The new Cervélo S5 has been a terribly kept secret by the formerly Canadian company. The Jumbo-Visma pros have been riding, and winning, on this bike since the beginning of this season. Now, Cervélo, owned by the Dutch organization Pon Holdings, has made it official: its new aerodynamic road bike is here.
What took so long to release? Well, all the challenges that have been affecting bike production for the past couple of years. Cervélo wanted to make sure it had a bike in stock at launch.
Subtle but important changes to the (somewhat controversial) V power of the Cervélo S5
When the previous S5 was announced in 2018, it came with its head-turning and occasionally polarizing V-stem. The design served a few functions. It allowed the hydraulic brake hoses and shift cables to run inside from the bars, through the stem and into the head tube with fairly shallow bends. With a more conventional bar/stem combination, the cables have to make a fairly steep turn in the head tube. This curve can have a negative effect on mechanical shift performance. To make sure the mechanical shifting worked well, engineers like Scott Roy looked at the design of the V-stem. “The truth is, it was scary to make that stem,” says Roy. “It was kind of unexplored. We were going through testing and development. We even over-tested it. We had it with the team for a long time, but we needed to test it.”
The Cervélo S5 stem V. Image: Nick Iwanyshyn
The team nailed the functionality of the stem, but there was a problem with the fit. The bike came suddenly: great for the professional or vain, but impractical for most of us. Dealers had to have the proper bolts and spacers on hand to set up the bike for customers. If you bought a used S5, hope you have the same fit as the bike’s previous owner, or you’d have to hunt down the right bolts and spacers elsewhere. With the new S5, the bike ships with a set of bolts. and 30 mm spacers. It seems like a small thing, but it really makes things easier. When I assembled the bike, I simply put in all the split spacers, which fit around the brake lines, and turned the three screws. If I want to make a change, it will be easy.
The irony of the V-stem is that although it was first designed in part to ensure that mechanical shifting was smooth, this feature is no longer necessary. The new S5 frame is for electronic shifters only. The move makes sense, as high-end drivetrains are now very battery-centric. (Shimano’s line is electric up to 105 now.) Cervélo was able to redesign the S5 spokes and some other shapes because of electric-only drivetrain compatibility.
Whether you dig the S5’s V-stem or not, the company is behind it. It’s part of the bike’s identity. And, of course, it offers an aerodynamic advantage, which you’d expect from an aero road bike from Cervélo.
This Cervélo S5 features 30mm spacers: two 7.5mm wide spacers and three 5mm wide spacers. You can adjust the angle of the bars with the screws on the bottom. Image: Nick Iwanyshyn
More adjustable bars on the Cervélo S5, new seat post
The previous generation Cervélo S5 used wedges to adjust the tilt of the bars. On the new bars, you can simply loosen four screws, tilt the bars from zero to five degrees, and then adjust the fasteners.
Most new S5s come with a new seatpost with 15mm offset. This post replaces the 25mm offset of the previous generation of bikes. If you want a longer, more aggressive fit, you can still get the old post.
Another stab at the bayonet
The bayonet fork, with its “director” sitting in front of the head tube, is back. The old bayonet had an alloy cap that closed the fork around the head tube. (There is a tension rod inside to help with the connection.) Now there is no topper. The fork is a single piece. “We had originally tried to make a one-piece fork,” says Roy. “There were a few of us, constantly, in our downtime [after the 2018 launch of the S5], among other bike releases, echoing the idea of getting the one-piece fork. Manufacturing this new fork was quite difficult and it took a long time to figure out how to do it with the factory.
In some circles, the controversy followed the older S5. There were claims that the steering stop inside the head tube, which prevented the rods from turning too far to the left or right, could damage the head tube itself. Roy says he and his team tried to replicate the problem, but couldn’t. However, they have redesigned the stall. The old stop was a hard piece that butted against the inside of the head tube. The new setup includes a stop with rubber bumpers that face an alloy piece attached to the lower head tube.
