Chafing
Meld has been working on eliminating, or more accurately minimizing, the amount of chafing around the sitbone areas. We decided to write down a few of our thoughts based on our experiences.
Chafing is a result of friction wearing away the skin. Friction is always present, even when the skin is not yet worn and no discomfort is felt. With more time on the bike, there comes a tipping point when the skin breaks and we acutely and suddenly experience chafing. Since friction is always present, any action taken to reduce chafing needs to be employed before we experience discomfort.
The rate at which friction abrades a particular part of the body is dependent on several factors which are listed below. While one or more factors may (or appear to) be dominant, all contribute to friction.
Pressure distribution
Weight distributed over a smaller surface area results in greater pressure and thereby increased abrasion rate. A saddle surface that more closely resembles the body shape distributes weight and hence pressure more evenly.
Adopting different positions during a ride (e.g. upright on the tops versus hips rotated forward in the drops) places pressure on various parts of the body at different times. Correspondingly, overall abrasion experienced by any one part of the body is reduced.
Body surface closer to the saddle center experiences less movement relative to that further away (e.g. sitbone regions). Correspondingly, pressure placed closer to the center reduces friction. However, there is a limit as direct pressure on the perineum is not recommended.
Less relative movement between the body and saddle while pedaling can also result from increased saddle flexibility. A saddle shell that flexes with the moving body reduces the relative differences in shape at any one point in time and hence reduces relative motion.
Surface smoothness
The smoother the surfaces in contact with each other, the less friction experienced. Cycling shorts/bibs should have minimal seams. Additional, everyday clothing should not be worn underneath cycling shorts/bibs. Prior to and during a ride, check that the chamois does not bunch up and is correctly positioned (e.g. widest part of chamois should cover sitbones).
A common occurrence is the crystallization of sweat (salt) increasing friction. The hotter the weather, the longer the ride, the greater the salt buildup. Dressing appropriately for the weather and in layers (to accommodate changing temperatures) reduces excessive sweating. Chamois cream or body powder can help mitigate salt buildup. Having a change of shorts mid-ride (if possible) can also help.
Vertical friction management
While pedaling, two sets of surfaces move against each other: the body against the chamois/shorts, and the shorts against the saddle.
If friction between the shorts and saddle is minimal (e.g. smooth saddle surface), most of the relative movement between body and saddle is restricted to the shorts-saddle pair thereby reducing relative motion between body-chamois/shorts. Though beneficial friction reduction-wise, this may not always be possible due to the increased difficulty in maintaining a particular position on a smooth saddle.
What we can do
- Find a saddle with a shape that fits, and one that is flexible.
- Adjust the fore/aft position of the saddle, experiment sitting at different spots.
- Check seat height: an excessively high seat position results in side-to-side rocking of the hips increasing friction.
- Check the chamois: it should not be loose and move against the body while pedaling.
- Actively adopt different positions during a ride: upright on the tops while climbing, rotate hips forward while on the hoods/in the drops.
- Keep cycling shorts clean.
- Use chamois cream or body powder prior to hot/long rides.
- Use a saddle with a very smooth surface (downside: potentially reduced ability to stay seated at a particular spot on the saddle).
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