Making some smart changes to your bike’s set-up could have you saving some serious watts.
The benefit of aerodynamically optimising your bike and equipment is well documented, deep-section wheels, aero frames and super-tight clothing all undoubtedly help to make you faster on the bike. There is, however, another element of the equation that riders are quick to overlook and neglect that could be worth a serious amount of Watts.
Frictional losses in general, including rolling resistance, are the second biggest factor after aerodynamics that dictate how fast you can ride for a given output. Although individually optimising each specific area of frictional loss might not be significant, as a total package there are real savings to be had.
From tyre configuration to bearings, there are ways to reduce friction to give you the edge come race day. If you are looking to be at the pointy end of the competition you cannot afford to overlook the advantage that friction reduction can serve. Here, we look at the top four ways in which you can minimise the watts you are giving away to friction.
1. Waxed Chains
There is a lot of hype around the use of waxed chain treatments in the world of cycling right now. A quick chat with anyone at the start of the race will reveal that those who are looking to make every efficiency saving possible will be waxing their chain.
Chain wax replaces the more typical oil-based lubricant and instead uses a paraffin-based wax that in more premium products also includes additives such as molybdenum disulfide and polytetrafluoroethylene (PTFE). There are numerous benefits to waxed chains when compared to oil-lubricated chains. As the wax treatment dries and solidifies it is less impervious to attracting debris that will introduce friction and act as a grinding paste.
The real benefit of chain waxing comes from the addition of the PTFE and molybdenum disulfide. These additives actually make the surface of the chain smoother which results in a decrease in experienced friction. If you were to look at the surface of a clean, unlubricated chain under a microscope you would find that it is full of small undulation and imperfections. As the chain interacts with the teeth of the cassette and chainring these imperfections can increase the amount of energy it takes to slide over the interfacing surfaces. What the molybdenum disulfide does is it smooths over these imperfections making the surfaces of the chain links and rollers able to glide over one another with less required energy. It is much the same as trying to push something along a carpeted floor versus an ice rink, it is much easier to move things when the surface friction is reduced.
Moving over to a chain waxing programme is a relatively involved process as it requires the chain to be completely degreased before applying the wax which typically has to be melted down and applied in a hot bath. For those with the patience to add this to their bike maintenance routine, the reward can be between 6-8 watts over oil-based lubricants. For a rider with a 300-watt FTP that is almost a 3% saving.
2. Premium Bearings
Another area that can yield instant and tangible benefits is investing in upgrading the bearings that your bike rolls on. Bearings are everywhere on your bike, they are in your hubs, bottom brackets, pulley wheels and steering. Any resistance within the bearing itself is going to result in an efficiency loss due to bearing friction.
Typically the bearings that come as standard with most bikes will be a simple steel or stainless steel bearing. This means that the small ball bearings that roll inside the races are made of steel. Over time these can corrode, pit or score meaning that there is a gradual degradation in performance with more and more friction being introduced.
Upgrading to ceramic bearings is a surefire way to reduce the rolling friction of your bike. Replacing standard bearings with ceramic ones much like Eenox’s LS-10 range will reduce the rolling resistance of the wheel at the hub. The LS-10 range pairs a high carbon steel race with ceramic ball bearings which exploit the best qualities of ceramic as a bearing material. When compared to steel ball bearings, ceramic bearings are far harder to wear and are stiffer meaning that they retain their shape and therefore minimal contact patch for a considerably longer time. This results in a more energy-efficient bearing with far less energy being lost as a result of friction.
Something that is recommended with the use of ceramic bearings is regular maintenance, as the ball bearings are so hard-wearing it is important to keep them well lubricated and clean. Eenox offers both a race day specific and everyday grease to help keep their bearings rolling in top condition.
Making the switch from standard steel to ceramic wheel bearings can net a saving of up to 8 watts which is not an insignificant amount.
3. Think About Chain Line
Gearing is an important part of the equation when it comes to minimising frictional loss of a bike's drivetrain. A bike's drivetrain is most efficient when the chain travels in a perfectly straight line from the chainring to the cassette. As soon as the chain starts to deviate from this straight line you are introducing additional friction into the system. Of course, this cannot be avoided and is part and parcel of having a range of gears at your disposal.
There is, however, something that you can do to help minimise chain deflection at the points it matters most. Choosing your gearing correctly will allow you to ride in a gear combination that results in the least chain deflection from chainring to cassette. For a 12-speed system using a double chainring setup the most efficient sprocket to be in whilst riding in the big chainring is somewhere around the 8th or 9th sprocket however it is easy to assess this by eye. When you have worked out what sprocket is your most efficient it is time to do a bit of maths to calculate your optimal chainring size.
If you know roughly the speed you anticipate spending the majority of a race or time trial at and you know your preferred cadence range then you can calculate what chainring will facilitate this. An online calculator such as bikecalc.com will allow you to put in all the relevant information to make things a bit simpler.
We are seeing more and more professional riders look to this strategy, specifically in time trials to save crucial watts simply by optimising their chainline. In the worst case, frictional losses due to chain deflection (cross-chaining) can amount to around 5 watts.
4. Over-Sized Pulley Wheels
This is worth investing in if you are looking to save every last watt ahead of that key race on the calendar. Although most oversized pulley wheels will come with ceramic bearings as standard it is not actually this that presents the notable saving. Instead, it is the larger diameter pulley wheel design itself.
By having a larger pulley wheel the angle the chain has to deflect to navigate through the rear derailleur and onto the cassette is reduced. This reduction in deflection means that the chain links are bending less which means that the links are rubbing against each other less resulting in less friction in the system.
The exact figure for how many watts can be saved is open to debate but the general consensus is that it sits around 2-4 watts when compared to a standard set of stock pulley wheels.
Savings Not To Be Sniffed At
In the four areas detailed above, there is the potential to save up to 25 watts by optimising your bike by reducing friction in key areas. For reference, a set of deep-section carbon wheels offers around a 20-watt saving when compared to standard aluminium rims. When put in this context investing in reducing the system friction of your bike is a worthy investment of both time and money.
About The Author
Alex Hunt, Cycling Tech Writer
Alex loves all facets of the cycling world with a particular interest in cross country mountain biking and big adventure rides. He is a mountain bike coach and guide in the Forest of Dean.
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