Did you know that Best Bike Split was originally created specifically for time trial stages at the Tour de France? Well, it's initial idea was sparked by seeing a rider at the Tour many years ago that had a small piece of paper taped to his bike with the time trial course broken into specific pacing intervals. With the various factors at play, it's during these stages that World Tour teams rely on BBS data analysis to help evaluate and plan strategies for their riders. Stage 16 of the 2023 Tour de France offered a compelling case study of this, particularly regarding the decisions teams made about whether to implement a mid-race bike exchange (from time trial to road bike) and its impacts on the outcome.
In recent years, the Tour has incorporated more and more tactical time trials that test riders' abilities both on the flats and on steep gradients leading to the finish lines. These stages introduce an additional variable in equipment choice that adds complexity to stage preparation. Should a rider use a road bike, a time trial bike, a hybrid solution (seen mostly in earlier years), or attempt a risky bike exchange?
In Stage 16, the bike exchange gamble was first tested by Mikkel Bjerg, a rider from the UAE Team Emirates. Bjerg switched from his time trial bike to his road bike for the Côte de Domancy climb, a move that offered a glimpse into the team's strategy. It was soon confirmed that Tadej Pogačar, the team's leader and former Tour de France winner, would also switch bikes at the foot of this decisive climb.
Switching to a road bike before a climb can be advantageous, as road bikes are typically lighter and more maneuverable, which could theoretically allow a rider to gain time on a challenging climb like the Côte de Domancy. However, this decision also has its drawbacks. The swap itself consumes precious time, and a road bike may sacrifice aerodynamics, affecting speed on flat and downhill sections.
Using a Best Bike Split model of Stage 16, we can analyze these differences using our Time Analysis tool. The graph below is based on an estimated model of Pogačar's race, showing the impact of using a road bike over a TT bike for the final section of the course. The assumption is that Pogačar would be able to maintain 10 watts higher power and that his bike would be 0.7 kg lighter. The CdA should be similar for both bikes as he would be in a climbing position and not down in the aerobars.
Here we can see that given those assumptions, there are possible time gains on the steepest part of the hill. However, if we focus on our Time Delta metric, we can see that at most, the gain is 0.5 seconds per 100 meters, and once the road flattens out, the advantage is negated.
In total, we calculate that Pogačar saved roughly 7 seconds across the entire stage with the switch to a road bike over his TT. Unfortunately, the bike switch added approximately 11 seconds when considering the time lost to deceleration and acceleration required with the exchange.
A typical rule of thumb is if you can produce similar power numbers and stay aerodynamic over 22 km/h, there is still a small advantage to the TT bike even with a 1kg weight difference. The takeaway from this stage is not that a bike exchange is always a poor choice—in this case, it was basically a wash.
Try using the BBS Time Analysis Tool for yourself to answer "What If" scenarios and dive into this Stage 16 model here bestbikesplit.com/client/253284