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Original post deleted I guess - with no notice. Had a "naughty" word in title. To the mod who removed it - sorry - I was still shell-shocked when I wrote teh post and had to get moving.
Anyway - so I hop on my scoot to do some chores. I get on the main road, take a 20 mph turn a bit on the hot side get a block further down and it's "damn - forgot my meds". Since I was headed out to lunch and teh meds are taken with food - I figure I need to go back. So I u-turn at the next side street. As I'm making my u-turn the front end starts to go down and nothing I'm doing is stopping teh bike from dropping. So I stick out my left leg and start stopping - a real feat with a 545 lb bike. I mean the front end is doing some weird stuff and I'm freaking because the bike is going down and nothing is working! I notice vaguely the front end looks funny. I didn't go down completely but I now have a matching scratch on the left side and the handlebar end is scraped. But I did keep it from going down further - as I'm hauling the bike back up I notice the handlebars are skewed and the act of picking the bike up (still mounted using one leg and sheer arm power) is straightening the bars. what the hell I think. I get teh bike up and lock the front end. The handlebars are skewed a bit. I gotta tell ya - that scared the crap out of me. Apparently something has "let go" in the steering and the short turn radius was enough that the bars turned on me instead of turning teh front end. If that had happened when I sailed through that 20 mph turn....
Needless to say I rode like a grandma back home scared to turn. I'll call Chuck Monday to come pick it up.
Any clues what the hell could have happened? I'll take a peek tomorrow to see what I can see - I was too busy today.
Jon
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As long as both front wheels were doing the same thing then it is just the steering pinch-bolt that needs tightening a little bit (not much mind!). Not an uncommon effect if some toe-rag has tried to break the steering-lock at some stage - but otherwise down to duff PDI/service (rare).

If the wheels were doing different things check the steering-bar is connected to both wheel units... (I seriously doubt this is the problem. )
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I don't believe in coincidences...is there a chance something came loose when it went down at the Dragon? Just me thinking out loud, but I wonder if something coulda jarred/bent and its been waiting for a certain type of turn(the U turn or the 20 mph turn) to bring it out...dunno. Let us all know what Chuck can figure out...I too would like to keep an eye out.
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A relatively big 'bang' on the bars could easily do it. Just by forcing the bars around the steering-head a tiny bit the head gets scored slightly and the bars aren't so tightly bound to them.

BTW the torque setting in the manual is a guide - make sure that the pinch-bolt is done up to at least that torque, then check the bars won't move against the wheel's direction. A gentle 'bang' against the steering end-stop should result in no movement. (A hard one should, but that means re-tightening...)
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The steering stem must always be firmly tightened
I have "crossed swords" with jimc on this matter on several occasions and will continue to do so until he stops giving misleading and dangerous information.

It is dangerous to "loosely" tighten the steering stem in case you forget to undo the steering lock, and thus break the lock off.

The correct procedure for this type of steering clamp is to ensure that it is very tight, so tight that when holding the front wheels against the steering stop on either side, you cannot move the handlebars at all while applying a reasonable amount of turning force to them.

It is also important not to apply a ridiculous amount of tightening torque to the pinch bolt, in case you crush the stem.

Above all, it is important to regularly check, by trying to turn the wheels past the steering stop (or by holding them in some other way, such as between your legs) to make sure that the handlebar assembly does NOT rotate on the steering stem.

If you can move/twist the handlebars at all with the wheels held firmly, the clamp is too loose.

This is an important safety issue and needs to be checked/clarified in this way, as the OP's experience has shown.

A broken steering lock is unlikely to be fatal, or even lead to any sort of injury. On the other hand a loose handlebar clamp at any sort of speed is quite likely to be painful or even deadly.

Respectfully

Trevor G
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The torque specified in the manual is designed to prevent the steering-lock being broken, while ensuring the bars can never move wrt the wheels in normal use. I think we are at least half-way in agreement...

It is one reason why Piaggio bikes get stolen by potential joy-riders less than many others.
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jimc wrote:
The torque specified in the manual is designed to prevent the steering-lock being broken, while ensuring the bars can never move wrt the wheels in normal use. I think we are at least half-way in agreement...

It is one reason why Piaggio bikes get stolen by potential joy-riders less than many others.
You have to be joking, or just plain technically ignorant to repeat something as crass as that, in a real-life safety situation.

You provide a lot of good information, but without a technical background you are unable to discern fact from claptrap.

This is at least the third such post (where a rider has gone down or nearly so, due to a loose handlebar clamp) I have read (there may be more, I don't monitor this site continually) and it is time that the need to correctly tension the handlebar clamp and recheck this as a matter of course, becomes a sticky.

We usually don't get to talk to the rider after a fatal accident, so there is no way of telling at this stage whether this problem has ever had really serious consequences. Unless people are warned, it's only a matter of time.

Because of the two front wheels there is more force being applied all the time, both to loosen the joint surface and to overcome the tension of the clamp.

I imagine that there are not too many other Piaggio vehicles with this steering arrangement (the handlebars clamped to a steering tube) and if there are, none with similar weight or stresses on the front as the MP3.

Respectfully

Trevor G

PS I have the pleasure of owning and riding a number of Puch scooters from the 60s which used this same arrangement of clamping the handlebar assembly to the steerer.

I would never commence a ride without checking the tightness of the clamp in the manner shown in the previous post. The clamp can "become" too loose at any time.
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Trevor_G wrote:
jimc wrote:
The torque specified in the manual is designed to prevent the steering-lock being broken, while ensuring the bars can never move wrt the wheels in normal use. I think we are at least half-way in agreement...

