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Jean-François’ XACD singlespeed hardtail

Olivier mentioned to me that he’d seen another chap over on the French forums getting an XACD frame made and put me in touch with him. This is Jean-François’ singlespeeded hardcore hardtail:

Jean-François singlespeed hardtail XACD frame.

I asked Jean-François what the thinking was behind his frame:

I have a Yeti 575 which was perfect in the Midi-Pyrénées, but as I’ve been living since last September in a flat and rock garden free region of France, it was too “suspended”. So I wanted a fun bike that wasn’t too XC oriented. I wanted a quite low bottom bracket (315mm height), a head angle of 67° with my Pike, and a rideable geometry with a 100mm fork if I changed my mind about fork travel. So I used Bike Forest CAD to design the frame with the Pike and when I checked the geometry with a Reba length fork it was not out of bounds (the BB was 300mm high and the head angle was 69°).

I adjusted the top tube length to be a bit shorter than my 575 in order to be more fun in tight turns. As I’m quite long in the leg I didn’t want a too short a head tube, and as I wanted a comfortable bike I chose 425mm chainstays.

After this I used Bike Forest CAD to compare my geometry with some other bikes, I saw it was quite similar to frames like the Chromag Sakura so I was pretty confident it would be OK.

I designed the frame for gears but ended up running it as a singlespeed. I didn’t want horizontal dropouts and so on because I’ve never tried singlespeeding before. But I have to say I’m astonished by how capable a singlespeed is! The next frame will have different  dropouts, maybe some Rolhoff ones for greater versatility.

The head tube reinforcement is not very attractive but I didn’t know another way of doing it. I’ve chosen the tubing diameter to be a bit bigger than the standard XACD frame because of the nature of the bike and because of my size (1.84m and 84kg). The frame weight is 1.8kg.

I’ve not ridden a hardtail for a very long time (since 1998 or so) so it’s not easy to compare but I’m very happy with my choices. It’s a stable bike but fun in corners. I think it would cope well with more technical trails but haven’t had the chance to try it yet.

To conclude, I want to say it was nice to deal with XACD, the speed of service is amazing and the results are really close to my requirements.

You can see that  Jean-François started out with a clear idea of what he was after and was able to reference similar frames to check his numbers. I think he’s made a fine job of a longtravel hardtail frame and the handling certainly seems to live up to the numbers.

If he finds any flex in the front end then ‘mark 2’ could perhaps use a larger diameter down tube, taking it up to say, 45mm diameter, with tapered ends. Putting the larger downtube on would also mean you could probably do away with the re-enforcing plate to the headtube, although I don’t think they look out of place on his current frame.

The only other area Jean-François had to be careful with is around the seat tube junction. If you go for a dropped top tube design just make sure that the bottom of the top tube doesn’t go lower than the 100mm long sleeve that they fit inside the seat tube. You can see from the drawing it’s about spot on here, some people take it too low which can increase the risk of the seat tube failing due to the stress inbalance.

Jean-Francois frame drawing.

Has Jean-François’ frame inspired you to have a frame made? Or maybe you’ve already had a frame made by XACD – let me know if you have as I’d love to feature it in the Gallery section.