Starting from a 73 deg seat tube angle, it's approx 1 cm per degree difference per 60 cm distance from the rails to the BB spindle. So 72 cm to 72 degrees would be 1.2 cm shift in required seat post offset.

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http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

Great build.

Any info on your expereice witht he AX stem would be great to hear.

There are not too many actually ride reports on it.

The R5ca geometry is the same as the R5 and 2011 R3 assuming you use a zero-offset seatpost. It was designed to specifically to allow weight weenies to use a lighter, zero-offset post. So only an extra-long femur would place the rider back far enough to use the the typical 25mm offset post unless you want to rotate your entire body to a more upright position. I think you'll find this frame is as tough as they come and one of the stiffest in BB and torsion out there. Anxious to hear some ride reports!

Just starting to plan a weight weenie bike for myself so I'll tune in regularly. (Full disclosure...I work for Cervelo's engineering group but any opinions are solely my own!)

Nice bike Sedluk!

I've just bought a R5 and was wondering how straightforward it was to fit the VumaQuad crank? Did you have to use the SRAM/Rotor BB and spacers etc. that came with the frame or does Zipp produce a specific BBright BB? No-one over here in Oz seems to know and the Cervelo website isn't very clear.

cheers

Beautiful!

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"black on black, is a crime"

GREAT looking build!

Those frames feel like they're going to float away in your hands!

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2011 Trek Paragon 29er | Reba XX 120mm Fork | XX Drivetrain | 160mm White/Carbon Exiler CR Brakes | Thomson 90mm Stem & Post | Easton Monkey Lite Bar | X.9 Hubs to DT Swiss X470's | Schwalbe Rocket Rons

The VumaQuad crank install was pretty easy. The R5ca has press fit bearings already installed from the factory. The BB on the frame does not have any metal, the bearings were pressed into the carbon BB. There was one bearing seal on the non-drive side, a bearing seal on the drive side, a 11.5mm spacer and a wavy washer the best I can remember. The crank was perfectly centered with that and ready to go. So far I like the crank, dropped the chain once while down shifting, I will adjust the front derailleur now that the cables have a few shifts on them. Rode 105 hard miles on Saturday.

I have ordered an Ax Lightness premium no setback seatpost, will see if that will fit. I will want the seatpost to secure to the carbon wrap on the saddle rails. It looks like it will be close but might work.

I have ordered a couple of headset to try out. The AER headset is not for me. It may be lighter than air but is not really suited to my kind of riding. It is very finicky. The norglide easily gets off track. Not a problem, the headset is a standard size and I will try out some light headsets with bearings. Maybe the FSA Orbit IS or another Cane Creek, I have ordered both.

I rotated the handlebar up a little and will move the shifters forward on the handlebar. The stem will be lowered a little. Once I get comfortable I will cut the fork tube down some more.

Cane Creek sent me one of the first Aer headsets and I never had issues with them. --> http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=61381

Now I got both the Aer ZS and the Aer IS. Once a NorGlide bushing was worn out and subsequently replaced. I'm so pleased with this product that I'll use the Aer on my next bike too.

I'm not exactly easy on my stuff. Back in '08 I got myself a pair of VumaQuad cranks whose spline interface I ruined relatively quickly into service life. I think it took mere months. They developed excess play in the arm interface that basically rendered them useless, even though they were otherwise intact. They correctly installed but since the failure I never touched them again. I ended up donating them to a friend as they never worked properly for me.

It's like the saying... different strokes for different folks.

The interesting thing about the R5CA geometry is the seat tube is set-forward, so it's not a pure 72 degrees:

_________________
http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

Sedluk that is one awesome machine, black logos on the Lightweights would just finish it off nicely. Weight is phenomenal without being for show only.

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Ozrider - Western Australia
Parlee Z5 XL 2011 (6055g/13.32lbs) Raleigh RC Ltd 2008 (7.6kg) Reynolds 653 Custom 1990 (9.8kg, now 8.8kg)
The accumulation of marginal gains is what makes the difference between winning and losing

Still cant understand why this hasnt been made a StickY

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i like people... i just can't stand assholes

Here's that plot again, but I drew a line along the seat tube:


It appears the intercept is 1 cm ahead of the BB center.

So the effective seat tube angle is:

STA = arccos [ cos 72° ‒ 1 cm / L' ]

where L' is the distance from the top of the saddle to the height of the BB center along the seat tube.

The derivative of arccos = ‒ 1 / sin, so I can approximate that as:

STA = 72° + [ 1 cm / ( L' sin 72° ) ] 180° / π
= 72° + 60.2° cm / L'

So if L = 73 cm, for example:

STA = 72.8°

So it wouldn't be that different from the R5, actually.

_________________
http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

This is impressive Mr. M. I heard about it and now I see why J. is raving about it so much. Nice setup!!! Have you tried the Tufo Elite 23 tires? I really like them and at 250g you"l be saving a bit more weight, not that the R5ca doesn't suffer from acute anorexia, but just a thought... I'll see you soon man!

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MASTER says... FASTER!!! ...but my leg still hurts...

I like!

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Baum Ristretto, Baum Mondrian Corretto & the '89 Merckx! | "If you could eat it in one sitting, hold your line." | twitter.com/Tinea_Pedis

Sweet build!

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Mr.Gib wrote:

I think this is where you are making a mistake. If it was my money I'd be looking for a frame that climbs like a scalded baby monkey on amphetamines. A goat on steroids will just not be as fast uphill.