Trade off

Just picked up the brand new car today...No it's not ours and will not be!
But driving it back home i noticed how the front suspension reacted to ruts in the road surface..and boy we in britian have plenty..our govenment seen's to like blowing holes in the afgan road's, rather than filling our's :!:
Anyway after some considerable "Bang's" i considered the poor damper system...on our be-loved Nortons.
Having the cope with such extreams, at 60 mph the front wheel is traveling at 1000/1 [one thousandth] of a second every 1 inch..yep 1000 th of a second for every inch :!:
So when the wheel drops into a pot hole at 60mph and the fork reacts by extending 1 inch ,then re-compress's 1 inch when it hits the pot hole far side..
well thats fast !
There is some factor's that cannot be transmitted into formula here,
So the issues are very complex to even consider, but the fact remains....forks under extream and sudden force have a lot to deal with.
Hydraulic lock up is a factor [with compression two-way damping], and moving the fork,wheel mass another.
Stiction is another problem , so the next time your wheel drops suddenly into a deep rut at speed ,just think how fast that was , 1000th of a second!..well almost. i think its 20 times faster than the engine valves open and close at 6000 rpm...maths experts welcome.
i

Aw shucks one pot hole in a row one inch deep ain't much a bother to forks but a series of em sure can be. Its bad juju to be braking much while engaging a road lip or dip. One interesting thing I got confirmation of from some crazy hooligan locals was if ya cross em fast enough you tend to skip over the lower peaks so only feel and have to deal with the bigger ones so rather smoother if more thrilling.

When experimenting with Peel fork fluid level, creeping up on it by 1/2 mile drive way test, got to the 190ish ml level felt great on the sharp impacts - for 1/4 mile then suddenly a bouncing bronco going opposite expected to fork action or road bounces, till I finished at 5 mph with Both feet dragging. Factory forks pump air out not uo for long.

Fork oil don't get that hot on hiways but can having a hi time off of it.

Thats what shim stack damping systems are good for. Im almost tempted to see if I can fit some DH MTB cartridges (888 RC3) into the old roadholders

Actually, the front wheel only falls into potholes at the speed of gravity. !!

Unless you are powering into a giant pothole, at your inch every 1000th of a second. !!??!!

No sir the fork springs will push the forks down into most holes way faster than gravity by pushing against the inertia of the bike mass and forward momentum. Its hard to wrap head around the measures but appreciate giving it some ball park numbers to write.

The bike mags have articles on the limiting factors in dampening capacity and reversals. There are 2 basic methods to dampen, one by tappered rod in a jet the other by valves and springs. The valves & springs take some time to reverse and control flows plus some time for some fork motion to occur before pressure changes conveyed to operate said valves. Electro ferro fluid will be the 3rd way when it comes on line but of course our wimpy chargers would not be able to power it.

Steve well said, if only gravity! it's that energy stored in the coiled wire..ready to be released, when there is suddenly nothing under the wheel....BANG :!: Air rifle's springs out poke gravity,even upwards!
Gravity is only 15ft per second,per second , 60mph =88 ft per second.
as steve say's go faster and the wheel skim's over the hole, it's passed over before the spring as "time" to even think about it..it's math's that need a formula behond me.
Spring energy [variable] over mass/frictional and hydraulic resistance x speed ..thats for starters...then tyre inflation and angle of attact...Better forget it and steer around the holes!
I read some where that British roads are costing the motorist millions in car repairs each year....also the speed humps cause more fuel to be used..well all that slowing down and speeding up ain't good fuel usage...the constant hammering must play havic with human organs, ? first to sue the highways will make them sit up. :lol:
I threatened to sue over the state of the road out side my house...it was so bad the house shook when lorries went past...the highways said it was the air pressure, i threatened to get some experts in...suddenly they spent over a million rebuilding it! and then suddernly the "Air pressure" went away.

You must have small potholes in your roads.
Or very long travel forks.....

The worst forks for off road is a toss up to me of long springers or factory bodged Roadholders. The worst cycles for off road is a toss up to me of hard tail chopper or sports bike. My next chopper will sport Girder single spring type not the dual row type.

Over decade ago we had discussion on suspension handling rough roads and Africa rental cars rules was brought up, renters told to keep speed up over 50 or so or the suspension and other parts broke in middle of nowhere. So either just creep along or grit teeth and hit with gusto~!

