Some of this may be obvious but here goes… Knee angle stays about the same for road and mtb. Generally, the rider is set up a little further aft (however you may measure that) than a road position. Reach is much shorter, and bar drop is far less aggressive; therefore, hip angle is more open. The key is allowing the rider to position themselves not only for climbing, but also for technical downhills where they may need to move their center of gravity off the back of the bike.
That’s all pretty general, but there are a few keys to keep in mind. Mountain Bikers experience many extremes during a ride or race, both in terrain and position on the bike. Cadence can vary substantially depending on terrain, and foot position through the pedal stroke will also tend to have more variability depending on the steepness of a climb. If a rider pushes his/her heel down more to power up a steep incline, than knee extension will increase as well. Of course, position on the saddle also varies more on an mtb both fore and aft; these extremes will also create different knee angles.
Whether or not you’re fitting a hardtail or full suspension bike must certainly be taken into consideration. A full suspension bike, depending on how active the suspension, will have a constantly changing saddle height and fore/aft position as the rear shock works through its stroke under power and over terrain. This, in turn, changes the rider’s position.
An mtb position is anything but static, and fitting in a controlled environment will simply not provide enough changes in position to mimic what a rider will experience on the trail. You have to prepare for less accuracy, and more of a general position, unless you go out in the field and work with an athlete in an mtb environment. It’s a little more trial and error.
In the past few years we’ve seen an explosion of mountain bikers coming in as the sport has seemingly “discovered” bike fit all of the sudden. A couple of things we’ve consistently learned and/or experienced. 1. Elite mtb’rs always want to try a lower bar position, but rarely stick with it; it simply does not allow for a good overall position for technical riding. 2. Measuring power while an athlete rides over a short pre-determined course over and over again can be beneficial as it allows you to track and evaluate positional changes. 3. It will likely take a few sessions to dial in an mtb position as the athlete rides with the new changes and assesses their effectiveness. 4. With this new interest for bike fit from the mtb community, getting experience fitting mtb’s is very beneficial for a fitter as very few understand it as well as road, tri, and tt. There isn’t as much data on the position, and most simply make general adjustments to position rather than try to find a truly optimized fit for their client. Hope that helps.
Jim Manton / ERO Sports
That’s all pretty general, but there are a few keys to keep in mind. Mountain Bikers experience many extremes during a ride or race, both in terrain and position on the bike. Cadence can vary substantially depending on terrain, and foot position through the pedal stroke will also tend to have more variability depending on the steepness of a climb. If a rider pushes his/her heel down more to power up a steep incline, than knee extension will increase as well. Of course, position on the saddle also varies more on an mtb both fore and aft; these extremes will also create different knee angles.
Whether or not you’re fitting a hardtail or full suspension bike must certainly be taken into consideration. A full suspension bike, depending on how active the suspension, will have a constantly changing saddle height and fore/aft position as the rear shock works through its stroke under power and over terrain. This, in turn, changes the rider’s position.
An mtb position is anything but static, and fitting in a controlled environment will simply not provide enough changes in position to mimic what a rider will experience on the trail. You have to prepare for less accuracy, and more of a general position, unless you go out in the field and work with an athlete in an mtb environment. It’s a little more trial and error.
In the past few years we’ve seen an explosion of mountain bikers coming in as the sport has seemingly “discovered” bike fit all of the sudden. A couple of things we’ve consistently learned and/or experienced. 1. Elite mtb’rs always want to try a lower bar position, but rarely stick with it; it simply does not allow for a good overall position for technical riding. 2. Measuring power while an athlete rides over a short pre-determined course over and over again can be beneficial as it allows you to track and evaluate positional changes. 3. It will likely take a few sessions to dial in an mtb position as the athlete rides with the new changes and assesses their effectiveness. 4. With this new interest for bike fit from the mtb community, getting experience fitting mtb’s is very beneficial for a fitter as very few understand it as well as road, tri, and tt. There isn’t as much data on the position, and most simply make general adjustments to position rather than try to find a truly optimized fit for their client. Hope that helps.
Jim Manton / ERO Sports