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Old 09-05-2012, 12:53 AM   #802
640 Armageddon
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Joined: Mar 2009
Location: Greece
Oddometer: 1,797
That is indeed a great idea Paul ! Thumbs up for the quick response to this safety issue . I have no experience in injuring myself in the bloody thing (and I hope I will never have ) but it is indeed a major issue.

I think the concept is pretty neat. Nylon bolts is another food for thought, I was going that way when the safety issue came up. A Nylon bolt is strong enough both in shear and in tension to hold the assembly but you can choose the correct size so that if the load exceeds a certain value the bolts fail in shear. You just then replace the bolts. An M5 for example will break in shear using almost 100 kgs so I think it is doable ... (An M6 breaks at 180 kg in shear so I think this would be for quite a heavy person ) In the design that I am using, there is a third adjusting bolt which I plan to use as a crample zone if I may say. You can see here what I mean, I put the video before but jsut for reference

http://www.youtube.com/watch?v=Aavtn...3&feature=plcp


In all of the above, I think we have to take in to account the cabling. If anything breaks, for safety reasons, may be it is a good idea to make sure that the instruments auto-disconnect from the bike to prevent damage in the cables. It would not be nice for the tower to hang around from three/four cables when smashed around. In Paul's design this is not a problem but I am just mentioning it for other people who may go to the extreme of getting the tower of the bike Another idea (if you go to the extremes that is ... ) would be to put steel cables to hold the tower close to the bike in order not to load the cables. Much like they do in the F1 with the wheels so the wheel does not get apart from the car. Too complicated in my opinion

I dont know how all rally towers are attached, but I have a question. If the tower is only supported in one pivot point. Much like the one that you use to put the roadbook in the handlebars (sorry, I do not know if there is a name for it but I think you know what I am talking about). Even if you do not have a ''crample zone'' I think if you do not overtighten these bolts the thing will rotate upon impact. There is nothing to prevent it from doing so. Or am I missing something ? For sure it would be better to move out of the way but just questioning myself ....

The nice thing is that in almost any tower you can use materials to make it safer in case of impact with very little or no modification at all. It needs testing to get the tightening torques right so it slides, breaks etc with the correct load but that is why we are here

640 Armageddon screwed with this post 09-05-2012 at 01:13 AM
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