I just came back from Inzane VIII, a national event of the VRCC. A vendor is selling 6 degree raked triple trees for the Valk. He's claiming easier steering, blah, blah, etc. These trees are going on TWO wheel riding Valks. I discussed the safety issue with him for some time. He says no problem as long as you watch certain parameters, such as proper tire inflation, proper relationship on suspension front and back, etc.
A friend of mine who liked the looks of my 4.5 degree raked Valk with sidecar (Cool, he thought), had the 6 degree triple tree installed by this vendor about 2 months ago.. About three weeks ago, he accelerated to 100mph to keep up with his buddy and went into a full lock to lock high speed wobble from which he almost didn't recover. In his words, he hadn't checked the front tire pressure on his Valk and the pressure was about 18 pounds instead of the normal 40 pounds. Now this guy isn't much up on maintenace or tire checking and the triple tree vendor told him that was what caused it. It seems to me the tolerance for error is extremely narrow now that the trail is reduced. A reduced trail like this on a two wheeled Valk is , in my mind, extremely dangerous, especially with a rider where appearance is everything but who is very casual on maintenance. Any comments?
Wayne
Bet your buddy starts checking his tire pressure now!
=8^0
But seriously - this is what can happen when folks make changes to steering geometry based on looks instead of function. Performance modifications work both ways!
I think on this site you will find most will say not to operate th ebike as a solo once trail is reduced. This is by far the safer policy on all fronts. Can it be done? Sure in some cases dependant upon how much the trail was reduced and how it was done. Steering head angles come into play as well as other factors like you mentioned. Again, the best policy is to get trail reduced to ease steering on a sidecar rig or trike and not just for looks on a solo bike.
Sometimes I wonder how any of us survived the 60's when were were altering steering heads to look cool and lower the front of the bike that was getting a long front end installed while knowing zero about steering geometry. Lonnie. were you there? LOL
Remember ..."WHEN RIDING GETS SERIOUS LOOKS MEAN LITTLE" 🙂
I once had to ride my bike that's set-up for hack work (LL's + car tyre's), 15 mile's to put a sidecar on. It was the most frightening thing I have ever experienced on a motorbike. I mean I had to steer it upright and could'nt go more than 10 mph with both feet down. If you want an adrenalin high, forget bungee jumping, just take you're sidecar off a dedicated hack hauler and ride it round the neighbourhood solo.
Safe riding Karl.
This is one of the biggest reasons I dislike altering the triple tree. If you should decide to sell the rig, even if you make the new owner aware of the change, there is no guarantee that he won't split it and sell the bike separately without mentioning the change. Someone down the road could die as a result of your action. A Leading Link is so obviously different than a stock fork that questions would arise. In most cases, a modified tree is unnoticeable unless the bike happens to be setting next to an identical model.
Likewise, you no longer have the option of selling the bike and keeping your sidecar without spending money on replacing the tree. With an LL, you drop the tubes, slide in the originals, and hook up the brake.
I'm fortunate in that I still have my standard triple tree. I can sell my rig or separate the motorcycle and put the standard tree back on and maybe sell the 4.5 degree tree. I got a good deal on the 4.5 degree tree.
You're absolutely right about the risks involved. If I sold the rig, I'd probably put the standard tree back on then wait for the new owner to want it to steer easier. "Such a deal"
I think his bike was trying to tell him something. He might want to listen.
Your friend is not alone and is lucky he did not wreck.
In 1974, while in Germany, I witnessed a 750 honda "chopper" throw it's rider at roughly 110 mph on a smooth straight section of road. I was following in traffic on my bike as these two riders drag raced off the light. Everything was going fine and suddenly the Honda became a blur and the rider was pitched off to one side. When he came off the bike he was thrown through the air several feet to the left of the bike. He continued to tumble on his hands and knees for quite a ways down the road as traffic scrambled to avoid him.
He was not seriously injured, but had was off work for a few weeks due to road rash.
I talked to the rider when I recognized him days later at the hospital. We were both military at the time.
His brother and he had taken the remains of the bike apart looking for the cause.
The bike had raked triple trees combined with a extended square tube telescoping front end. Everything was new and properly installed.
The lower leg bushings had excess free play from the manufacturer. That apparently started the wobble. When he attempted to stop the wobble by brute force, he lost the leverage game because of the lack of trail and was pitched off the bike.
Her is another issue to consider on a bike with a telescopic fork. When you panic stop a motorcycle using the front brake, as the front fork compresses and the rear fork extends, it greatly reduces the trail of the bike. On a bike reconfigured as your friend has done, he might not have any trail or even negative trail during a quick stop.
Should he lock either wheel and loose the centrifugal force generated by it, he will go down. It happens to GP racers all the time. If he wants that cool look changing the neck rake on the frame will give him what he wants. If he really wants the raked look in a stock motorcycle, HD makes the V rod that uses an excessive neck angle and raked trees to correct the trail to a manageable number.
If you search the net there are sites with calculators which will help him determine what his trail now is. A few measurements and he will know what to expect. Perhaps this might be a good way to go. There are also entire books written on the subject of how a motorcycle functions. Aprilla has a good one.
You may not be able to stop your friend from high stakes gambling. However when you ride with him, keep your own bike positioned so that if he looses control of his, you will not be affected. It would suck for you to run over him.
Joe
Good points, all.
I've told my sons not to ride with him but if they do, be in front. He values appearnance above everything else. He rode for two years with a nail in his front tire and he knew it. He just kept putting in air every week. Two weeks ago, he had a low speed flat on the front. My sons were riding with him and plugged the tire with those small plugs, and told him to get a new tire. He rode 500 miles to the event with that plug but I finally persuaded him to buy a new tire or have the tire dismounted and a big patch put in from the inside.. I believe that he's an accident looking for a place to happen.
fast joe wrote:
>>Here is another issue to consider on a bike with a telescopic fork. When you panic stop a motorcycle using the front brake, as the front fork compresses and the rear fork extends, it greatly reduces the trail of the bike. On a bike reconfigured as your friend has done, he might not have any trail or even negative trail during a quick stop.<<
Go to youtube sometime. There are quite a few videos of sport bike guys going into a huge wobble after coming down from a high speed wheelie. Front end compresses and trail goes down. Makes for interesting viewing but not funny if you were the one in the saddle.
Took your advice, went to Youtube. Down loaded a bunch of wheelie stuff and some amazing accidents. Real eye openers. Saw a lot of mistakes made that I will try to remember not to make myself. Some of the wrecks you could see it coming from the camera angle but you could see how the rider missed it. One picture worth 1 million words. Definitely a learning tool.
I'll say one thing for the wheelie boys. Some of their riding abilities are right off the chart. Pitty they don't wear leathers. Hate to see all that talent wasted for no reason. Their choice though.
Unlike a lot of folks I run across who are driving with their phone glued to their ear, those riders seem to be watching carefully what they were doing. One fellow seemed almost bored as he rode a wheelie in morning traffic for 3 or 4 miles but most looked pretty alert.
Ran across one flick where a guy went into an amazing tank slapper and was still rolling down the shoulder 30 sec after the bike threw him. Never realized how fortunate I was to have owned mostly bikes with excess trail.
LOL That really quick steering can apparently be over rated at times.
Joe
