What is the fastest tire for your Brompton?
- Posted on
- By Chuck Ankeny
Comprehensive independent analysis of bicycle tires reveals some surprising insights and conclusions.
With the 2018 Brompton World Championships just a week away, I'm starting to get my Brompton race ready. For the US Championships in Monterey two years ago I rode my stock P6L-X with SON hub dynamo and heavy Schwalbe Marathon Plus tires. It did fine but I felt like I needed different handlebars for the fast descents - ones where the brakes and shifters were at the same place as my hands!. This past April at the US Championships in Monterey I rode the same bike but with a few modifications. First, I swapped out the handlebars. I used an "M" type stem riser post and put on a pair of flat bars with a 50mm rise to them. The net effect was pretty much the same height as the "S" bar bikes. Then I removed fenders and the complete lighting setup including the front wheel with the SON front hub dynamo. I replaced the front wheel with a custom built wheel using a Phil Wood hub with ceramic bearings and a Sun Ringle CR18 polished silver rim. I also swapped out the Marathon Plus tires for the Brompton-spec folding bead Schwalbe Kojak tires. The bike looked and felt faster and was a few pounds lighter which is very important in the hilly terrain of the Laguna Seca race course.
So, what did I learn and what do I want to do differently for the upcoming World Championships?
First of all, I learned that the riding position does make a huge difference. With the lower flat bars I was able to get my chest out of the air and achieve a more aerodynamic position.
Secondly, while I can't quantify it, I felt faster without the fenders. I also felt the loss of weight by loosing the lights, dynamo and heavy tires. A pair of Kojak tires weighs 13 oz. A pair of Marathon tires weighs 1 lb 10 oz. A pair of Marathon Plus tires weighs 2 lbs 1 oz. So the pair of Kojak tires are nearly a full pound lighter than the Marathon and well more than a pound lighter than the Marathon Plus. Remember, reducing weight is especially when climbing BUT that is not the whole story. The other huge factor is rolling resistance. One would assume that the Schwalbe Kojak, with its racing slik construction would be the fastest - Science has proven otherwise.
In a comprehensive, independent analysis of a large number of high quality bicycle tires done in the Netherlands by BicycleRollingResistance.com, the Schwalbe Marathon tire was found to be quite a bit more efficient than either the Kojak or the Marathon Plus. In fact, with each tire inflated to the same 90 psi, the Marathon tire required just 18.8 watts to keep the tire rolling at 18mph with a 94 pound load. The Kojak required 20.5 watts (almost 10% more) and the Marathon Plus required 20.9 watts (11% more). So you can see that over flat ground where weight isn't an issue, the fastest tire should the the Schwalbe Marathon. An added bonus is that you get far superior flat protection so flatting during the race is highly unlikely.
So, with the flat course in London, I'm planning to use the Marathon tires.
Yes, the Kojak's do accelerate faster for sure.
Really interesting thoughts - I went from the original Brompton tyres to Marthon pluses and the bike now feels like wading through treacle. Wondering about Kojaks - the other factor i suppose for commuting is the inertia in the tyre with it's weight - conceding that Kojaks have lower speed for given effort but they might just accelerate faster?