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Cervelo S1 2009
By Tom Demerly.
Read this first about our reviews

Cervelo S1 2009

Cervelo's 2009 S1 is a great riding road bike with tri-bike capabilities that add value and versatility.

Review Note: You’ll see a new look to our reviews for 2009. We’ve built a new studio specifically for our product photo shoots. The new photos will show greater detail where we can control color and lighting more accurately. We can devote more time to photographing details since we aren’t relying on weather for good conditions. We hope you find the new photo format useful. As always, we write and photograph all our own reviews.


Tri bike or road bike? Which one should you buy? Will any one bike work for both road and triathlon?

Those are the questions first time buyers ask when torn between the idea of a more aerodynamic position and better, more efficient running off a tri bike, but more responsive handling and greater versatility for group rides on a road bike. Each bike, tri bike and road bike; has its advantages and disadvantages. Is there one bike that does it all? Cervelo’s S1 is probably the one bike that comes closest.

Cervelo S1 2009

Cervelo S1 2009

Shown stock on the left, and converted to a triathlon bike on the right, the 2009 S1 has exceptional versatility as a dual-use road and triathlon bike with impressive performance in both configurations.

“Is there one bike that does it all? Cervelo’s S1 is probably the one bike that comes closest.”

When considering the differences between road bike and tri bike it is worth examining the balance sheet of pros and cons for each bike type:

Road Bike


Tri Bike






Quick steering optimal for group rides.
Rider position is not as aerodynamic as tri bike.

More aerodynamic body position for solo riding saves significant time.
Too stable for quick, responsive cornering.

Optimized for good climbing in and out of the saddle.
More difficult transition from cycling to running.  
Steep seat angle symmetrically fatigues legs and results in fresher legs for faster run split.
Not suited for group riding where road bike riders may be uncomfortable riding in close proximity to tri bikes due to slow handling.
Best acceleration to respond to sudden changes in group ride tempo.
Less comfortable position/weight distribution for longer rides.  
More stable for high speed, efficient, easy straight line riding.
Some riders may not climb as well on tri bike as road bike.
Superior high speed cornering (compared to tri bike, which is more stable).
Generally less aerodynamic frame configuration on most road bikes.
Easier to stay in the aero position due to hip angle.
More comfortable position with better skeletal support of torso for long rides.

The aerodynamic story of Cervelo is well known. They started with aerodynamically optimized bikes: Bikes with valid aerodynamic benefits- not just aero styling- genuine innovations that make the bike faster. Another part of the Cervelo story is less conspicuous but equally as innovative.

Most Cervelos use less conspicuous technology that optimizes specific performance goals. The innovations are subtle, often hidden, and generally poorly hyped by Cervelo. Most of the benefits are hidden from a marketing perspective, but become apparent to the rider after they put miles on the bike.

Cervelo’s 2009 S1 is a treasure trove of hidden engineering gems that achieve a myriad of subtle design goals. Bottom line: The S1 has a broad spectrum of capabilities achieved through small engineering details that result in significant benefits for the rider. The S1 is a bike of small details that make it the most versatile aluminum high performance bike available.

“The S1 is a bike of small details that make it the most versatile high performance bike available.”

Cervelo S1 2009

SmartWall 2: The hidden advantage to Cervelo's aluminum tubing, has been proven in Ironman triathlons and Tour de France stages. Note the horizontal internal stiffner added in the bottom bracket area for improve performance.

Cervelo S1 2009

The unique tack-welded chainstay bridge that adds stiffness and durability while relieving stress on the chanstays: A subtle, elegant engineering advancement. These two sophisticated, hidden details add significant performance.

The S1 is born from a concept bike that launched an entire category for Cervelo- the “convertible road/tri bike”, continuing forward into their current flagship S3 carbon fiber bike. The S1 is so advanced that, as its previous aluminum version, the Soloist, it has been ridden in Tour de France stages. Highly evolved carbon versions have dominated at the Olympic level. This is not an entry level bike. At $2199 MSRP it is entry level priced.

The S1 uses Cervelo’s proprietary SmartWall 2 aerodynamic tubing to achieve light weight, comfortable ride quality, excellent bottom bracket stiffness and optimal low speed aerodynamics. Smartwall 2 is a legacy tubeset for Cervelo, proven over and over in everything from the P3SL to the new P1. It is subtle, elegant, advanced engineering. Most features of the extrusion are not visible from the outside of the bike. The proprietary profile of the tube, typified by the sharp trailing edge, is the conspicuous feature of SmartWall 2.

