JonB
Zen MBB Master
Hi
I have repaired my backrest with Carbon Fiber reenforcement on the backside. I had to do it because the bottom of the backrest was starting to show fine hairline cracks in the aluminium. The hairline cracks might possibly have gotten there because i may have overtightened the 2 bolts that connects the 2 pieces of aluminium that the seat is made of. And i might have overtightened those during my hunt last year for something that was rattling.
I detached the backrest and removed the drink holders. Then i cleaned the backrest. The carbon fiber adds 70 grams of weight. It is 4 thin layers most places, with an extra layer in the corner and some extra thick "wire" just arround the mounting holes.
I made it out at Leitra.dk, and it cost me 800 dkr / kilo, or about $150 for a kilo. But naturally i only had to pay for 70 gram.
I thought about making a whole seat by making molds of the existing cruzbike seat, but i didnt have any molding material. If i should make a full backrest now, i would just make it by putting carbon fiber on the back "inside" the curve. The reenforcement was made like this.
Making a full carbon backrest might possibly save you 150 grams of weight. The backrest weight is 600 grams. Aluminium weighs 2.7 gram pr. cm3, which gives us a backrest size of 222.222222222222222222. As far as i could find, carbon fiber reenforced epoxy has a weight of aproximately 2 grams pr. cm3. So unless you make it thinner, then a carbon fiber backrest would have a weight of 444.44444444444444444 grams. But since the strength is better, maybe you can make it thinner and thus lighter.
The carbon fiber is probably glued permanently on, but besides this, it is hold in place by the 2 bottom bolts of the drink holders and the 2 bolts that attaches to the other seat pan.
I have repaired my backrest with Carbon Fiber reenforcement on the backside. I had to do it because the bottom of the backrest was starting to show fine hairline cracks in the aluminium. The hairline cracks might possibly have gotten there because i may have overtightened the 2 bolts that connects the 2 pieces of aluminium that the seat is made of. And i might have overtightened those during my hunt last year for something that was rattling.
I detached the backrest and removed the drink holders. Then i cleaned the backrest. The carbon fiber adds 70 grams of weight. It is 4 thin layers most places, with an extra layer in the corner and some extra thick "wire" just arround the mounting holes.
I made it out at Leitra.dk, and it cost me 800 dkr / kilo, or about $150 for a kilo. But naturally i only had to pay for 70 gram.
I thought about making a whole seat by making molds of the existing cruzbike seat, but i didnt have any molding material. If i should make a full backrest now, i would just make it by putting carbon fiber on the back "inside" the curve. The reenforcement was made like this.
Making a full carbon backrest might possibly save you 150 grams of weight. The backrest weight is 600 grams. Aluminium weighs 2.7 gram pr. cm3, which gives us a backrest size of 222.222222222222222222. As far as i could find, carbon fiber reenforced epoxy has a weight of aproximately 2 grams pr. cm3. So unless you make it thinner, then a carbon fiber backrest would have a weight of 444.44444444444444444 grams. But since the strength is better, maybe you can make it thinner and thus lighter.
The carbon fiber is probably glued permanently on, but besides this, it is hold in place by the 2 bottom bolts of the drink holders and the 2 bolts that attaches to the other seat pan.
