Skid Plate for the Alta

[Trialsman]

Last time on my MX I ended up making an aluminum skid plate. It was easy to fabricate making a template first from cardboard then transferring the pieces to the aluminum sheet. After TIG welding the pieces togeather I powder coated it and it was ready to install. It worked very well as far protection. The down side was it is noisy when rocks hit it. You never hear that stuff on an ICE bike!!!!

 

[Trialsman]

On my new EXR it comes with a skid plate but it is not as protective as I would like. This time I choose to use my kayak building experience to build a carbon layup plate. The biggest advantage besides weight, strength, conformity is lack of noise when a rock hits it. No more ringing.

After disassembly I hoisted it up from my beam so I could work on the bottom. No worries of leaking oil or gas.


Next I used shrink wrap to encase the motor and battery. The plastic is used as a mold release as the epoxy will not stick to it, if it was polyester resin it would be a sticky mess.


After carefully weighing the resin and hardener, mixing very thoroughly, I layed up the first layer of carbon fiber.

 

[Trialsman]

After 24hrs I removed the carbon which, after trimming will become the surface I layup the rest of the plate. I will be next layering e-glass, then Kevlar, e-glass, and on the outside carbon again. The entire plate will weigh next to nothing and be super strong. This is a similar layup we used to use on kayaks.

 

[Philip]

Awesome! Now all the carbon fiber drooling guys will want your skid plate. Will you be making a dozen?

Also, curious, will you be laying the carbon fiber on the outside or on the outside? Is it a mold or a plug?

 

[snydes]

I would like to see a skid plate design that extends up past the bottom of the fenders rear edge. With my SXS plate all it does is catch and channel mud/debris between the battery and the plate.

 

[Trialsman]

I do not intend to go into any more production but will be happy to supply any information necessary for people wishing to do their own. I was thinking about making a mold and vacuum bagging it for a perfect job, I decided against it. This is the inside and would be considered a plug. Once I do the entire layup, heat cure it, finish sand, and "gel coat" the outside it could be used to make a mold, if more were being produced. I tried to protect the frame, battery, and gear box cover, as well as the linkage. My fender has a mud flap and will rub against the forward lip on the plate. This does a really good job of eliminating mud on the battery/motor. In the end I will be having the carbon on the exterior surfaces with the E glass and Kevlar on the inside (Kevlar fuzzes when abraded).

 

[Redwolf]

I'm interested in seeing how this works out for you, I may have to copy your efforts if it manages to prevent mud and muck from building up on the front of the battery pack.

Mine has about an inch buildup of mud after every ride in the winter when it's wet, and in Western Washington, that means from October to June.

 

[Trialsman]

We get lots of mud here in SW PA. It was common as a woods rider to put that forward lip on the skid plate to reduce mud deposits. Mud adds weight and prevents cooling. Last time out with the MX/EX in the woods it had been raining for a week or more. It was riducously sloppy. When I got back to the truck there was very little mud on or under the battery/motor area. That was with my aluminum skid plate with the lip and my old school mudflap. You can zoom in on the first picture and see the lip is only about an inch long, but enough it contacts the mudflap and seals the mud to the outside.

 

[privateer703]

Now if only there was an easy way to make a rear subframe replacement this way....

 

[Judaslefourbe]

Our testing showed that CF breaks too easily when doing hard enduro/rock garden type riding, but it is awesome for everything else.

 

[Redwolf]

Not all CFRP is created equal... If you increase the ratio of resin to fiber, it becomes more damage tolerant.

 

[Trialsman]

That is also the reason for the blend of carbon, Kevlar, and E-glass. For rock gardens nothing beats aluminum.

 

[Trialsman]

I got a chance to work on the skid plate a little more. It is easier to layup all the layers at once and vacuum bag it, but I didn't have the time / equipment so I must sand in between each layer to assure good adhesion. The second layer was in spots for extra rigidity so I made two ribs running front to back and built up many layers in the four mounting areas later to be drilled and bolted. The Kevlar/carbon weave cloth went next on the inside with a followup K/c layer outside as well. Tomorrow I will add the last carbon layers. After it cures I will trim it to it's finished shape and size then coat the edges with epoxy. The final step will be to put it into the oven for a heat cure then mount it up.

 

[Trialsman]

I just got it off the scale at 17.8 oz. I will post some pictures later tonight or tomorrow. I ended up using a layer of carbon on the outside, then Kevlar, next e-glass, then carbon, and finally Kevlar on the inside. It has a lip in front to stop mud collecting on the battery, sides to protect the battery and gear case, and has a tail to protect the linkage. All in all fairly smooth and flat for sliding over logs. The aluminum one I made for the MX worked well but was just loud with stone hits.

 

[Trialsman]

I got busy with packaging AltaVaults and forgot to post the finished pictures. I have it mounted with M8 x 25 countersunk bolts. Today the SS ones arrive and i will replace the mild steel ones. it really hugs the bike tight and offers a lot of protection. Not great pictures as it picks up lots of reflections from the high gloss.

 

[Redwolf]

Looks very nice, be sure to post a performance report to let us know how it holds up to use.

 

[Trialsman]

Will do ! I am after the slippery, log crossing nature of plastic with a little rock crunching capabilty of aluminum, without the noise. I was able to deflect the tail that covers the linkage. This shows me the addition of the Kevlar took away some of the inherant brittleness of the carbon. It should be a strong yet resilient layup.