Cervelo S1 2009

The S1 began life as a bike that has gone on to inspire advanced Cervelo designs raced in the Olympic Triathlon in Beijing.

The SmartWall 2 downtube on the S1 is substantially thicker on the sides than on the leading and trailing edge to improve stiffness while retaining comfort. The bottom line is the bike accelerates well but soaks up the bumps. Forget what you know about how aluminum bikes ride. The well conceived geometry combined with the SmartWall 2 downtube provides a degree of comfort unheard of in an aluminum road machine. Any question of durability surrounding aluminum frames has been answered by Cervelo’s lifetime warranty on this frame.

While the SmartWall 2 tubing is proven engineering it is not unique to the S1. The features that give the bike “convertible” geometry from road to triathlon make this bike unique.

Cervelo S1 2009

The minor, rearward offset of the bottom bracket enables a wider range of effective seatpost angles on the S1. This is the feature missing from standard road bikes.

Firstly, you can’t convert a standard 73 degree-ish seat angle road bike to a triathlon bike simply by moving the saddle forward to “induce” a steeper seat tube angle and then bolting on aero bars. Early attempts at this included the use of forward angled seatposts. These forward bending seat posts put too much weight on the front wheel making already responsive road bike steering downright dangerous. Weight distribution of the rider wasn’t correct for safe, stabile riding in the aero position.

A unique feature of the S1 that enables it to be ridden with aerobars is the rear-offset bottom bracket shell. The rear offset bottom bracket is the single feature that makes the S1 so adaptable.

If you look carefully at the seat tube where it plugs into the bottom bracket shell you’ll notice a distinct rear curvature of the seat tube into the bottom bracket. The center of the bottom bracket actually sits behind the center of seat tube by 40 millimeters. Used in combination with the carbon fiber variable geometry seatpost the range of adjustment for the seat angle is well over 3 full degrees, ranging from 73 degrees to 76 degrees according to Cervelo’s geometry chart.

Functionally there is the ability to get much steeper than 76 degrees while still retaining good handling and stability. We typically use a Profile Tri Stryke saddle to induce a few more degrees of effective seat angle since the Tri Stryke is 30 cm long as opposed to the 27 cm long San Marco Ponza saddle that comes stock on the S1.

Head tube length on the s1 is higher than Cervelo’s P1 and P2 bikes, the pure bred triathlon geometry bikes. That means getting high enough on the front end of the S1 with aerobars won’t be difficult but getting very low will require using a low stack height aerobar, perhaps one that mounts underneath the drop bars with very low elbow pads along with a low rise stem.

It is the frame and unique switch-blade geometry of the S1 that make it unique. The component kit is upgraded from previous years including Shimano’s new ice gray Ultegra SL STI shifters, front and rear derailleur. The crank is the FSA Gossamer compact, adding more versatility to the bike with a wide, functional gear range.

Click on this diagram to see how the rearward curving seat tube on the S1 makes it more versatile than a conventional road bike when ridden in the aero position with aero bars.

Cervelo did use the Mach 2 brake calipers from Tektro on the S1. For reference this brake is similar to the Tektro R530 caliper sold under the Tektro label.

Unlike the P1 triathlon bike, where the brakes are actuated by brake levers without return springs, I would have liked to see Shimano Ultegra SL calipers on the S1 since the return spring in the Ultegra SL STI brake lever is specifically tuned to work with the Ultegra SL brake caliper. There is a cost associated with this change since the Tektro/Cervelo brake calipers would retail for approximately $59.99 and the Shimano Ultegra SL calipers retail for approximately $139.99. Is it worth the $80 upgrade? No. There are other places to put $80 on this bike that would make a more tangible performance upgrade.

Cervelo S1 2009

Cervelo's Mach 2 brake by Tektro is excellent with non-spring loaded aero brake levers and adequate with Shimano's spring loaded STI lever.

Cervelo S1 2009

The workman like Shimano R500 wheelset is sturdy, reasonably light and works perfectly as a do-everything wheelset. 3T Funda fork also shown.

