@eerock- that is a sweet bike (the new giant) you will love it.

@shlammed- are you going to heat treat the frame? is the local oven big enough to fit a tandem? Also I'd recommend running 203 rotors for the brakes... not a big weight penalty, and you get a lot more stopping power. Please do a build thread if you go for it.

 

Tandems, awesome to ride yet awful to ride around.

 

Cool downhill pics, I'd love to do that but don't care to break anything else.

 

I wonder if you put two elite riders on a tandem built the same way as a top level bike and had them race another elite rider by himself who would win. Power to weight and power to drag should be better on the tandem, no?

 

The tandem would crush. They are freaky fast if you put two even moderately fit people on one.

 

FWIW, wife and I rode a 26" wheel'd tandem with suspension everything, cruiser handlebars and hybrid city tires FASTER than I ride my carbon ultrabike, and it was considerably less work.


At one point, we decided to put it down to see what we could do at our normal effort and cruising speed with this plush 50+lb semi-offroad bike was about 45km/h (30mph) on flat ground. We could go faster, but we decided against it.

They are super fast. IDK if it was because we were cruising or not, but we really seemed to slow down for hills.... back to carbonbike speeds.

 

I think 6061 needs treating, but 7005 aluminum is age treated. so wait a month once the frame is welded and it should be good.

from my reading anyways... I haven't used 7005 aluminum before that I know of.

 

yeah, 6061 definitely needs heat treat... maybe you can get away with age-hardening the 7005. Just be careful- we built some welded aluminum stuff in college (not sure what alloy)- no heat treat and it was incredibly weak.

Coming from someone who has built a bunch of frames- you can't go wrong with 4130... cheap, easy to get, easy to work with and the bikes aren't that heavy

 

4130 still needs to be tempered at the welds. whether you have them put it in the oven of you do it yourself with the torch is up to you.

At least the 4130 only needs to get put in the oven and practically any decent heat treat place could fit that frame. With 6061 it needs to be solution heat treated and at least up in new england the closest place that can do that is ohio.

 

Me and another dude, let the heckling begin, showed up to a group ride on my tandem one Saturday morning. Pulled just about the entire ride and won the sprint. We could cruise at 27-28 mph without too much effort. And on a false flat downhill...it was scary fast. But, then, you're two dudes on a tandem, and for all the speed glory it's still kinda uncomfortable.

 

I ride my bike to hop around, carve, and have fun; so tandem just doesn't sound so cool to me. However, it does sound like the fastest and most efficient way to get from point a to b. At least shlammed is riding his with the wife, because when I think about riding one of these with my GF it sounds fun. Riding one with most of my other riding buddies on the other hand sounds terrible, and we'd be arguing over who has to ride bitch (or bottom, what do you call that?)

EErock, sick bike man. I bet that thing will mob over just about anything. My brother has a 2012 trance 26" and it is a great bike. That one you got has more travel and bigger wheels, so I'm sure it will kick ***. Heres a pic of my bros bike,:



It's put together much better now, this pic was taken right after we threw that bike together. Maestro feels nice.

Also my buddy has a kickass 2012 giant reign. Probably closer to what your bike feels like, to be honest. That bike is plush as hell up and down the trail. My bike has the upper hand on fire roads and long smooth climbs, but the way his bike climbs up the technical stuff is crazy.

 

In theory you should, but I made a bunch of 4130 frames without any heat treat... a few cracked (generally from bad gusset placement) nothing broke catastrophically, and I did many stupid things on these home-made bikes...

 

If you're not going to at least torch temper something welded up with 4130, then you might as well just go with 1018. The amount the frame flexes will be the same and it'll be less likely to fatigue fail. 4130 really shines when you send it to the heat treaters and have them normalize the whole part after welding.

Question on geometry. Laying the steerer tube back vs moving the front wheel forward. Layback (like caster in a car), makes the steering more stable at speed and slower to turn in right? Where moving the wheel forward of the axis makes it want to turn (like a swivel caster wheel). Right? I'm trying to take a 2 wheeled vehicle that has nearly upright steering geometry and make it travel at a speed like 10 times higher than it was designed to, and I'd prefer to not kill myself.

 

Thanks guys. I'm really excited about it. TBH there were two bikes on my short list due to how they were priced. This bike, Norco Sight and Kona Process 134.

The process was a pretty amazing bike but the price point and build out wasn't for me. If I had the time/patience for a frame up build that's probably the direction I would go.

This bike checks all of the geometry options I was looking for and has a decent starter build out. Other than the mostly terrible damping units on the new bottom of the line fox stuff... I have no real complaints. Ultimately The Path here in Tustin made me a deal that I would be absolutely stupid to turn down. Ended up with this thing with a rock shox reverb seat post, Trail Adjust fit damper unit in the fork, an odi 50mm stem, and Shawalbe tires thrown on it for under 3k out the door... Oh and 12 month no interest financing.

 

There is a delicate balance with the head tube angle/fork rake (combined to measure into "track") there are guides to stay in as a general number.

One is twichy but doenst jack as you turn the wheel (low caster) one is more stable at high speeds but has turn induced jack which if excessive (like in a chopper motorcycle) can feel odd and handle like complete dicks.


Standard for frame bits is either 6061 or 7005 to be able to buy pre-made dropouts/tube/etc. I would prefer to buy pre made things like this because im not going to be building a bunch of them and they are quite economical.

6061 definitely needs heat treating for a frame. 7005 I read on frame building websites as being optimal for diy builders because it age treats. I will be looking more into the options once I have it designed better but until then I will be designing based on 7005 alu based on these reasons.


I just wish I could find one of the chainstay mounted disc dropouts for aluminum frames.


So much cleaner looks and I assume its a bit more aero (which is one of the goals of a custom build here) Aero wheels, handlebars and frame tubing I hope that this is a high speed bike that we can cover a lot of ground on.

 

Cool man. I like the process as well, nice looking bike. I've been drooling over these new machines coming out, they've really made some strides in the last 5 years.

One day I'll buy something super badass, but for now I'm sticking with my 2009 Titus for a bit longer, and I may even play with a better fork and/or angleset to see if i like a slightly laxer head angle. The current setup is around 69* HTA and it really hasn't held me back much, but i cant help but think a 68* angle with a NICE 140mm fork (instead of the 130mm cheapie fork i have now) wouldn't destroy my handling, and add some DH confidence.

 

Found this today in my searchings. A co-motion custom spec'd frame geometry.
(large picture so I wont embed)
http://cyclingabout.com/wp-content/u...012-804-PM.jpg

When I took this draft into CAD, referenced it in and scaled it, drew the main tube center lines and placed the lines over my newest design I get:




Looks like im on the right path with this frame geometry.

 

that tube that goes from the middle of the steerer tube to the rear crank tube makes me cry. It needs to connect to the steerer tube at the same node as the top tube.

 

I honestly don't think it would make much of a difference. the head tube is relatively thick walled tube vs the top tub that would be 0.9mm thick. if you noded them together you might have issues with welds ripping between the 2 thin tubes.

That being said, my design uses a much shorter head tube, so if I had the diagonal it would almost be a continuous node.

 

So I'm looking at one of these. Full carbon, hydraulic discs (yay, brakes), Ultegra 11s. Not enough orange but I can work with that.