It is one reason why Piaggio bikes get stolen by potential joy-riders less than many others.
You have to be joking, or just plain technically ignorant to repeat something as crass as that, in a real-life safety situation.

You provide a lot of good information, but without a technical background you are unable to discern fact from claptrap.

This is at least the third such post (where a rider has gone down or nearly so, due to a loose handlebar clamp) I have read (there may be more, I don't monitor this site continually) and it is time that the need to correctly tension the handlebar clamp and recheck this as a matter of course, becomes a sticky.
I entirely agree. Why you think I do not I do not know. Please re-read what I wrote and point out the bit you think is wrong, rather than damning all of it.
Quote:
We usually don't get to talk to the rider after a fatal accident, so there is no way of telling at this stage whether this problem has ever had really serious consequences. Unless people are warned, it's only a matter of time.

Because of the two front wheels there is more force being applied all the time, both to loosen the joint surface and to overcome the tension of the clamp.

I imagine that there are not too many other Piaggio vehicles with this steering arrangement (the handlebars clamped to a steering tube) and if there are, none with similar weight or stresses on the front as the MP3.
Every other Piaggio bike that I know of has the same pinch-bolt arrangement.
Quote:
Respectfully

Trevor G

PS I have the pleasure of owning and riding a number of Puch scooters from the 60s which used this same arrangement of clamping the handlebar assembly to the steerer.

I would never commence a ride without checking the tightness of the clamp in the manner shown in the previous post. The clamp can "become" too loose at any time.
Never commence a ride without checking the steering-clamp? With all the other things that would be more likely to need attention, I'm surprised you found time to ride.

Respectfully...
OP
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jimc wrote:
A relatively big 'bang' on the bars could easily do it. Just by forcing the bars around the steering-head a tiny bit the head gets scored slightly and the bars aren't so tightly bound to them.

BTW the torque setting in the manual is a guide - make sure that the pinch-bolt is done up to at least that torque, then check the bars won't move against the wheel's direction. A gentle 'bang' against the steering end-stop should result in no movement. (A hard one should, but that means re-tightening...)
Nope - not what I would consider a big bang - consisdering of course that supporting teh weight of teh 500 on the handlebar end is going to create some stress. But I rode it all the way back home with no issues and we were doing the twisties and also a few tight turns in the parking lots and such. This was literally after a week and quite suddenly. Very bizarre feeling to turn and nothing happens - it's almost like gravity went odd or something. I will get out and check the clamp - first gotta find user manual...
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If the handle-bar took the weight of the bike while on the ground it could have been moved wrt the wheels - this would be a far larger stress than it normally encounters. The worrying bit is that it went back so easily! Get that pinch-bolt torqued up and tightness checked, as you don't want it happening if you hit some stone or kerb obliquely. Trevor's dead right when he says it's a safety issue. (Not about the steering-lock though - it's a sales point!)
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jimc wrote:
If the handle-bar took the weight of the bike while on the ground it could have been moved wrt the wheels - this would be a far larger stress than it normally encounters. The worrying bit is that it went back so easily! Get that pinch-bolt torqued up and tightness checked, as you don't want it happening if you hit some stone or kerb obliquely. Trevor's dead right when he says it's a safety issue. (Not about the steering-lock though - it's a sales point!)
Looking at the torque specs it says 50-55 Newton/meters - isn't that about 12 ft/lbs? I'm assuming the adjustment is the clamp under the steering cover..
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50-55Nm ~= 36-40lbft. Quite tight! There's a notch at the 6 o'clock position in both the steering tube and the clamping ring, it's set up right if these are aligned.
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jimc wrote:
50-55Nm ~= 36-40lbft. Quite tight! There's a notch at the 6 o'clock position in both the steering tube and the clamping ring, it's set up right if these are aligned.
Now that's a handy tip - I hadn't looked back there yet and was in fact wondering if there were an alignment mechanism. The handle bars were not what I would call real loose but in fact I could (and did) wrestle them around using just my arms and the suspension limits. I have no idea why they let go in a tight turn as it seems I really had to exert some pressure to get it to slip but perhaps I'm simply not fully appreciative of how much vector torque is generated in that type of turn. I will see if I can find my old "needle" torque wrench to see what it is at before I tighten it - my normal wrench is a calibrated micrometer click type - not useful for reading current torque.
Thanks,
Jon
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jimc wrote:
50-55Nm ~= 36-40lbft. Quite tight! There's a notch at the 6 o'clock position in both the steering tube and the clamping ring, it's set up right if these are aligned.
Even though there is a notch, there are what translates to several degrees of possible "play" in either direction...exactly why it's important to torque the pinchbolt securely.
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Sorry, didn't understand that. Re-phrase perhaps?
OP
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jimc wrote:
Sorry, didn't understand that. Re-phrase perhaps?
Sorry for delay - had choes to run - I see a notch in the tube and something that appears to be a tab on the bars - the tab being a bit wider than the notch - just center these two?
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Harumph... Yes, I suspect. Pictures? There may be differences.
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jimc wrote:
50-55Nm ~= 36-40lbft. Quite tight! There's a notch at the 6 o'clock position in both the steering tube and the clamping ring, it's set up right if these are aligned.
Hmmm - the weird news is that the steering appears to have been tightened to spec - it did move a tad it seems - perhaps not. Increased torque to 50 lbft. *sigh* to the shop she goes - I do feel better about riding her there tho.... maybe go ahead and get the 3,000 checkup out of the way...

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