Instructables
Picture of How to Create a Downhill Skibike
121.jpg
123.jpg
Living in a frigid northern climate enables its residents to enjoy snow for many months during the winter. For avid mountain bikers, that can hinder the amount of riding time on fast, packed dirt trails. Not wanting to be slowed by snow in the winter months, I set out to combine my passion for mountain biking with the speed of downhill skiing. This mash-up of sports yields an incredibly fun, challenging and extreme sport of its own: Skibiking.

This instructable documents my journey using the engineering process as I designed, built and rode my own version of a skibike. Several skibike instructables already exist for quick and easy skibiking fun. However, if you want to build a serious snow shredding machine, you will want to follow this Instructable as I describe the crucial aspects of skibike design and the implications of various design choices.

Below are the steps of the engineering process that I employed.

• Define the problem or need
• Research existing intellectual property and history
• Conceptualize & brainstorm
• Establish design requirements
• Product design
• Production planning and tool design
• Production/Manufacturing
• Test & Analyze
• Repeat (coming soon!)
 
Remove these adsRemove these ads by Signing Up

Step 1: Research

There was no advantage for me to "reinvent the wheel" so instead of trying to develop everything on my own, I first conducted research on the internet to find out 1) what was already developed, 2) what designs or characteristics I wanted to utilize, and 3) designs or characteristics I wanted to avoid. Another useful research trick is to understand how the sport has evolved over the years. That helps to confirm a potential design isn't outdated or purposefully avoided by the industry.

Despite their lack of mainstream use (and possibly even awareness), Skibikes have been around in various forms since the 1960's! And just as your standard bicycle or set of skis, these designs have significantly improved over the years. In the following steps, I’ll describe how I used some of the information I gathered to influence the design of my own skibike.

Don't you mean the...
*removes sunglasses*

B-icicle!

Ravirar5 months ago

How does pedaling increase speed? There is no wheel system, so I don't see why you need pedals or gears. Cool ible though! :)

Schorte Ravirar5 months ago

As it will not be possible to temporarily remove one's lower limbs while ski-biking, the use of pedals as an appendage rest point seems most advisable.

Ravirar Schorte5 months ago
Yes, you are right. Might I suggest that you add a gear system like a real bike and connect it to a spoked or chained wheel for good traction so that you can pedal uphill?
B4SEC4MP (author)  Ravirar5 months ago

Nice idea. You should make one! I did consider leaving the rear wheel on the bike, but thought I'd be able to go faster downhill with a ski in the rear instead!

Ravirar B4SEC4MP5 months ago

:)

Sadly I don't have the tools/materials to build one and it is spring where I am.

:(

criggie Schorte5 months ago

Pull out the bottom bearing and put a straight pipe through... that way theres fewer moving bits, no bearings to get wet, and the feet are at equal height.

ejay1 Ravirar5 months ago

It doesn't increase speed, the pedals are there to rest your feet on.

Ravirar ejay15 months ago

oh

Marsh5 months ago

Since you don't need the crank, you can remove one side and make it so the pedals are aligned with each other (assuming its a three piece crank). If you tighten the bearings enough, it will lock the crank into place.
A brake would be a real great addition.

B4SEC4MP (author)  Marsh5 months ago

That is a good idea and I've thought about lining the (3 piece, square tapered) crank arms up in the same direction, but the crank arms I was using were 170mm long so I felt they would be a little too long and tend to "swing" while riding. The bottom bracket I was using was a fully sealed unit so there was no way (that I saw) to tighten it and reduce the ease of rotation. That would have been nice to be able to do that. What do you mean by a brake?

si Marsh5 months ago

Nice idea, but I'm assuming he'd like to use the bike (including bottom bracket and cranks) again in Summer, but I guess if you had some old cranks and bb lying around you could swap them over.

Marsh si5 months ago
Actually, if its a three piece crank, you can just undo it all and use it again anyway.
si Marsh5 months ago

So long as the bearings weren't trashed...

But to be honest, given the environment it's being used in, chances are you'd want to use a different bottom bracket for riding it on wheels.

Quester555 months ago

Such a Great Idea, So tell me, Have you thought to mount the Forks directly to the Skis? Or Installing Mini-Shocks to the Forks & then to the Skis?

Your Idea , Like I said is great, I'm just more concerned for your Safety, As your Center of Gravity , Will be off, due to the High boards(Stilts) your using.

B4SEC4MP (author)  Quester555 months ago

I did consider mounting the forks and dropouts directly to the skis, but decided to keep the axle height similar to (but slightly lower than) a typical 26 inch wheeled mountain bike to preserve the "bicycle" feel of the ride. The center of gravity is still lower to the ground than a typical mountain bike (and therefore very stable) because of the lower axle heights. Mounting the skis closer to the forks and dropouts would also severely reduce the clearance of the foot pegs and would be much more likely to hit the snow and cause a crash. Thanks!

nightmare_man5 months ago
Nice design, but you might consider using something other then wood, or at least make sure it's prepared properly, for the ski frames. Regular lumber likes to suck up water, which will warp the wood or simply make it weak. Also the changes in temp if/when you bring the bike in to a warm place for storage will make this worse. Wouldn't want any catastrophic failures while riding. Take extra care of the ends of the 2x4s and any where it's penetrated with nails/screws.
B4SEC4MP (author)  nightmare_man5 months ago

You bring up a good point. I did end up painting the wooden mounting brackets partly for the reason you suggest and partly for the aesthetics.

+1

User15 months ago

Dang, I thought I was going to see a video of this bike in action :-(

B4SEC4MP (author)  User15 months ago

I just updated the Instructable with three videos! They're short in length, but I think give a good sense as to how the skibike handles.