I'm sure this is common knowledge on the forum, but I just can't help posting that the S1 is an incredible descending bike. The climbing is good, but the downhill is just simply amazing. It's so stiff, solid and in control with super tight cornering. The faster I go the better it feels. I just rode a 60 mile 5,200 foot climb and the downhill had me hoot'n and hollering. When I put the hammer down on the little rolling sections it takes off like a rocket. I don't have a bike computer yet so I don't know how fast I was going, but I kept turning around to look for cars. Nobody there. I've never ridden any of the other Cervelo models. Do they descend like this too?

 I am a crap descender... but not on my R3.  It's like being on rails compared to every other bike I've owned, and I can keep up with guys who are great down the switchbacks.

 I hope the SLC-SL that I'm putting together also descends nicely. Can anyone attest to that?

I am a bad descender too, but on my SLC, I am not too bad.  I guess the sold handling inspires confidence.  Since I got the bike about 2 years ago, I have become a better bike-handler -- probably a by-product of riding much more, because the SLC makes me want to ride.

Can't talk specifically about the SLC-SL, but I am sure it will be awesome.

In the summer a group of us went over the Alps. I was on my SLT (S1), and a couple of the others had Specialized Roubaix Pros.

Before I start, I have to say I am not a good rider, so this isn't about my skills, as I don't have any.

Descending from Col de Lauteret to Briancon, they left about 30 seconds before me. I set off after them, and caught them quite quickly, just in the tuck position, no pedalling after reaching 30mph. We were soon doing 40-50mph for 10-15 minutes, during which time I caught and passed them - they couldn't hold on, even in my draft. 

As mentioned, this had nothing to do with my ability. When we arrived at Briancon, we discussed the possible reasons:
- Body Weight? No; We all weighed around 170-180lbs.
- Components? No; We all had similar wheels.
- Bike Stability? No; We didn't need to brake anywhere, so confidence and stability weren't an issue.
- Bike Aerodynamics?  Probably; The S1's aero tubes have less drag, and at 40+mph that will be significant.
- Position? Most likely reason; The S1 is more aggressive than the Roubaix, and I can get very low indeed, whilst their positions are more upright.

Whatever the true reason, Me + SLT = superbadassfast down mountains :-)
...and very slow up them :-(

I'm not so sure about descending on my R3. it's an 08 stock model with DA 7800 and RS20 wheels. I think the problem is the cluster that came with the bike - must be for hill climbing, not descending. I've tried some pretty steep descents. I find that I spin out at over 70kmph (my max speed is 75, where other riders are managing closer to 90). Because my cadence is so high, it feels unstable, like i'm bouncing all over the road.

jacobyte, I have the same situation with the dudes I ride with. We all go fast on the downhill and I let them go first. As we go I pull to the side out of the slip stream and still have to tap my brakes to avoid going past. I don't think they are braking either since the road was wide open with no hazards. Next time I think I'll avoid my brakes and see what happens.

oldskoolbreakz:

I'm not so sure about descending on my R3. it's an 08 stock model with DA 7800 and RS20 wheels. I think the problem is the cluster that came with the bike - must be for hill climbing, not descending. I've tried some pretty steep descents. I find that I spin out at over 70kmph (my max speed is 75, where other riders are managing closer to 90). Because my cadence is so high, it feels unstable, like i'm bouncing all over the road.

 

I generally stop pedalling after I hit 65 km/h or so. Its more efficient for me just to tuck and let gravity accelerate me to terminal velocity. Pedalling affects my balance, stability and steering at those speeds. I'm around 90 kg (200 lbs) so gravity's pull works for me. As to corners, try taking a corner by leaning into the corner with your hips and legs, pushing down (along the downtube) on the pedals, using the downtube and wheels as a lever and using your upper body to help countersteer (keep your think about keeping upper body vertical if you need to, and lean your body forward if you need still more stability). This is how downhill mountain bikers take corners, and you can carve a nice turn  while maintaining good stability at speed.

Stop!

We simply can't compare bikes without taking into account factors like cassette, crankset, weight, bike set up (seatpost, stem and handlebar), wheels, tyres and tyre pressure! And a cycletfit assessment so you can set up your bike accordingly! I can honestly say that even the best bike out there will be a poor descender if the set up is not right.
In my case I can easily state that my 2009 R3 is the most stable bike I've ever ridden (+80 km/h). It goes down like a rocket. And I tried quite a few bikes.

Bike configuration:
Cervelo 2009 R3 size 54
DurAce 7900 cassette, 11-25 (the 11 is key to stability at high speeds)
Compact crankset Fulcrum RS, 172.5
Everything else is SRAM Red
Fulcrum Racing 1 with Conti 4000s or Zipp 404 tubs with Conti Competition
Pressure for the racing 1 (125PSI/120PSI), the 404s (140PSI/130PSI)
Stem Deda Zero100 size 120mm
Handlebar Deda Newton Shallow 42cm

I'm 68kg for 177cm. Inseam 83cm.

I hope this helps!

Let me also add that (I think) I'm a good descender.

Everything on my bike is stock except for an upgrade to Hutchinson Fusion 2 Tubeless tires (with Stan's tubeless rim tape and sealant) running at 90 psi. I'm 6-2, 175lbs and ride a 58cm frame with seat set just high enough so my legs do not fully extend during pedal stroke. In other words, a fairly standard off the shelf set up.

Does anyone have an idea which would be the better decending bike, a R3 or and RS. I an planning several rides in Colorado this next summer and want a bike that I can feel very confident in for fast decents.

Definitely the R3 if you are flexible enough to fit it properly with a stem angled down. This gives several descending advantages; lower CG, ability to shift weight for and aft more easily without losing aerodynamics and applying extra traction where needed.

 I keep an R3 in Colorado and have used it in the Alps as well. I have also ridden my S3 and SLC SL extensively in the mountains, they are set up similarly and all descend well. I use Edge 25Ts to Reynolds DV66ULTs, my only caution is aero frames and aero wheels at 55-60mph on a windy pass can be a handfull. Again being flexible (hamstrings) helps tremendously.

Alex G:

jacobyte, I have the same situation with the dudes I ride with. We all go fast on the downhill and I let them go first. As we go I pull to the side out of the slip stream and still have to tap my brakes to avoid going past. I don't think they are braking either since the road was wide open with no hazards.

It's annoying isn't it, you don't want to lose the momentum, but you have to. I was thinking again about how the bike simply carves its way down hills, like guiding a motorbike by shifting your weight from side to side down the perfect racing line, rock solid. I only get to ride my SLT once a week (business rules my waking hours), but just thinking about it makes we want to get out there and lay down some of my puny wattage. Maybe I should take this afternoon off...

Alex G:

Next time I think I'll avoid my brakes and see what happens.

Hmm, be careful out there, you don't want to do that on a gravelly country road with blind bends at 40mph; you might end up... end up. :-)