Folding 29er Mountain Bike
I have pretty much always taken a bike with me wherever I have travelled – for the past nine years that has mostly been my Bike Friday, as having a bike that can be packed in a regular suitcase in five minutes but ride like a full size bike when assembled is very handy – and no airline fees is nice! The 20″ wheels are great for the road, but for mountain biking you really need big wheels. And with my preference for riding a fully rigid bike, 29″ wheels make good sense. So the goal with this project was to have a regular bike that could pack into an airline checkable case – I acquired one of the 26x26x10 S&S cases which just meets the 62 linear inch rule and just takes a 700C wheel – the 29er tires have to be completely deflated to fit. Whilst in the design stage I decided on a second goal of having the bike fold – there are often times when it would be nice to have a mountain bike that is easy to throw in a trunk or store in a closet.
The resulting bike accomplishes both these goals in a fairly unobtrusive way, whilst having clearance for 2.4″ tires and maintaining a supershort chainstay length of 425mm (16.7″). Adjustable, modular dropouts allow for any sort of setup – right now I have it as a singlespeed, but there are cable stops for a rear derailleur on the frame. To fold the bike, both wheels are removed, then the two quick releases at the bottom bracket are released to allow the rear end to pivot around the BB once the upper quick release is undone. Pulling the seatpost will make the resulting package smaller.
Packing in the case requires several additional disassembly steps. The rear triangle has a removable chainstay bridge, which allows the rear triangle to be separated from the front half of the frame. The cranks must also be pulled, along with the bar, stem, fork and seatpost. Then the pieces all pack together into the case (with the big tires, this meant removing the front tire for ease of packing).
Weight as shown with the fairly heavy Salsa fork, mechanical disc brakes and the BIG tires is 21lbs.