(By Michael Hanslip) from his own experience, good points
Speed & Efficiency
Many people associate wide rims with gravity oriented use. Cross-country riders may fear that the wide rim profile will increase rolling resistance by changing the tyre profile and how it sits on the trail.
To assess this, I did all of my hill work on the skinny wheels one week and then used the wider option for the following week. I used a power meter to keep my efforts consistent and a GPS to monitor my performance. For straight up climbing on a steep fire trail, there was no difference between the two setups.
For me the real test was putting them into action during a three-hour club race. I rode the first half on the event on the wide rims, then swapped to the skinny rims for the remainder. With the assistance of Strava and numerous pre-existing segments on the Mt Stromlo trails, I was able to assess the two wheels in climbing, descending, fast, slow, technical and smooth sections of the course.
Over time I got tired and my climbing speed decreased – I expected that – but there was also three really fun descents per lap with very little pedalling. In the end I was surprised to find no discernible difference based on wheel choice. Across a half-dozen timed sections (three flat and three descending) there was only one or two seconds’ difference between the segments with no pattern to suggest that either option was faster. The only variance was that I lost the front end and crashed during my first skinny-rim lap because the front tyre slid a bit more than I was used to with the wider wheels.
Prior to undertaking this test I assumed that one setup would be clearly superior in its performance against the clock. The reality is that even with GPS recording and power data there was no clear champion.
Of course for most of us, mountain biking is more about the experience than analysing Strava segments. In this regard the improved feel and feedback from the wider wheels would undoubtedly lead me in that direction. Add to this the ability to run lower tyre pressures for better traction and comfort without degrading the handling and I feel the wide rims stand as a clear winner. Knowing that there’s no real speed disadvantage only helps to cement this position. In fact there’s every chance that they may offer an against the clock advantage when faced with trails that are more technically demanding, as that’s where the traction and handling benefits are more likely to shine through.