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.
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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.
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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 )
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Skibike- 3 months to fully finish |
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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.
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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.
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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.