit (tragic it feels necessary), use it at your own risk!

Hope it helps someone out 

[elPedro666]

[fyrstormer]

Two problems with your design:

1. The shock eyelet is only supported on one side, which will put an unbalanced shear load on the bolt passing through the eyelet. (i.e., it will try to bend the bolt, which is a really good way to make a bolt fail.)

2. The inset on the adaptor where the shock eyelet fits into place would either have to be an exact match for the shape of the eyelet, to compensate for problem #1, which would restrict which shocks could be used; or it would have to be oversized to allow compatibility with all shocks, which would offer no structural support to the shock/adapter interface.

The best design I've seen has supports on both sides of the eyelet hole, so the shear load on the bolt is balanced, and the central cutout is oversized to allow usage with all shocks on the market. The fact that this design can still pivot around the eyelet is not a problem, because the strut is more than strong enough to resist the shock's tendency to bend sideways. The ability of the lower eyelet to pivot sideways also relieves shear-loading on the bushings inside the shock, which were a known point of weakness in the original strut-mounted-shock design.

[elPedro666]

This is one that's been passed on to me so I'm just passing it on again, but I think the two main advantages are that it's simple to machine and has been in use on a bike successfully for years.  Doesn't necessarily make it the best solution I agree, but if it's doable, cheap an it works it may be of use to someone

[fyrstormer]

For something like a shock mount, safety is more important than affordability. If the adaptor breaks, you'll trash your frame and probably crash into something sharp and pointy.

[jimbob]

My 857 has a rear shock adapter, you're welcome to buy it, it comes with a free frame attached!   

seriously though, the one I have supports the lower shock mounting point on 3 sides and is over-engineered, but better that than a trip to the ER....

I'm sure the drawings for it were posted on here at some point??

[Spokes]

Yep the drawings are 4 posts above.

Chris

[jimbob]

Yep the drawings are 4 posts above.

Chris

Oh yeah!   

[Spokes]

Well ive just bought the same adapter as in the drawing off Jimbob's 857, so i'll road test it as hard as I can and report back any issues. My 857 has a Risse Astro 5 on it at the moment so it will be interresting to see how they compare being as Risse are the only real alternative.

Chris

[al079]

Does anybody have a source for these adapters?  I just started riding again and I would like to be able to replace the NR-4 with a lockout type shock.  I have been told the bike continually bobs up and down and I would like to be able to lockout when on pavement/steep off-road climbs.

[Spokes]

No these adapters are very much limited run items by whoever is making them at the time. You can use the drawing above to have one made though.

Chris