The Cervélo S5 has a one-piece carbon bayonet front fork. Image: Nick Iwanyshyn The Cervélo S5 has clearance for 34mm wide tires. This tire is 28c. Image: Nick Iwanyshyn
Compensation triangles
For 2021, the UCI changed some of its rules regarding tube shapes and sizes on bikes. Remember, the UCI wants to keep the bikes looking bike-y, so it sets the parameters for various elements of the frame design. With the recent set of changes, the organization allowed the creation of compensation triangles in four places: between the top tube and the seat tube, between the bands and the seat tube, between the bands and the seat tube and between the down tube and the seat tube. The sides of these triangles that are next to a tube or stay can have a maximum length of 8 cm.
So what about these compensating triangles? They add more material that increases the surface area of the frame allowing for a greater sail effect as the bike moves down the road. The effect keeps the airflow connected to the frame at angles of guidance above zero degrees. Then it’s a bit like a sailboat that hides in the wind. In short, these little triangles, although small, improve the performance of the framework, making it faster.
On the new Cervélo S5, there is a compensation triangle between the top and the seat tube. Also, the material above the bottom bracket counts. While you can’t technically call it a triangle between the top, head and down tube (too many sides!), there are some of the same principles of offset triangles at work. The UCI says that from the front of the head tube—or in the case of the S5, the part of the bayonet fork in front of the head tube—to the open side of the, er, compensation quad, can be a maximum of 16 cm. The new Cervélo S5 is 10.5cm from the front of the bike to where the top/head/lower reinforcement area ends.
The company says it reduces drag on the bike by 65g.
One of the Cervélo S5’s compensation triangles is located between the top and the seat tube. Image: Nick Iwanyshyn The material between the seat and the down tube increases the aerodynamics of the Cervélo S5. Image: Nick Iwanyshyn
With all that new surface area on the frame, is it heavier?
Cervélo says that with the one-piece fork and some of the simplification achieved at the front, it was able to reduce the weight of the S5 by around 53g.
New Reserve 52/63 wheels
Pon Holdings’ family tree goes like this: The Dutch company acquired Cervélo in 2012 and Santa Cruz in 2015. Reserve wheels, which was founded by Santa Cruz engineers, was founded in 2014. It is also part of Pon. In 2020, Reserve launched its first road wheelset with the help of Cervélo. The Reserve/Cervélo collaboration continues with the new 52/63 wheels. These numbers indicate the depth of the rim: 63mm at the back, 52mm at the front.
(If you ask me, the deeper rear rim/deeper front rim you see on bikes chasing aero gains is more “mullet” than 27.5″ rear/29″ front mountain bikes. The haircut of mullet, or Longueuil coupe, has more hair in the back and is shorter in the front. A mountain bike with mixed wheels has more material (the metaphorical hair, if you will) in the front. Road wheels they have more material in the rear. And the mix of rim sizes in the front. Aero road bikes allow you to cut back on your overall times. For a MTB with mixed wheels, I suggest we call it A Flock of Seagulls. But I digress.)
Other dimensions include an internal rim width of 25.4mm and an external width of 34mm at the front. The rear has an inner rim width of 24.4mm. In general, the front edge is wider and shorter, while the back edge is narrower, higher and asymmetrical.
Not only did the engineers look at how the wheels performed when hit with laminar flow air—think smooth airflow hitting the front tire or head tube—they also looked at turbulent flow. They have plotted the turbulent flow intensities. Roy says Turbulent 1 is like gentle gusts in an open field. Turbulent 2 is stormier. Roys describes Turbulent 3 as Kona.
Roy and his team found that the wheel shapes performed well in both laminar and turbulent conditions. They were able to better identify and manage the stopping point on the front wheel. “A really good way to look at it,” says Roy, “is with a constant crosswind. With that crosswind, you correct yourself. You can feel the wind and adjust to it. What’s really good about these wheels is that when the wind drops, you’re not suddenly thrown to the side. Once the crosswind drops, you’re not thrown the other way. It’s a real smooth correction. The new wheels ride like less profile wheels deep in windy conditions.”
Rim shapes work best with 28c tires. The bike has 34mm step clearance.
Both Cervélo and wheelmaker Reserve collaborated on the new Reserve wheels. The rear has a rim depth of 63mm. The front is 52mm. Image: Nick Iwanyshyn
Cervélo S5 availability
Maria Benson, director of product management at Cervélo, says the new S5 is available now. If you can’t get your hands on one at launch, don’t worry. The company will have a second round of production and delivery in…