Wheels on the S1 are the tried and true Shimano R500 Aero wheels shod with the ubiquitous Vittoria Rubino tire. The tire spec on the S1 has been subject to change and still appears on Cervelo's website as the Vittoria Diamante Pro. This, apparently, is the reason for the line under the bike specifications on Cervelo’s web page that reads, “Specs may change without notice”. The older Diamante was a low end tire. The new version of the Diamante is a 220 T.P.I. (Thread Per Inch) tire that weighs in at approximately 195 grams according to Vittoria’s website. Cervelo split the difference on the tire spec between the old, heavier version of the Diamante and the newer high end 220 T.P.I. version by using the Rubino. this is the tire also used on many Felt models and, while we've never been enamored with its longevity, it has nice ride quality.


Cervelo S1 2009

Cervelo S1 2009

The road version of the Selle San Marco Ponza is a fine road saddle but won't suit most people riding in the triathlon position.

The road version of the ubiquitous Selle San Marco Ponza makes another appearance on the S1 and it is entirely adequate if not darn nice in the road configuration. When we reconfigured our S1 for aerobars in the steep seat angle orientation we did use a Profile Tri Stryke saddle for its additional length and padding when seated on the nose in the aero posture. The road version of the Ponza won't cut it as a triathlon saddle for most people.

Cervelo S1 2009

Cervelo S1 2009

The drop handlebar that comes stock on the S1 is truly excellent with a fine anatomical bend and flats for excellent comfort along with a very nicely relieved stem. These bars are among our very favorites.

The S1 comes with a road cockpit built around the excellent 3T Ergonova handlebar and ARX Pro stem. This is a fine set of controls. The bar uses an interesting ergonomic bulge shape to increase contact with your hands and improve comfort. It works- this is the nicest stock road handlebar on any road bike I’ve ridden. The bars are 7075 aluminum with a short 123 millimeter drop and 77 millimeters of reach front to back. More importantly, I found the bend and drop to be absolutely perfect for me when I ran the stem on the P1 bottomed out with no spacers. This is an elegant way to configure the front end and cuts down on conversion time switching over to your aero cockpit. Finally, the 3T Ergonovas are one of a number of new handlebars specifically designed to work with a Shimano STI lever. The transition from the tops of the bars to the STI levers is perfect- flat and wide, plenty of surface area to soak up road shock and provide good comfort. Cervelo did an excellent job with the controls and cockpit on this bike. The ARX Pro stem is also oddly nice for an original equipment stem with nice, skeletonized details for weight savings and good mounting hardware.

The drivetrain on the S1 is Shimano Ultegra SL, a fine transmission set we reviewed in excruciating detail here.

The crank is a compact 110mm bolt pattern FSA Gossamer with 50 tooth big chain ring and 36 tooth small ring.

This is a versatile gear range that gives you a top end gear of 122.7 gear inches which moves the bike 32.1 feet across the ground for every revolution of the cranks in the biggest gear. By contrast, a traditional road bike large gear of 53/12 would only provide 119.2 gear inches with a total development of 31.1 feet of development (distance covered by one crank revolution).

In short, the 50/34 is plenty of gear for high top speeds but a nice, low gear for easy climbing. The 34/23 low gear provides a 38.2 inch gear that travels 12.7 feet every time you turn the pedals. Contrast that with a typical 39/23 that travels 18.0 feet for every pedal revolution.

Simply put, less travel is better at the low end but more travel is better at the high end. The compact cranks achieve both agendas while reducing weight and improving shift quality. It is a 100% win-win component specification that makes a lot of sense in both the road and triathlon configuration.

Cervelo S1 2009

To set up the S1 as a steep seat angle triathlon bike you have a few options for cockpits. You can bolt a low profile aerobar directly to the stock 3T Ergonova drop bars as long as the bars are 31.8 mm clamp diameter and you clamp them close to the stem. The ergonomic shaping of the Ergonovas won’t let you clamp an aerobar on if it is more than 4 centimeters from the stem since the bar begins its ovalized, ergonomic shaping. If you go with this “semi-aero” cockpit it will be a quick conversion but you won’t have your shifters on your aero extensions and you’ll have to release your grip on the aerobars each time you shift which costs time.

Cervelo S1 2009

Cervelo S1 2009

The stock cockpit shown on the right, with a new aerodynamic triathlon cockpit installed on the right.

