Ax-lightness is a German company that truly specialises in designing and manufacturing in carbon fibre. Their expertise runs along several lines and they are not limited to only bicycle components, but i'd like to concentrate on one item that they make that really grabbed me as a wheel builder. These carbon fibre specialists have given the world of cycling some pretty incredible rims. It causes the mind to enquire, just how light can we safely go with a carbon rim? I am sure that very question was on the mind of the designers at Ax-lightness. Obviously not content with the status quo and possessing a willingness to push the envelope, Ax-lightness went to work. With their ax 25T they have a carbon rim that is an unbelievable 195 grams! If you are not familiar with rim weights let me tell you that this is incredibly light! Only a very experienced wheel builder should embark upon a build with components this light. In comparing various rim weights one can put this into perspective. Because different carbon rims have different shapes, depths and profiles their weights can vary quite a bit. Deep aero rims are obviously going to weigh significantly more than very shallow rims with narrow profiles. The ax 25T is certainly lighter because it has less material being a very shallow rim, but even with those considerations its still feather weight. The specs look like this. The ax 25T is 25mm deep, hence the name, and 22mm wide. The rider weight limit is 100kg and spoke hole counts are either 20 or 24 holes and it's built for conventional rim brakes. Of course these rims would be best suited for your "race day only" wheels. The ax 25T is for tubular tires, so these rims will want to see the absolute best silk tubs that money can buy. Paired with some ultra light hubs you are talking about some of the lightest wheels currently being produced by anybody. But weight and weight alone does not make a great wheel. It has to be strong enough to do the job well and it has to be reliable enough to fill a rider with confidence in a 90 km/hr decent down an alpine pass. Well, Ax-lightness has achieved that goal. Riders have ridden these rims in the most demanding European races including the Tour de France and all went as planned. It's this type of pro level testing and input that separates the good from the great.
I approached ax-lightness about being able to purchase just their rims for some special custom wheel builds. Normally they sell complete wheel sets only that are built in their factory in Germany. After convincing them of my experience as a wheel builder they graciously offered to sell me just the rims. I am very grateful for the opportunity to have access to such special carbon rims! With this opportunity my mind began to consider all the interesting combinations that I could create for some unique ultralight wheels. I'd be happy to share any of those ideas with anyone looking to have a super light pair of wheels built up with one of the lightest rims that I am aware of.