Your latest bike project?

[mstone]

Assuming no change in temperature, the absolute pressure in the tire doesn't change, but the the gauge pressure (pressure relative to the ambient, or atmosphere) will change. On the ground, the ambient pressure is 14.7 psi, so even if you were to fly to vacuum of outer space where the ambient pressure is zero, the gauge pressure of the tire will increase 14.7 psi.

And then your eyes will do this: True fact.

[hozn]

It stays the same*. The air pressure outside of the tire air chamber drops. The sun does not go down the horizon goes up. The most it could drop is 14.7 psi but if that happens that is the least of your worries as the aircraft is no longer in the earths atmosphere. OTOH the view would great! If I had tubeless I might drop the pressure a bit but not much. There is a risk of having a bead be pushed on by some other bike part or other luggage, unseat and drool tire slime all over the bike.

* I bet the internal pressure does drop a little as the air temps in the hold will drop.

Yeah, I might add a bit of air. I dropped them down to around 20psi (normally 50ish); they are holding on well, but the risk of losing the bead is a real one. On the way home I will definitely let out the air as it'll help the bars / brake hoods fit a bit easier. I guess worst case I'll arrive to a few oz of sealant in the suitcase and be back where I would have started with tubes.

[Vicegrip]

A small price to pay for good memories of a cool adventure.

[hozn]

A small price to pay for good memories of a cool adventure.

I chickened out and let out the air :-) it wasn't the risk of sealant everywhere as much as the risk it was incurring to my brake hoods (reservoirs), pushing them against the top of case.

I can run with tubes until I am able to swing by the bike shop and borrow their floor pump.

[Vicegrip]

Forgot about the hydro brakes. Are they the no air type reservoirs? Any air will expand by about 50% volume with air pressure at a bit over 6 rather than 14.7.

[hozn]

Forgot about the hydro brakes. Are they the no air type reservoirs? Any air will expand by about 50% volume with air pressure at a bit over 6 rather than 14.7.

Yeah, hopefully they are still well bled [so there's no air in them] and I won't have any issues with those. On the whole, I would say that if I were going to travel frequently and cared that I be able to pack and setup quickly, I would strongly consider a rim-brake bike. But I will really enjoy having my hydro brakes and this bike is my commuter*, so I'm happy to spend the extra time removing the calipers, etc.

Things that make packing this bike a little more involved:
- 6-bolt rotors slow to remove. I was going to do CL rotors; however, doing that means I have to carry a BB tool and a cassette lockring tool, which are both pretty big/heavy tools.
- Remove the calipers and hoses, though the zip-tie stops worked perfectly and made hose removal a 30second process.
- The 135/142 OLD for rear hub is obviously more than a standard 130 road hub; every mm does matter a little.
- Big-range cassette (11-40) definitely leaves less flexibility for frame part placement.
- Hydro levers have tall hoods.

But I have done it a few times now so I have a system. *Love* the Copilot case.

Without air in the tires fitting things in the case almost felt too easy. Even with a few kits, shoes, pump, greases & lubes & sealant, lights, etc. still comfortably under 50lbs. Heck, I could have probably put my fenders in there. I might leave the fork on next time, as that might work (the front triangle fits fine; the only issue was that with fork on the downtube passed right over the center point of the case, which is really where I'd like the cassette to be for the rear wheel (face down against the bottom).

* The coupler frame is my commuter frame currently, though I've decided that I'm going to get a second identical frame w/o couplers. The way I ride/abuse my bikes, I think that makes sense. So switching to use the coupler frame will just mean taking the crankset off the one bike (everything else has to be taken off anyway). If I end up traveling more, I'll just get a second crankset for the travel bike so I won't even have that to swap.

[TwoWheelsDC]

Latest upgrade project became two projects. Most importantly, I'm upgrading my Cervelo to Ultegra Di2 for my birthday. I don't have the mech yet, but I started the prep work, and upgraded the brakes while I was at it. I already have Ultegra wheels, so I'll be full Ultegra (excepting the Rotor crank) when it's all done.




The second project is taking all the 105 stuff from the Cervelo and putting it on my old Cannondale that my wife sometimes rides. This bike is a great frame, but came with a Sora triple groupset in 2003. I had to buy a new crank and BB, but the shifters, FD, RD, cassette, and chain are all getting transplanted, so it was a relatively cheap upgrade. The only complication is that my existing 105 FD is a braze on, while the frame requires a clamp, so I had to order an adapter. At this point, I'm just waiting for the clamp and new shifter cables and then the Cannondale will be ready to ride.

The pics suck, but the bikes aren't done so it doesn't matter.




The new mech for the Cervelo will go on on Wednesday, but the wires and junction boxes are shipping from Germany, so hard to say if they'll be here by then.

[TwoWheelsDC]

Thx Cannondale is done! Still waiting on parts to finish the Cervelo.



Found a photo of how the bike looked when I bought it (except the wheels). This upgrade has been multi-stage, replacing the silver parts with black/new stuff. Only thing left is the headset and I'm in no rush to do that.