Posted by David T. Ashley on April 9, 2010, 1:26 pm
> Re structural integrity - meaning the basic structure of the bike, now,
> not just whether the mirrors are fastened on tight - we're in general
> talking about things that really, really are pretty damned rugged and
> overbuilt for the purpose. It might be different if you were riding a
> custom bike that had been shaved of the last ounce of unnecessary
> weight, but the typical product coming off the line of the major
> manufacturers is a pretty solid piece of metal.
Hi Bob,
Primarily what I was looking for was some insight into whether there can
ever be invisible damage that will lead to structural failure. A lot of
unusual things could happen: for example, somebody could strike the bike in
a parking lot with a car, then pick it up out of guilt and never leave a
note or anything.
What I'm hearing is that they're pretty tough and there will nearly always
be some visible signs, such as crinkles near the steering tube that would
get caught next time I have a look, etc.
Next time I'm in the dealership I'll run the same questions by the service
techs who have done collision repairs.
Thanks, Dave.
Posted by Road Glidin' Don on April 9, 2010, 1:31 pm
> Next time I'm in the dealership I'll run the same questions by the service
> techs who have done collision repairs.
I'm guessing they have to stifle their laughter whenever they see you
approach.
Posted by David T. Ashley on April 9, 2010, 1:42 pm
> Next time I'm in the dealership I'll run the same questions by the service
> techs who have done collision repairs.
>I'm guessing they have to stifle their laughter whenever they see you
>approach.
To the best of my knowledge, that only happened once. That was when I rode
in for an oil change with a new rear axle and indicated to the mechanic that
he should replace it and give me the old one.
He is a young man (around 25, I think), and I could see the wheels turning
in his head as he struggled to phrase it delicately. When he handed the old
rear axle to me, he said something like "I'm pretty sure that you didn't
need to replace the rear axle".
The same axle is still in the motorcycle, by the way. I'm only on my second
rear axle.
: )
But yeah, it definitely happened once.
Dave.
Posted by The Older Gentleman on April 7, 2010, 3:29 pm
>
> First, what are motorcycle front ends stressed for?
Lots, but there's always a limit.
> What do you have to do
> to do damage? My common sense tells me that the activities listed above
> wouldn't do any damage because they don't generate as much stress as braking
> hard and/or hitting a pothole with the front wheel.
You'd be surprised. Minor frontal impacts... well, I remember riding
into the back of a car, decades ago, because I wasn't looking where I
was going. The back end of the bike pirouetted neatly upwards. No
visible damage to anything, but it popped both fork seals.
>
> Second, when is it wise to inspect things? How bad does it have to be
> before you'd want to look at things carefully?
Check after any impact. Properly.
>
> Third, what is the inspection protocol for front ends? What do you look
> for?
>
> Fourth, is it possible to have invisible damage where you have to remove the
> steering stem and have a look? Looking at the mechanical system, it looks
> like (because you have upper and lower bearings) that any overstressing
> would get the welds near the steering tube first, then the fork holders
> second, and that you wouldn't succeed in doing invisible damage internally
> where you had to tear things apart. What goes first? Can anything be
> invisible?
Steering head bearings go first. Forks second. Frames themselves are
surprisingly resilient. Steel frames can distort, but can be jigged back
into position. Alloy frames can crack and break. Beams can develop a
'wrinkle'.
A good check is the lock stops - people can straighten frames, replace
forks, but it's damn hard to repair damaged lock stops without it
showing.
--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
Posted by Rob Kleinschmidt on April 7, 2010, 4:36 pm
> 2006 Honda Shadow 600 ...
> The other day I was maneuvering the motorcycle at the gym (turning it around
> by forward-reverse-forward-reverse-repeat) and nearly ran into a brick wall
> going forward at maybe 1/2 MPH. I was on the brake at about the same time,
> so I stopped about 1 cm short. But I thought ... what if I had hit the
> wall?
> Other times I've been slow on the brakes and hit a parking stop (those silly
> cement things about 4-6 inches high) at well under 1 MPH. Essentially I was
> coming to a stop just as the front wheel touched.
> Other times I've taken the motorcycle over a curb by positioning the front
> wheel against the curb, standing on the pavement with my but off the seat,
> and then applying power and walking with the bike to get first the front
> wheel then the rear wheel over the curb.
> I was just curious about a few points ...
> First, what are motorcycle front ends stressed for? What do you have to do
> to do damage? My common sense tells me that the activities listed above
> wouldn't do any damage because they don't generate as much stress as braking
> hard and/or hitting a pothole with the front wheel.
You typically damage front ends by running into stuff
at speed. This is a bad riding habit to get into.
You will be able to tell when this happens because you
will notice the impact, the forks will no longer be straight,
the wheel will no longer be round and you will likely have
been catapulted over the front of the motorcycle.
Try to avoid doing this.
> Second, when is it wise to inspect things? How bad does it have to be
> before you'd want to look at things carefully?
Never ever hurts to inspect things.
> Third, what is the inspection protocol for front ends? What do you look
> for?
Look for escaping fork oil, looseness or binding in the steering
head bearings, non-smooth operation of the suspension and
blisters or bulges in the tire sidewalls.
> Fourth, is it possible to have invisible damage where you have to remove the
> steering stem and have a look? Looking at the mechanical system, it looks
> like (because you have upper and lower bearings) that any overstressing
> would get the welds near the steering tube first, then the fork holders
> second, and that you wouldn't succeed in doing invisible damage internally
> where you had to tear things apart.
For anybody else but you, I'd say there'd be noticeable
symptoms first.
> What goes first? Can anything be
> invisible?
Almost anything could go first, especially when the
damage is invisible. Beware the unknown evils lurking
in the heart of your motorcycle.
> Sooner or later I will bump something harder than I'd like ... so just
> curious.
When you do, if the worst you have to worry about is
the bike, consider yourself lucky.
> Thanks.
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> not just whether the mirrors are fastened on tight - we're in general
> talking about things that really, really are pretty damned rugged and
> overbuilt for the purpose. It might be different if you were riding a
> custom bike that had been shaved of the last ounce of unnecessary
> weight, but the typical product coming off the line of the major
> manufacturers is a pretty solid piece of metal.