Daniel writes that the noseboom and the rear wheel stay have half the weight of his R1.
The shell of the bottom bracket weighs 21g. Some regions of the rear part of te R4 were not done in honeycomb this time but still as sandwich as they will carry the wheel holds. Daniel is a bit worried about the seat which is a little too hard, he writes. It is a supporting part of the construction and weighs 500g. 50-70g less would be sufficient as well, he writes.The weight he saves with the new steering tie rods is more than 300g.
The entire body with rear compartment, bridge, bearing for the idler roller and the steering tie rods weighs about 7700g. Daniel thinks that 7kg are the limit.
Including seat, mast (noseboom) and rear wheel fixing it makes less than 9kg and makes Daniel heart laugh;-) With all parts assembled he will end at 18kg for the entire vehicle.
It is not a cheap fun to build like this. The materials only for the selfmade parts cost around 1800€
Daniel states explicitely that although he built it light, he did not do it careless.
See the photos: