Crash bars and the CHiP flip

[tibork]

Wow! As an owner of an '94 R1100RS for several years (first BMW bike) I always envied the RT owners with the rear crash bars as I thought if you go down you have your side cases and probably your motorcycle as a whole better protected. For years I searched for something like those for the RSs, even asked other RS owners but my searches turned up with no results at all. I was disappointed about it until just recently when my wife and I started to watch the old CHiPs shows (TV show from the 1970s) as a relaxation in the evenings and witnessed the downfall of those crash bars. In these shows they use the Kawasaki KZ 900s and 1000s with full police dress up including front and rear crash bars (image below). The first incident came in a scene where a stunt man had to drop one of these bikes, he properly turned 90 degrees and quick put the bike down on its side and let it go. To my surprise the bike only slid for a second, then due to most of the weight on the bottom started to stand back up but only till the wheels hit the pavement again which sent the bike into a complete tumble, flipping over and over until coming to a stop and completely destroyed. Then a few episodes later same scenario happened, stunt man drops the bike, however this time even he was on the pavement already his lower leg was still over the seat when the wheels again hit the pavement, the bike flipped again this time sending the stuntman into the air and a couple of seconds later he landed in and awkward upside down position. Lucky for him he was kind of thrown to the side because again this bike too went into tumbling on a straight path, flipping over and over until coming to a stop completely destroyed.

So now I am questioning the true value of those rear crash bars and at this point kind of happy not to have them, I rather scrape some parts than total my bike and possibly get hurt even worse. I do have front engine guards which protected my bike but just from a short slide when my clutch broke on the highway at 70 MPH and I was able to shift down and get off at a ramp but at the end of the ramp I just could not shift down from 2nd to neutral making me drop the bike but at a slow speed for fortunately.

Any similar experiences by anyone equipped with rear crash bars? I did read an RT owner's story a while ago where he fell with his bike but his bike stood completely back up and continued down the road until it went off and stopped and went down again in the grass.

 

[bobs_one]

I suspect that it's just physics and luck and not due to the rear crash bars.

Many years ago I was riding a Honda 750K and made a right turn over a region of the road which was covered in motor oil. (Turned out the city works empoyee who was spraying the dirt shoulder with used motor oil to keep the dust down - remember those days!? - hadn't turned off the spray when he drove through the intersection).

The bike and I low sided and the bike was 90 degrees to the direction of travel. It slid down the road for a ways (leaving me behind) and then the tires "dug in" and the bike flipped up into the air (quite high) and landed on its other side (in several pieces, sigh). The bike did not have crash bars.

Beleive it or not, a couple of years later, riding a goldwing with both front and rear crash bars, I had a similar thing happen when I hit a puddle of motor oil in the middel of the road (apparently a car had had a major engine failure on the road) and the bike (and I) did a low side. The bike slid down the road on its side but the tires did NOT dig in and the bike did not flip.

I'm not sure that there is any link between crash bars and flipping (and I think those kawasakis are more top heavy than boxer engined bikes - which may be the real difference here)

In the past, I've seen people offer up this "increased tendency to flip" as an attack on boxer engines - because the cyclinders keep the bike more upright so the tires can dig in - I think the lower center of gravity actually counters this argument.

 

[pglaves]

If a bike, sliding on its side, continues to slide without the tires returning to contact with the pavement it is unlikely to flip/highside. However, if while sliding the tires do make contact with the pavement that might upright the bike and cause it to flip.

So the question is whether a given configuration may cause the sliding bike to have the tires return to pavement contact. Boxer cylinders may contribute. Hard bags may contribute. Protection bars may contribute. Gravity pockets may contribute.

 

[cajunrider]

Crash bars, front AND/OR back, are only good for slow speed tip-overs. Fortunately, this is where most accidents happen, so the bars usually do a decent job of protecting the bike. If you go down at any kind of speed, however, crash bars are not going to help. That 1" or 1 1/8" bar is not going to hold up to a LARGE impact.

I've even seen a crash where the crash bars themselves bend in enough to poke a hole in the engine case. That bike would have been better off without the crash bars. A new tank is cheaper than a new engine!!

My Triumph's main frame spread out upon impact, breaking the engine mounts clean off the engine... I was going about 25 MPH. No crash bar on the plant would have stopped that... the frame itself gave away.

Bottom line... crash protection is only good for slow speed stuff. Once you're above a certain speed (maybe 20 or 30 MPH), it's sheer luck for the bike to survive.