If you have followed the news from the cycling world today, you may have heard about the "novel" convertible bike concept by a small German startup - 8bar Bikes. I suppose, the Mitte is their answer to this ancient question - if you could have only one bicycle, what would it be?
Many people would want something that is fast on roads but capable of off-road riding at the same time. There are already bicycles like these. Many adventure, gravel or cyclocross bikes fit pretty well into this category. But apparently, 8bar wasn't satisfied and they came up with their own solution. The Mitte is a road bike that "can change into a cyclocross bike within 15 minutes". This is done by swapping out the fork and tires. Also, the Mitte can become a touring rig with racks and fenders added.
Watching the video on their Kickstarter page today, I realized how close and how far at the same time this concept is from the idea I had about 2 years ago. I was trying to answer myself this one question - what would be my one-bike-to-rule-them-all solution?
The first problem I have with the Mitte is that swapping out the fork is not something trivial and not something I would want to do every time I go for a ride in different conditions. Then comes the problem of gearing. This bicycle is equipped with a standard road crankset and a wide-ish cassette - both good for the road, but not very much suitable for off-road riding. Overall, the Mitte is a compromise and feels a bit like a solution in search of a problem.
My take was a bit different. Instead of changing forks and altering the geometry, I would just leave everything pretty much the same, on or off road. That is, a road bike with a 72-71.5deg head angle and ~440mm chainstays may not the be raciest and most agile one, but it doesn't mean it wouldn't roll comfortably on road. Quite the opposite, in fact.
The trick to satisfy both uses is simply in swapping wheels - something that can be done in one minute and without tools. First, I thought that sliding dropouts (like those on the Mitte) are the answer, otherwise how else would you fit 700C-sized wheels with either road 28mm tires or off-road capable 1.95" ones? But then I realized one simple fact:
The outside wheel diameter for a 700C wheel with a 32mm tire is the same as a 650B wheel with a 2.0" tire.
This makes things simple. Just build a frame with enough clearance to fit 650B wheels with ~2.0" wide tires and a 135mm rear spacing (for hub compatibility), then swap out the wheels to ones with narrower tires if you want something faster on pavement. No need to fiddle with the fork.
Next, add a wide-range gearing such as a 46-30T crankset and 11-32T cassette and this way you could have a bicycle that does it all - it's still pretty fast on road and much more capable off-road than any cyclocross bike.
Thinking more about it I started to wonder why such solutions aren't advertised more? I quickly realized that this is not going to happen. Bicycle manufacturers don't want you to buy one bike that can be used anywhere. The want you to buy 2 or more "specialized" ones: a road bike, cross bike, gravel bike, a touring rig - who knows what else? I guess the only way to get a bike tailored to the ways you want it to ride is to have it custom built.
On the other hand, I already have one. It isn't as fast as those aero carbon machines and not nearly as off-road capable as a dedicated mountain bike, but it can handle various conditions surprisingly easily.
My road bike...
... and a "mountain bike". Same bike, slightly different package.