Here's article to keep some mental churning going on this subject.
http://www.modified.com/tech/0607_sccp_ ... ewall.html

LIkely only the likes of Ms Peel could power these babies w/o carrying a huge battery. My race level built Chevy cargo van and non race 4wd PU has inertial valves shock absorbers that work better that standard type I removed. I ain't looking for better forks anymore on Peel but may be after next Peel fielded.
http://www.cycleworld.com/2012/12/04/te ... irst-look/

Gravity is 32 ft/sec/sec.
Jaydee

john robert bould said:

Gravity is only 15ft per second,per second

Click to expand...

What planet (or large asteroid) are you living on.

I come in peace, take me to your leader :lol:

ggryder said:

john robert bould said:

Gravity is only 15ft per second,per second

Click to expand...

What planet (or large asteroid) are you living on.

Click to expand...

john robert bould said:

I come in peace, take me to your leader :lol:

Click to expand...

If you have calculated gravity as ' only 15ft per second,per second' then you are more likely to come in pieces.... !!?

Bear in mind that 32 ft/sec/sec is the ACCELERATION of gravity.
Soon adds up.
And if your front wheel springs down into a pothole, gravity dictates your bike will soon follow, it can't float along up there forever.
Or even for very long...

I had laugh one day when I was at an historic road race meeting. There was a little kid who was with his dad and somebody's 500cc manx norton. He yelled out 'dad, is this the the bike with the RS125 cartiridges in the forks?'

Can anyone describe what over and under dampening feels like on a cycle with the motions over whelm the dampening devices? The worst bouncing I run into are the 2ndary bridges in sweeping turns, I often get on pegs to let the bouncing occur easier and protect me tailbone and for sure slow enough not to find limits in that condition.

I think one of my straight line Gravel crashes on SuVee was the suspension packing up ie: being delayed enough it acted solid, when striking a series of pot holes in the shallow arc of a dip going 35, bike juddered as usual crossing holes but this time suddenly got smooth as it twisted horizontal on our CoG , rear swinging around to land tail first landing on me dragging me along a few yard up hill and strangely first thing that popped in mind was dang I did know there was a big cattle gate behind off the side brush I ended up in, then the pain and insanity of cycles hitting the bone registered. My thots just prior was how displined I'm being not taking any risks hot rodding THE Gravel.

I hit many yards of classic washboards but factory Cdo takes it fine, and I think my current one has lost fluid in RH leg.

Ok how far does a pebble dropped fall in 1/100 a sec?

hobot said:

Ok how far does a pebble dropped fall in 1/100 a sec?

Click to expand...

Have you ridden a bicycle Steve ?
As every cycle rider knows, gravity works very well, you feel every bump, pothole, pebble and GRAVEL !!

No need to get out the slide rule, calculator, acceleration graphs or fingers ...

Cheers.

2/100 inch.
Jaydee

Thanks for thinking this out for me jaydee. 1/100's of a second cycles lands in human sonic range. 2/100 of an inch is more like a tuning fork motion.

Rohan the most lasting visible scars on me are road rash from bicycle days and a favorite game of whole neighborhood was trying to make a 90's sideway corner
with a fire hydrant just a foot away at the ape, after we tossed white sugar sand on the smooth cement. So my bicycle expertise is crashing in more ways than you likely can imagine, as there was a old cherry hedge flush on inside of the side walk and game rule was each crash had to be left there for the next pilot to deal with, so kind of a card game luck of the draw. We did have to change one rule that required the pilot to stay where he landed, collected many living obstacles, but when my best friend ran right over me on purpose to win a round ... We started on steel clamp on roller skates so loosing traction is just part of having wheels underneath. Some my brain static remains from those days before helmets, just vasoline and rolled up blue jean with hole in knees.

Wes my buddy was a bicycle racer trainer and filled me in on how self ab-usage and nit picky they become to keep get the endophin high. Ugh not for me.

Don't avoid the issue - did you or did you not notice your front wheel floating in mid air a lot of the time, due to gravity ' not being fast enough' ?!!

I still have the scars on one elbow, where I couldn't avoid a house....

[video]http://www.youtube.com/watch?v=nPa1KrbiEZM&list=PLD41CECBDA5664881[/video]

[video]http://www.youtube.com/watch?v=If26-sZsgkU[/video]