Motorcyclist Behaviour on Bends Figure 14. Average speed of riders on the 2nd and 4th right-hand bends across the two laps (with standard error bars added). doi:10.1371/journal.pone.0029978.g014 However, there was also an interaction between rider group 6 curve section (F(12,348) = 7.204; MSe = 3.890; p,0.001) illustrat- ed in Figure 15. Repeated contrasts revealed that this interaction occurred between sections 1 and 2 (p,0.05), 5 and 6 (p,0.05), and 6 and 7 (p,0.001). Simple main effects analysis showed that it was only the advanced riders who significantly changed lateral position between all adjacent sections (max. p,0.05). The novice riders significantly changed their lateral position between all adjacent sections from 1 to 6 (max. p,0.05), but did not significantly change lateral position between sections 6 and 7. In contrast, the experienced riders did not significantly change lateral position between sections 4 and 5, but significantly changed lateral position between all other adjacent sections (max. p,0.05). In section 1, the Figure 15. Mean lateral position for rider groups across the right-hand bends (with standard error bars). doi:10.1371/journal.pone.0029978.g015 advanced riders were significantly further away from the centre line than either the novice (p,0.01) and experienced riders (p,0.001). However, in sections 2, 3 and 4 the advanced riders no longer differed from the novice riders in terms of lateral position. Both groups however were still further away from the centre line than the experienced riders (for novice vs. experienced p,0.05; for advanced vs. experienced max. p,0.01). While the experienced riders continued to ride closest to the centre line in section 5, this was only significantly closer than the advanced riders (p,0.01). However in section 7, both the advanced and experienced riders were closer to the centre line than the novices (for novices vs. experienced p,0.01; for novices vs. advanced p,0.001). In summary, although the novices entered the bend closer to the centre line than the advanced riders, they made less rightward movement than the experienced or advanced riders between the first two bend sections. This means that by section 2, the novices were adopting a similar position to the advanced riders. Advanced riders tended to keep furthest from the centre line until the apex of the bend was passed, at which point they moved towards the centre line. Experienced riders reached this position much earlier having moved significantly towards the centre line before a line of sight was available to them. It appears that the experienced riders were favouring progression over visibility, whereas the advanced riders only positioned themselves for progression once they could see around the bend. There was also an interaction between bend 6 section (F(6,348) = 4.267; MSe = 1.262; p,0.001), which suggested that riders made an earlier, and more pronounced shift towards the centre line in Bend 4 than in Bend 2 (between sections 1 to 3). After the apex of the bend however, movement towards the centre line was shallower in Bend 4 than that noted in Bend 2. The final analysis of the right-hand non-hazard bends was concerned with the variance of lateral position. Although there were no main effects of rider group or bend, there was a significant interaction between the two (F(2,58) = 4.378; MSe = 0.408; p,0.05). In Bend 2 all riders varied their lateral position to a similar extent. Simple main effects analysis showed that there was PLoS ONE | www.plosone.org 12 January 2012 | Volume 7 | Issue 1 | e29978