The Tour de France’s eleven most marginal gains - The most comically minuscule upgrades on the world’s fastest bikes

Since the heady days of peak Team Sky, the phrase ‘marginal gains’ has become so commonplace as to almost be a mantra for the sport as a whole. New bikes come out every year promising measurable gains in aerodynamics, weight, and stiffness, and every year pro mechanics meticulously modify them, especially for the Tour de France. We’ve seen some expensive mods, like Lidl-Trek’s $1,300 hub upgrades for every bike to shave a few grams, but while my colleagues roamed the pits in Barcelona they saw some truly marginal, marginal gains.

You may find some of these laughable, but when stages are won and lost by millimetres, and the calorific savings of even tiny gains adding up massively over a three week race, I choose to marvel at the seemingly bottomless well of innovation that performance engineers seem to draw from, as well as what must be near infinite reserves of patience from the armies of team mechanics who have to implement these modifications. Without further ado, then, in no particular order…

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Tape over every bolt and void

Some bolts sit proud, some sit flush, and some are recessed. In all cases, though, there’s a little void into which your hex key or Torx bit goes, and the wind can eddy within these, ever so slightly increasing the system drag on the bike. Some are important due to being at the leading edge, such as the handlebar bolts on Jonas Vingegaard’s Cervélo S5, and others are important as they’re just big ol’ holes, like the hollow on the non-drive side of SRAM cranks.

If you’re going to tape one bolt though, you may as well do them all, and nobody does this quite like Visma-Lease a Bike, who even go so far as to tape over the adjustment bolts on the team’s seatposts. Tape, handily, doesn’t weigh much at all, so you can use it with gay abandon.

An aerodynamic bottom bracket

I’m sure, like me, you’ve spent hours staring down at your external bottom bracket cups just wishing they weren’t so damnably un-aero. UAE Team Emirates, or more specifically Tadej Pogačar, doesn’t have to stress about this as he has an aftermarket unit from Bikone fitted to his Colnago Y1Rs with a totally smooth non-drive side threaded cup to ‘save watts with every pedal stroke’ according to the brand, though it doesn’t say quite how many watts.

Considering that in order to remove the unit you need a special proprietary tool that tightens the cup from the drive side, it’s no wonder that only the team leaders get the unspecified wattage gains to go along with the 17g weight saving over the standard Bikone unit.

Special jockey wheel bolts

Pro cycling went through a phase where if you didn’t have an aftermarket rear derailleur cage with oversized pulley wheels, you may as well not turn up. The trouble with these massive sprockets is that they tended to weigh more, and at times they create something of a sponsorship clash. Now teams are looking to get their aero bikes down to the UCI weight limit rather than simply chasing every aero gain. Now, again at the UAE paddock, we’ve seen derailleur cages go on a diet, with the stock Dura-Ace retaining bolts for the jockey wheels being swapped out for aluminium ones.

Sadly, the CarbonTi website appears to be down, so for now the weight saving is unknown, but it’s good to see good old-fashioned weight weenieism alive and well.

Strips of coloured tape

No gram savings here, or ways to trick the wind. Lidl-Trek for the opening team time trial applied strips of different coloured tape down the sides of each rider's TT bike in an effort to reduce the cognitive load, and perhaps with a knock-on aero benefit too. If you’ve only got to think ‘I go in the line after I see yellow ’, you can glance across without really having to change your position at all and slot in when the colour is right. This is much easier than having to work out ‘is that Mattias Skjelmose’s lower leg spinning at 100rpm?’ Smart, and it builds on the Astana hack from 2025 where the riders wore different coloured gloves and aero socks.

DIY Aero derailleur

Is there no limit to the utility of black electrical tape? Not only can it be used to tape over every bolt and void on a bike, but it can also be used to tape over the lower portions of a Shimano derailleur cage to make a superlight aero hack, as we saw at the Ineos paddock. This must weigh a gram or two and save… well, who knows. Not a lot, but considering it costs pennies, you may as well do it, right?

Superlight bottle cages

For the last few years, the Elite Custom Race Plus was the king of the pro cycling bottle cage castle, partially because it’s good and also light, and partially because Elite sponsors many, many teams. Now, though, more and more riders are turning their backs on tradition and opting instead for the new Elite Leggero Carbon, tipping the scales at a mere 13g a piece; a 27g saving per cage which is on the cusp of being a maximal gain by the standards of this list. Pogačar himself even swaps his aero bottle cages on his Colnago Y1Rs for a set of these in his never-ending quest to keep his bike both aero and superlight.

Aftermarket thru-axles

Another quite un-glamourous part that’s been given the bling treatment at the UAE paddock is the humble thru-axle, which the team has swapped out for lightweight aluminium versions, again from CarbonTi, tipping the scales at a mere 31g for the rear of a Y1Rs.

Real weight weenies know that carbon thru-axles can be found, which weigh in the region of 30g for a pair, but we’re yet to see these be adopted anywhere yet, though it must be said the actual shaft could be made of cheese or spun sugar for all we’re usually able to see of it.

Lightweight disc rotor lockrings

While Lidl-Trek’s fancy hubs garnered a lot of attention, our eye was also drawn to one end of them where the standard disc rotor lockrings had been replaced by grey Tactic-branded units. These are ‘exceptionally light and strong’, and weigh a claimed 12.4 grams per pair; they are also machined from the same aerospace-grade aluminium as the hubs. There’s probably a handful of grams at play in swapping to these, and in all likelihood it’s probably as much an aesthetic or sponsor arrangement as an actual gain.

Old series Garmin

One thing that caught my eye while poring over images of Jonas Vingegaard’s Cervélo P5 time-trial bike was his choice of computer. Rather than the current small-but-premium Garmin Edge 550 that his team’s sponsor offers, he chose to run the smaller, older Garmin Edge 540. Given that for a time trial he was likely relying on a power number and perhaps a distance figure, the need for anything larger was likely surplus to requirement.

Aftermarket derailleur hanger

Derailleur hangers have two jobs: connect the rear derailleur to the frame, and in the event of a crash, they should bend or snap before the derailleur or frame does. Despite this, we’ve seen many iterations of upgraded hangers over the years, promising lower weight and crisper shifting, something that’s very hard to quantify.

These crop up on many pro bikes, but Pogačar seems to be the main culprit, with various coloured options depending on show at various points throughout the year.

Aerodynamic saddle

Yes, the thing that is almost entirely covered by your rear end for almost the entire time you’re riding your bike can be made aerodynamic, as evidenced by Jonas Vingegaard and his €490 Prologo Choice saddle, which is modular and features side vents for ‘unprecedented aerodynamic efficiency’. I’m not sure there was any precedent for aero saddles as yet, so Prologo is probably right in this regard, though actual wattage figures are hard to come by on the brand’s website.