Wayne's New D.I.Y. Skibike

Posted: Sunday, 17 March 2013 by Waynemarlow in Labels: ,

If you want to talk the talk then I’m a great believer that you then have to walk the walk. On many an occasion I have questioned the validity of some of the spurious ski bike builds I have seen and the direction we as a group have gone in the way we are building and designing ski bikes.

So at some stage I thought I would take on the whole process of design, build and then trial all those ideas of mine. It may seem a little daunting but having now been through this process it was actually quite a lot of labour intensive fun with a great result, well at least I think so.

Skibike frame had to fit into a double ski bag

So some criteria first. The bike frame had to fit into a double ski bag for easy air travel, seem like a bike to stand on, fit the lifts, handle my lardy frames weight, be less than 10 kilos all up including the skis and be better than the original bike I had built 2 years ago which seemed to be pretty good out of the original design build.

Scratch built - 100+ hours of time
OK measure up the original bike and convert it to a CAD drawing and then modify the few points that I thought were wasteful, wrong, overweight or simply not needed. So first thing to go was the rear suspension, as a non jumper, XCountry type and I freestyle all of the time, my own suspension ( legs ) would do. Change the rear ski mount to get as low a COG of the pivot as possible ( to get best edge control ), increase the head angle to about 72 degrees to reduce any head shake along flat paths, what else, be a minimalist to reduce the weight.

So then create a full size CAD drawing, place it on some foam, cover with a mix of carbon and glass in all the right places, fill prime and paint. What more could one do. Sounds easy but I bet there was 100 – 150 hours of time involved. Now on one’s winter evenings what more has one to do, Ok quite a lot and it did take me about 3 months to fully finish the bike and a further 10 hours or so to repair and resolve the couple of issues I had from the first day I rode it ( the front seat post bolt pulled out of the frame which then broke the rear mount, yes the sound of breaking carbon fibre is not a good sound )

Skibike- 3 months to fully finish
Super light - just 7.2 kilos

Was it all worth it, mmmm yes and no. Great fun and a great bike to ride but definitely not a bike to learn on, its like a light weight race horse that just takes no prisoners, the slightest bit of weight on either peg and it will head in that direction, get the process of upweighting and changing the peg pressure wrong and it simply picks up speed in comparison to the fully suspended bike I had been used to which is a very forgiving bike. On the plus it is very very light, just 7.2 kilos including the skis ( my Vokll AC30 skis are just over 7 kilos ), it has now survived a pretty damaging ( constant ice and lumpy snow ) of a hard week of testing and nothing has broken, plus it is drop dead gorgeous to look at and if I thought the last bike caused a few heads to turn, then this one really does get people asking where they can get one from. 
Overwhelmingly fast

Would I change anything, on the first day I rode with a suspension seat post ( gives about 50mm of travel ) to give a little comfort on the drag lifts and when just cruising about, on the week of testing I had a normal seat post and man was that a solid ride up lifts, ouch but it did make me freestyle all of the time. I do like the way the lowered COG of the pivot on the rear ski works and I really do like the low weight to and from the lifts and going up the lifts. But I cannot recommend the directness and positive response you get from having no rear suspension, for the learner it’s just overwhelmingly fast and could easily put people off the sport. At my stage of ski biking it took a little to relearn but once I had found how little input was needed to turn and how best to use the bike, it was a sheer joy. I would liken it in skiing terms to the difference between a learners ski and a full on slalom racing ski which a beginner would not be able to use well.
  Great skibike to ride but not to learn on

So should I make the plans and build schedule available, if enough of you convince Mark then perhaps I can put the time in to document the build and make those available. With good resources available now on the web on how to build composite ( carbon and glass ) structures plus composite materials being widely available, it is doable. 

Next Autumn I'm going to modify the plans and build a rear suspendered version to just see what the real merits / differences are of the rear suspension issue, just to compare. Looking foward to next autumn then, but now its late March and its time to pack up the winter toys and get back to playing with racing cats.