thanks for the question. here's a photo of what is being welded into the frames. Two of these (on the left) come from Paragon Machine in California as they serve a large portion of the framebuilding community. The others I turn myself to suit my needs. These pieces are pressed into the frame with a very tight fit (once they are in, they don't come out, even before welding). Then they get welded. Many welders file the weld off so you don't see any connection. I purposely leave the weld on my frames in some areas due to the heavy moment lever on the frame in this area which is notable. They have a larger wall thickness when compared to the 0,89 tubing that they get pressed into. This serves as reinforcement as well as giving the precise measurement of the seat post.
I don't use double-butted tubes as you describe for a number of reasons:
1. They use oil to lubricate the tubes in the butting process because of the high pressure turning of the mandrels. While you can superficially clean the interior of these tubes with detergents and ultrasonic solutions, the oil penetrates at a microscopic level into the grain structure. When you go to weld the tubes in the joining process, you heat the whole tube and these residual oils evaporate into the frame (on the inside). Now you've got a contaminant circulating inside the frame where you need purity. This will compromise the weld at some point because you have these residuals in the heat affected zone as they are drawn in at temperatures over 600C.
2. One of the more prominent butted tubes on the market has an outside diameter of 35.3mm and a wall thickness of 0.85mm, very similar to the straight-gauge tubing which is normally available. This means that the use of an aluminum spacer will be necessary to reduce the internal diameter to allow for the insertion of the seat post. Many higher volume manufacturers use this because of a lower labor/manufacturing cost. The problem is that while your seat post is nice and snug, but you've got that huge lever ( 80 kg rider in the saddle) working on 0,85mm of material that has been welded and weakened. The spacer doing little to counteract that force. On ti frames that I've seen fail, this is one of the most common areas of weakness.
3. The i.d. of the butted tubes is around 33.6mm. Not bad if you need to reduce down to a 31.6mm post, but if you've got the need for a 27.2mm post or smaller, you'll be inserting a spacer with a wall thickness of 3.2mm, which is not practical or nice to look at. I build quite a few frames with 27.2mm.
4. The butt lengths on these tubes do not correspond very well with some of the various sized frames that I build. For example small mtb's with short seat tubes would have the butt locations drastically different wrt a road bike of a larger size.
I hope that gives you a good idea of the what and why. Thanks again for the great question!
I'm not sure if you're aware, but Iditabike 2012 has started and we've got our friends (and Crisp-sponsored riders) off on Sunday. You can follow them here:
and the homepage for the race is here: Iditarod Trail Invitational-home page (i'd recommend checking out the video posted by Mike Curiak from last year. His video/photos are always worth the time).
Also Auslilia has posted some training photos and words about her preparation here:
All of the following photos came from here blog. I know there are a lot, but I think they really give a taste of how passionate these kids are about what they are doing.
a taste of the cold:
Sebastiano preparing his food rations for drops along the trail..
Seba and Ausilia training near home preparing for the long journey..
can't finish with a snow shot..
Hey, thanks for looking. And a big thanks to those kids for sending me the shots from training.
Bespoked Bristol news? Well, I'm going to have a fast roadbike with new graphics. should be pretty nice for the "modern" ti roadies to look at. Belt drive gelato-fetchr and some other goodies. I've been done with the bikes for over a month. It's the shipping and logistics that is going to make news!! What a headache...
Looking forward to seeing you there!
Hey j44ke, funny you should mention. This note just came home from school with my oldest girl, from her teacher:
Paraphrasing, it says that on the 9th of March, the roads around her school will be closed in both directions due to the T/A race (that's Tirreno/Adriatico for those of you with your mind in the gutter..). I don't really have to go far for that race as it passes by my town. Last year, I forgot the date and was pleasantly surprised and got to chat with some fellas while visiting the hardware store:
After that chat, Fabian Wegmann became one of my favorite racers. What a super-nice guy.
Here's my BLOG POST of that encounter. I actually posted this in Velocipede, but mistakenly erased the entry photos...sorry bout that. There are some more photos taken from last year's encounter at the local hotel where all the teams were staying.
As for Strade Bianche, I've yet to visit that one. I've built two frames for some of the guys who organize the race (they also to the Eroica and various Rando events) and they've invited me numerous times, but I seem to miss that event every time. It is quite an impressive site seeing them cruise along the dirt roads with the dust trailing up behind them, something like a Looney Tunes cartoon. Will have to make that trip soon..
thanks for the questions..
Don't worry Darren....you know that I have my "007" if I want to know if you're well and obviously what you're doing....glad to know that for Bristol quite everything's going well....now let's send to Castiglionfiorentino some Paparazzi and have a preview for the v-salon guests......let's keep in touch for Bristol man!