Longitudinal seal repairs sometimes tend to cause severe instability in motorcycles under dry conditions in corners. Anecdotally it does not appear to be strongly correlated to road temperature, although on days with higher than normal surface temperatures it does soften causing the front to slide. I am looking for cases where this was identified as a cause and low-cost solutions to improve the traction of these seal repairs
My hypothesis is that surface ripples cause the following problems and could be an underlying cause of many run-off-road crashes in rural areas:
- in the braking zone the suspension could pack down due to a lack of compression damping causing longer braking distances and hence higher entry speed
- a rider's arms could stiffen up due to excessive forces feeding through the suspension delaying the turn-in point and also slowing the rate of turn-in,
- at the apex the bike is easily destabilised that may cause a mid turn adjustment causing a wider exit radius to be followed,
- on the exit it could cause instability under acceleration causing the rear to lose traction.
I am looking for evidence where surface ripples are correlated to loss of control crashes, and whether this affects all types of motorcycle crashes, or mostly those types that have relatively poor handling attributes (i.e. Cruiser vs. Sportbike designs)
Hello Urie.
About the longitudinal seal repairs, I believe it may be related to the located loss of grip (maybe similar effect of road paintings).
Hi Urie. Empirical and personal experience with this, overbanding (the smooth tar bands used to seal tarmac cracks) and Rainurages, especially on French concrete motorways l(ongitudinal grooving of the road surface for rainwater management) are notorious for their negative effects on the handling of motorcycles. There are many data sets and accident analysis reports on road traffic accidents (RTAs) available, USA, Canada, UK, EU. To take overbanding first. The hazard is the reduced traction of the overbanding material compared to the road tarmac. In wet conditions it gets slippery. In dry hot conditions it melts. It was a problem in the UK leading to litigation after RTAs. The compounding of overbanding material was changed to include 2-4mm sharp abrasive grit to improve wet traction. In countries where hot dry conditions occur the overbanding can include more asphalt and less bituminous tar for better hot weather performance.
longitudinal grooves, aka rainurages, upset the dynamic stability of motorcycles and bicycles. Consequential crashes are then multifactorial. Catastrophic stability upset is just one cause, others will result from rider mis-actions as a result of less than catastrophic stability upsets.
There is little to no correlation to the type of vehicle, probably much correlation to the way the vehicle is ridden...
You have not mentioned a situation called "target fixation", the rider sees a hazard and looks at it in the process of riding. The consequence is that the vehicle steers towards the hazard. It is most often a failing of novice and improver riders. Experienced riders learn or are taught to "look at the part of the road they want to go up, not the thing they want to avoid!".
All of the hypothesis point you make are errors of low expertise on the part of the rider. A rider with high expertise will know either intuitively or as a result of training to excercise riding techniques to mitigate the risks you are interested in and have methods to manage situations as they develop.
Inappropriate use of speed probably covers most of the mishaps you wish to investigate.
i suggest you obtain a copy of Roadcraft, published by HMSO in the UK. It is used as the riding manual by The Institute of Advanced Motorists. It is available as an ebook. I am not connected in any way with any of these organisations. Regards. Jonathan. Motorcyclist for 40years.
Niraj is also looking at this: https://www.researchgate.net/post/Can_any_one_define_term_asphalt_mastic_Is_it_a_phenomenon_or_a_type_of_asphalt_which_has_flowing_consistency?tpr_view=0ZNKTlNfZMCR1wZr6pOLlQ1A2HBfRw606RRY_2
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