Trust the jig

 
One odd thing about working with bamboo is that no matter how straight you think the cane is, it always has some sort of linear distortion. This is especially true in my home-grown culms that come from up the river a piece. There is always a major distortion axis, and then a secondary axis of distortion that leaves me wondering if I've gotten the alignment right at the end. In this case, the seat tube bends mostly in the fore-aft direction, but also has a slight deviation left to right, which makes the seat tube a little off center at its midpoint, even though it is perfectly centered at the seat collar and BB junctions. My bet, I'll never notice it once I am astride the bike.

Natural bends

 
I've decided to try my hand at using the natural bends inherent in bamboo to my advantage. Check out the subtle bend of the seat tube to shield the rear wheel.
Wait till I post the seatstays, they've got hips.

Not straight

 
I'm kinda pissed that the vacuum bag screwed up my alignment. It looked pretty good to me! I'm finally getting the technique down well enough to do single-pass carbon layups. I did learn as I sawed this joint apart that there were some voids in the area below the BB shell, not enough to worry me about strength, but enough to make me think a bit about how much I have to saturate each piece of carbon before applying it.

Drillium Dropouts

 
I did a little bit of carving on the left dropout. I'm ever so slightly apprehensive about strength, but I think that the coolness factor outweighs that by a long shot. Worst case scenario involves a blowtorch and some pliers somewhere down the road.

Bicycles also abhor a vacuum

Things have been going great with my 4th bike, though I still keep learning the hard way. I have been getting a lot more systematic in the way that I lay up the carbon, rather than just going on my gut instinct as to what will be strong enough and then overbuilding, I actually did some 3rd grade math and came up with a target for thickness and I went from there. I try to do my layup based on my semi-intuitive understanding of the forces for each joint and the notion that carbon is strongest in tension. I even had the forethought to cut all of the pieces of unidirectional carbon to size and shape before beginning the layup process, and going so far as to separate all of the pieces that would go on the tops and bottoms, lefts and rights of each joint. This has made the process MUCH faster. I've also been able to capitalize on the benefits of using the vacuum pump to a great degree, and occasionally to TOO great a degree.
I did the bottom bracket on Sunday night and laid up the whole joint at once, wrapped the release fabric and the breather ply, then sucked all the air out. Things seemed perfect. I unwrapped it the next morning and it looked great, stiff and solid. Then I tried fitting a wheel in. DOH. The force of the vacuum had distorted my rear triangle together, spacing the rear wheel at something like 120 mm. Bad news. I should have put a spacer in, but I thought that I had folded the bag in such a way that the dropout spacing would be unaffected. Wrong.

I'm weighing my options to proceed forward, and have had a modest bit of success in heating the BB joint and spreading the chainstays, but I'm not sure about the future strength once I do that. Epoxy is only flexible to a certain degree, and I hope I'm not creating too much internal stress. I'll give Gougeon Bros a call to double check and then hope for the best. Worst case scenario involves a gargantuan amount of sanding and then re-setting the joints. That should be only about 5 extra hours of work, maybe.

Pour moi?

I've finally started working on a bike for myself, after over a year of dinking with carbon and bamboo. This bike is going to have all the bells and whistles, or at least as many of the bells and whistles as I can manage to put together in one bike. I spent a long time anguishing over the frame geometry to specially suit my weirdo ideas about bike fit. I'm a true believer in the arch cleat position espoused by Steve Hogg and Joe Friel and I believe that it has had a lot to do with my continued improvement on the bicycle as well as a vast increase in comfort. I also made the switch to 180mm cranks last year and I've really enjoyed that change as well. A little sluggish at first, but more power, plus a really low center of gravity have made cornering a thing of joy. This means that I am very low and far forward on the bike though, which has resulted in a bit of sloppiness up in the front end with my extremely long and strange 140mm stem.

I've also decided to go with a tapered steer tube on the bike, though I am not 100% sure whether or not to go with a 1.5 or a 1.25 up front. I'm mostly concerned with what will look good with the enormous headtubes that I've ended up using. To top it all off, I'm a believer in the BB30 system as well, and though I won't be able to get my 180 cranks, i don't think, I'll be able to get a set of SRAM Red cranks in 177.5 which may be the sweet spot for me, we'll just have to see.

 

Sunset on the prairies. I was thinking of the Henningsgaard farm north of Bemidji where we passed several pre-preseasons and a most excellent Newyears, as well as Jude and Michelle's wedding.