Maximum Fork Lengths & Dual Crown Forks
Axle to crown is the measurement between the centre of the fork’s axle up to the flat surface on the crown where the lower headset race sits. As a fork’s travel increases, so does its axle to crown measurement.
Each RAAW bike is designed around a certain axle to crown fork. This dimension is one of the fundamental measurements in the geometry of a bike, so needs to be clearly defined right from the beginning of development.
You can think of the axle to crown measurement as a lever into the frame, from the front wheel to the head tube. If we put a longer travel fork onto a bike then we increase that lever length, multiplying the force into the frame. If we go really too long with this lever for a certain bike, then it’s possible to run into some strength problems.
Changing the fork length also changes the geometry of a bike. As a fork gets longer, the bike’s head angle and seat tube angle slackens, the bottom bracket and bars raise up and the reach shortens.
On the Madonna and Jibb it’s more than OK to run a 10mm longer travel fork than stock, as the geometry change isn’t that drastic. But going too far can have a detrimental effect on the geometry and the way the bike will fit and handle.
Imagine running a 180mm travel fork on an XC bike. It would ruin the geometry, be a huge miss-match with what the rest of the bike is intended for and potentially lead to some problems in the strength of the frame. All around not good.
It’s necessary then to state a maximum fork length for the bikes to ensure that the geometry stays as close to how we designed it as possible, and that the lever into the frame remains at a good length. Exceeding this recommendation will void the warranty.
|Madonna V1||586 mm|
|Madonna V2 & V2.2||596 mm|
Dual crown forks are generally found on DH bikes and use a crown above and below the head tube for added stiffness and strength.
However, having a crown above and below the headtube means that the stress distribution in the frame is drastically changed when compared to a single crown fork. There’s simply another crown adding the forces from riding into the frame.
For that reason, we don’t recommend running a dual crown fork on the Madonna and Jibb frames, as it will void the warranty.