The best way to set up a nice aerodynamic frame like the S1 for triathlon/time trial specific use is to install an entirely new aero cockpit. If you cut all your control cable lengths in advance and do a careful job with your set-up and cable lengths this could be a 20 minute job changing cockpits if you are handy. We used the Visiontech aero wing shaped base bar and their excellent ski bend aerobar with Shimano Dura-Ace 10 Speed bar end shifters mounted in the tips of the aerobars.

If you decide to make a second triathlon specific cockpit for your S1 it will cost you the price of the Shimano Dura-Ace bar end shifters, the FSA VisionTech brake levers, base bars and aerobars (as our example used). You'll also likely want a cable set devoted exclusively to this cockpit for easy changes between the two configurations. Expect to spend about $350-400 for the components required to have a ready-made full aero cockpit. This is significantly less than considering the cost of even an entry level dedicated triathlon bike.

Once the cockpit is in place it is simply a matter of switching out the seatposts to the forward, steep angle triathlon configuration. We recommend paying for an additional seatpost permanently sized and set up in the forward, steep seat angle configuration to maintain repeatability in your position. Expect about $150-250 for your seatpost configuration including the cost of the new post and saddle. Now all you do is add your race wheels and you are ready.

Handling on the bike in both configurations is excellent, with the road handling being perhaps the most impressive. I had no issues with stability in the aero position or responsiveness in the road config. That means you could be attacking on the Wednesday ride, diving into a corner on the Saturday criterium and then setting a new time trial or triathlon P.R. on Sunday- if your legs can equal the capabilities of the bike. It isn’t difficult to make a bike stable or to make it responsive, but it is tricky to make it both and that is what Cervelo has achieved in the S1. It is effectively two bikes in one.

Cervelo S1 2009

The main triangle of the S1 features a sloping top tube which is an aerodynamic compromise but an ergonomic advantage for long torso riders.

There is an additional aspect to the usability of the S1, especially in the triathlon/aero cockpit configuration. Since the bike has a sloping top tube it provides additional stand-over height. This is very nice for long torso riders. The only flip side to this benefit is the sloping top tube is, by Cervelo’s own admission, not as aerodynamic as the parallel top tubes on their dedicated triathlon bikes like the P1, P2, P3 and P4. It is a small price to pay for a lot of versatility.

Other frame details include a very durable replaceable seatpost binder collar and 3T’s Funda aerodynamic carbon fiber fork. Being a dual use road and triathlon frame this bike has two bottle mounts in the traditional positions on the down tube and seat tube. The rear derailleur hanger is fully replaceable making this a very robust bike with Cervelo’s usual Lifetime warranty.

Cervelo S1 2009

Cervelo S1 2009

Additional main frame details include traditional dual bottle braze-ons on the down tube and the seat tube, unlike the triathlon specific P1 which only uses a single seat tube mount. The bulge chain stays and straight seat stays along with the proprietary chainstay bridge create a comfortable, stiff rear end that jumps when you do.

Interestingly, I liken the ride quality of the $2200 MSRP S1 to Cervelo’s pricey, ultra-lightweight stiffness to weight ratio carbon bikes. It is snappy and responsive and crosses bad pavement without excessive road shock. The seat stays are joined to the frame just below the top tube and may help disperse road shock while tightening up the rear triangle for lateral stiffness. It’s a nice combination of features at a reasonable price. I love riding this bike in both configurations. It is nimble and angry in the road configuration, and rides with calm authority in the aero configuration. This would be an ideal bike for very hilly triathlons where a traditional triathlon bike may not climb as well, especially out of the saddle. In that terrain you could simply leave the drop bars and STI levers in place since most of your shifting will be done on the climbs while gripping the top section of the drops, not the aerobar. Again, the possibilities on this bike make it very exciting as you contemplate different set ups for different terrain and race courses. The S1 is more than one bike; it is like a full race team kit of bikes.

Cervelo is one of very few companies to have a truly convertible geometry dual use bike that makes a nice road bike and a fine triathlon bike. Given the argument that the P1 can do double duty as two different bikes it is the thinking mans solution to the dilemma of buying two separate bikes for group rides and triathlons.

Cervelo S1 2009

Cervelo S1 2009

Versatility and subtle, advanced design features make the S1 a highly adaptable design that adds value by doing double duty as a dedicated road bike and fully functional triathlon bike with additional modifications. It may be the one bike you ever have to own for road and triathlon!


© Tom Demerly, Bikesport Inc.
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