Monday, December 29, 2008

Carbon Kouign Amann (Speculos Evolution 1)

Second day of testing. Geoffroy is much faster than yesterday. I gave up following him with my mountain bike and watched him turn and turn around the block. A smile on his face says it all, the bike is well born.

Geoffroy was the first one to test the bike. He is a front drive beginner but managed to ride without any problem. The front end is lighter and easier to steer and Marc's steel bike as expected. The balance seem good and it feels faster than a VK2 according to the rider. Well the bike weighs about 6.8Kg complete and that could explain the good up-hill speed also.
The frame behaves well on bad road and the back end looks a bit too stiff but it might just be a visual effect from the large seat.

07/02/09 If Batman had a bike, it would certainly look like that: I will now start the paint job and I have a surprise for my friend Black adder. The steering clamping system is not final. The frame feels stiff enough. This bike can be a SUB 7 with a lighter crank. My next bike which will be an evolution of this one should be much lighter. :) 27/01/09 The Shimano bar end shifters have been fitted. The 4th gear was missing so we decided to open it. Well that was a bad idea, it took 5 minute to open it and about 2H to reassemble it. The first spring was tricky to fit. It really looks like a Swiss watch inside. I am not convinced they need that many seal and gasket. Never mine! I also fitted a set of Tecktro levers. They are fitted facing backwards on purpose to keep the cable as long as possible in the handle bar. The crank has been drill at 150mm. The ends will be reduced later. This baby weight a tonne! I just bought a Broken stronglight carbon crank and I will try to reduce it soon. 16-01-09 The seat has been bonded to the frame so as the bottom bracket. I now need to reduce the crank length from 170mm to 150mm. 5th January 2009 The seat and handle bar need ajusting on the frame. The seat will be bonded on the frame to improve the side stiffness of the frame and save a bit of weight. The drawback is that it is impossible to adjust the bottom bracket length. Hope it will be OK.... The stem is now built and taped to the U handle bar. The stem is longer than necessary and will be trimmed to fit the rider's position. The handle bar is now fully covered with carbon. At this stage is weighs about 200g. It really looks like a Batman boomrang. The handle bar is made in a piece of foam and covered with two layers of carbon (300g at 0/90 and 400g at +/-45). The tubes are made over a PVC tube but this is not very accurate as the overlap creates a bump. A female mould would be a better idea to get the 22mm diameter. 29 December 2008 A friend of mine (Gilles) has decided to build a similar bike and he has started by a 3D drawing of the bike and it is a good exemple to show how accurate drawing can help to spot problems. The 'BEAST' is on wheels. I still need to increase the cut-outs in order to make the bike look lighter. I am now waiting for the bearings to arrive for the US and for the seat + handle bar drawings. The bike should be ready in a fortnight and I hope that stiffness will be ok. The front part of the frame has been built in a few hit. A male foam mould has been used to give the basic shape then volume has been added to increase stiffness. This might not be necessary but for the first frame it is safer. The next stage is to build the head tube with a female mould and a bladder. Well this is not easy and the result is 'just' acceptable because the bladder lost pressure. The front of the frame should weigh about 1.2Kg with paint. The rear frame is now complete and weighs 900g so it should be around 1.1Kg after painting. I made a carbon tube 1"1/8 to fit the headset bearings. I tried to keep the frame very narrow (35mm) between the legs because it can be painful if your legs wear on it for a long time. The back of the frame is built with my usaul method: foam core + carbon socks. I made a groove in the foam to fit a 9mm plastic tube to hide the rear brake cable. I am back on track for this new bike. The frame has been designed full scale on a sheet of MDF and I realised that the chain would not fit if the frame was to be built like my sketch. A clear film has been used to sketch possible modifications and improvements. A V-brake should fit the tight space between the crank arms. Chris King bearing will be used. I tried to enclose the wheel in the frame so it will be easy to fully fair the wheel for racing. Laurent Dechenne came last week to finalise the next bike for Marc Lesourd (Vipère). Marc is currently riding a 'speculos' made of steel by Laurent and this type of bike proved to be very very fast up-hill compared to a Baron so we decided to make a carbon version to give Marc an Edge for next year. The bike currently weighs about 12-13Kg and we should be able to make a much lighter bike at around 7.5Kg to 8Kg. Here is the result: Light weight carbon frame, semi faired front wheel, airfoild U handbar. The chainset will be enclosed in a box if we can. This drawing was produced about 3 years ago to show what could be done in carbone. The bike geometry was wrong but it opened a long discussion with Laurent Deschenne and a metal prototype was built.