Photo gallery: Evelyn Stevens’ Specialized S-Works Shiv TT Hour Record bike
On Saturday, American Evelyn Stevens will attempt to topple Jeannie Longo’s “all-time hour record” mark of 48.159km — a high bar that still stands two decades after it was set. If she succeeds, she’ll also smash the 46.882km “unified: UCI Hour Record set by Bridie O’Donnell on January 22 in Adelaide, Australia, aboard a bike allowed under UCI standards for endurance track events.
Stevens (Boels Dolmans) has been putting in the training time with the aid of coach Neal Henderson, and so far, she looks to be on track to set her ambitious mark.
However cycling is still a sport of man and machine — or woman and machine, as the case may be — and Stevens and Henderson have been working closely with team sponsors Specialized, SRAM, and Zipp to fine-tune the second half of that equation.
At Stevens’ target speed of 48kph (29.825mph) in a covered, concrete velodrome, aerodynamics will play a major role.
She will ride the same Specialized S-Works Shiv TT frame she normally uses for time trials, though on a special “track prepped” version, running 53×14 gearing. The rear derailleur hanger has been cut off of the otherwise standard dropouts, and all of the extraneous ancillary bits such as brake bosses, cable routing ports, front derailleur tab, and bottle mounts have been shaved off and filled in.
To further highlight the significance of Stevens’ attempt, Specialized has also dressed the frame with a subtly customized paint job.
Zipp wheels are fitted at either end with a flat and narrow 900 disc up front and a wider, lens-shaped Super-9 disc in the back, the latter modified with two 5mm axle extensions to fit the road-standard 130mm rear dropouts.
Matching track-specific Specialized tubulars are used at either end, in a narrower 19mm front and 23mm rear width, both with 290TPI polycotton casings.
According to Specialized aerodynamicist Chris Yu, the decision to run with that staggered setup was based on wind tunnel testing at the company’s headquarters in Morgan Hill, California.
“For indoor velodrome tests, it’s basically zero degrees yaw,” Yu said. “When that happens, you just want enough [front] wheel width to support the tire width that you’re running. There’s really no reason to go wider than a [Zipp] 900 up front.”
“On the rear, it’s a little bit less of a concern either way, because it’s so well shielded — close to zero measurable difference among a lot of different setups. But we found that a little wider platform offers potentially lower rolling resistance. Especially on a track like Colorado Springs, where it’s not 100% perfectly smooth, that’s actually a potentially important factor. Even on a TT bike, there’s still a majority of weight on the rear wheel, so that’s where you’re going to get the most benefit out of optimizing that, especially when there’s zero aero penalty for doing so.”
Much of the wind-tunnel work has focused on Stevens’ position, which Henderson says is the “slipperiest” he’s ever seen of all the athletes he’s mentored — including Taylor Phinney and Rohan Dennis.
One of the results of that testing is her cockpit setup, which features a custom stem that allows more height separation between the base bar and extensions.
“It’s the same stem she uses on her TT bike,” said Henderson. “We do that because it allows us to use the bridge, which for her, optimizes her elbow position.”
“There are several ways with our hardware to get to those same touch points,” added Yu, “but for her position, we found that the optimum [aerodynamic] setup was to further separate the base bar and the pads.”
Other technical details include a full set of ceramic bearings, as well as a specially lubricated chain that was “run in” just once and will sit in a bag until Saturday. Total weight as pictured is 7.32kg (16.14lb).
As nice as it would be to break the UCI Hour Record, Henderson says his ultimate goal for Stevens is larger in scope: improving her performance in longer time trials, as that could have greater significance for her career, including this summer at the Olympic Games.
As a result, all of the critical elements of her setup are designed to be not only fully UCI-legal for time trial events, but also sponsor-correct.
“This hour record is preparation for Evie to be faster in time trials on the road — that’s goal number one,” Henderson said. “With that in mind, the fit and position should be virtually identical to the TT bike that she roads on the road. We also wanted everything to be team and sponsor approved. Are there maybe one or two track-specific pieces that might have been some margin better? I don’t know, because I didn’t test any, but I know that the setup we have is incredibly fast.”
Nevertheless, the world will have to wait to see if “incredibly fast” equates to “fast enough.”
Tune in to the Ella CyclingTips live stream of Stevens’ historic effort, which kicks off Saturday, February 27, at 12 p.m. MST / 8p.m. CET / 6a.m. AEST.