A Better, More Thorough Technical Explanation of 3T’s Disc Cyclocross Fork Design
In our never ending quest to get answers and quell your (and our) insatiable appetite for cycling tech, armchair speculation and road/trail side discussions, we reached out to 3T a little more.
After reading it, we got to thinking. Many of the comments on the previous two posts (first look / followup #1) do voice legitimate concerns, but from our experience, ‘cross doesn’t typically involve a lot of things brushing up against the legs of a fork like it would in mountain biking (brush, rocks, etc.), and so we came up with the professional rendering above that offers another reason why the cable placement is OK on the outside: In what scenario will the side of the fork ever directly impact the ground? If you’re falling directly on a raised surface like a barricade, you’ve probably got bigger problems. The lower edge of the fork has no cable on it, and by the time the cable meets the caliper it’s no more exposed than those on a mountain bike. Anywhoo, just food for thought.
Here’s the explanation of the design of their forthcoming Luteus disc brake specific cyclocross fork, directly from their technical director Richard McAinsh:
When we saw the UCI rule change allowing discs for cyclocross we were already starting to scheme a composite MTB fork. After consulting with a few CX and MTB riders, (we sponsor the MIG Team for example), it was clear from the start that this, (an MTB style solution) would not be the answer for CX. The road bike geometry of the CX bike does not allow us the luxury of the massive axle to crown lengths possible with an MTB frame. Tire clearance under the crown is much tighter. Current CX forks with cantilever brakes outside the wheel envelope do not encroach on the tire clearance under the crown. A cable or hydraulic hose coming up the fork leg would be difficult to accommodate and the decision to take it up the outside of the leg was taken pretty early on. We wanted to keep the underside of the crown as clean as possible and not provide any trigger, or key, for mud to start collecting and to cling onto, if the hose or cable was inside the leg it would end up encased in mud being dragged around by the wheel or grabbed by hands trying to clear the mud out. We figured on a CX bike it would be way more vulnerable on the inside than on the outside to be honest.
As for damaging the hose or cable if the bike falls it’s a possibility but actually very remote. There are cables or hoses external all over the frame and if there’s a shunt there’s nothing to legislate which part might take an impact. A hydraulic hose is pretty robust as you’ll know if you’ve ever tried to cut one to length. The fork leg is composite, if you lay the hose against the fork leg and try and bash a hole in it with a rock I think you’ll find the composite gives up first! It’s just not a good argument for not putting the hose or cable where we have.
As for the appearance we debated long and hard about that and it seems it might be quite a polarising feature. We could have not put anything and shown the fork ‘clean’ but I think the feature itself will eventually prove its worth once riders start to build the first CX bikes to the new regulations. This is the first stab at getting something for the early adopters to try; I am pretty sure there will be lots of development going forward.
As for the tie wraps I think there will be more issues with the disc on that side in terms of handling and carrying the bike, I think most riders will trim the ends and tuck them around the hose so as not to offer a sharp edge anyway. They also mean there is nothing external to the fork, no hooks, or riveted clips that could catch and break off allowing the hose to come unattached.
The good news is, our enthusiasm on the matter has us on the list for one of these forks to test out when they become available in mid-spring! One thing we’re curious about is how easy it’ll be to trim/hide the zip tie ends, per his last paragraph.
Personally, I’m (Tyler…can’t speak for the other contributors) more concerned about whether frame manufacturers are going to build disc cyclocross frames with 130mm (road) or 135mm (MTB) rear hub spacing. My vote is for 135 as there are a million disc hubs already ready to go into action, making one less major component that needs to be rejiggered to take your ‘cross bike into the future.