Welcome to Pedal Science, the weekly bike fitting blog by Nick Thomas of The Endurance Coach. This week our resident bike fitter Nick Thomas discusses wheel choice.
One of the most effective ways of maximising performance is using an aero wheelset. Design varies considerably and all models have their pros and cons so it’s important to determine which wheelset is the most appropriate for their intended use. Factors to consider before buying new wheels include the following:
- What length of event will they be used for?
- Is the course flat and fast or hilly and twisty?
- How fast will I be riding?
The shorter the event the faster you’ll be riding. Aerodynamics become the primary consideration and comfort becomes less important.
Conversely for someone competing in longer events average speed will be lower and comfort becomes more important, especially if used for triathlon where the athlete needs to run immediately afterwards.
There are three main categories when choosing an aero wheelset:
- Aero spokes with conventional depth rims
- Aero spokes with deep section rims
- Disc wheels
For shorter events deep rimmed wheels provide improved aerodynamics. Depth of rim varies and there are several possible options depending on whether the wheels will be used over a variety of distances. A 40-60mm section will provide improved aerodynamics without being excessively heavy and won’t compromise climbing – this is the most popular option and proves to be very versatile on a variety of courses. 40-60mm also provides a safe, stable ride, something which can be compromised with deeper section wheels in windy conditions. If there are cross winds on the course, deep section wheels can be very unstable and riding the aero bars becomes difficult. In such conditions, any aero benefits are lost.
To gain the greatest speed advantage over shorter distances a disc wheel should be considered. Disc wheels provide a relatively harsh ride and although initially slow when accelerating out of corners (heavier wheels accelerate slowly), the gains are realised once the rider is up to full speed, as well as having superior aerodynamics the wheel gains considerable momentum at speed. For maximum effectiveness disc wheels should be used on fast, flat courses with minimal climbing or cornering (acceleration required). Disc wheels weigh more than standard wheels, which is why many people avoid them on all but the flattest courses, but by contrast, disc wheels are very stiff and flex very little, which means that when you're climbing out of the saddle, they do give a great deal of 'energy return' which can balance out the weight problem when going uphill. Many deep section wheels are known to 'flex' and when climbing, they can be heard rubbing the brake blocks. This flex is not an issue when riding on the flat in a straight line, but it is irritating when climbing!!
For most people competing in longer of hillier events the aerodynamic advantage of deep section wheels is largely irrelevant and can be a hindrance when climbing due to the added weight. Conventional wheels with aero spokes would therefore be the best compromise and generally provide a more comfortable ride. Price is also generally lower than deep section wheels so these wheels provide a cost-effective way to improve speed over a variety of courses.
Determine the type of event the wheels will be used for. The shorter the distance and greater the speed the more advantage you’ll gain by improving aerodynamics. For longer and/or hillier events you’ll be slower and therefore benefit more from a lighter, more comfortable wheel. The one thing which outweighs all of the facts and figures above, is that a disc wheel sounds awesome. For that reason alone it's worth the money.
Nick Thomas is the resident bike fitter at The Endurance Coach. He is a fully qualified bike fitter and expert in lower limb mechanics, holding a BSc (Hons) in podiatry. You can contact him using the email address: firstname.lastname@example.org or see more about his fitting services by GOING HERE.