I designed and built a bike (frame and front-end inclusive) and used the earles front forks design as a starting point. The front end has an enharent wobble in it and I am looking for someone with some expertise in this area that can possible help. Thank you in advance. Dennis.
Dennis,
Assuming you have taken rake and trail in consideration as you were designing your frame, the factory equipped cycles with Earles type leading link suspension still use a steering dampener. Usually the old style friction type. If you cannot adapt this type of damper, the piston (shock) type is easily adapted. Mount it so that it doesn't interfere with the ability to make full lock turns in either direction though.
If the wobble appears when starting out and when driving very slow or stopping, this will take care of it.
If you get the front end wobble at all speeds, you need to go back to the drawing board with your front end geometry. Hal Kendall's "Riding With A Sidecar" book covers this area quite well.
Lonnie Cook
Northwest Sidecar
nwsidecar@aol.com
Lonnie, that is exactly what is happening, Well maybe not exactly because I was too concerned to make it go faster after the wobble. Let me give more detail. I built this bike over the last five years (will post pics soon) and last year, the last time I rode it, (just in the sub, the bike has never been over 45 or 50) the front end went crazy, hitting my chest with the left side of the ape hanger bars, then a split second later, hitting my chest with the right side. It was all I could do to hange on and really thought about jumping off the bike. It was the most violent wobble I have ever experiences....all at around 30mph. I took the bike back to the garage and found that the stem nut had come loose. I put the bike away that day and let it sit until yesterday. The first thing I did was to tighten and preload the Triple trees, and lock down the stem nut. When I rode it yesterday, it seemed like it wanted to wobble at slow speed, and when I pushed one side of the bars, it did wobble a tiny bit but not bad, and then settled down. Something else, when I turn at slow speed, the front end pulls itself into the turn, more than I want it to, so I end up pushing it back more towards normal, and holding in the turn. Is this also part of this type of front end? Thanks for your help.
If the front end seems to "fold up" when you turn, you may have too little trail or even negative trail. The leading link does make steering easier but should not make it manditory.
Check the book I mentioned, then do some measuring and see where you are rake and trail wise. It seems you have some adjusting to do. Moving the axle forward may help.
Lonnie
Thanks Lonnie, I'm trying to find a copy of Hal's book. I am new to this forum and do not know how to post pics of the bike but will as soon as I figure it out.... Cheers.
Thanks Fender, Right after I posted that note, I found the links. My bike is a two wheeler (no sidecar) with a sidecar style front end. In reading Hal's book, it talked about taking the side car off a bike with a leading link front end that is rigged for a side car, standing straight up on the floorboards and watching the bike just come unglued when it hit 35 mph.....that is exactly what happened to mine. So, after reading, it sounds like my options are to dampen the front end or make new leading links that will pull the axle back an inch or two.
then again all you'd really need to do for an easy fix
is simply put a sidecar on the bike,
sorry had to say it
fender
Aw shucks, Dennis,
I thought you already had a hack on the side.
If you're staying solo, go for the increased rake and trail. Solos with the damper installed have been known to go into a tank slapper at high speed. I had a customer with a Road King who took his sidecar off and left the steering damper on and just about bought it at over 95 when he got his tank slapper wobble. When he took the damper off, the wobble went away.
Lonnie
Sorry if I was misleading Lonnie, its just that this is the only forum that knows anything about earles front ends. I can remake the leading links shorter by 1 to 2 inches, that should do it. Hal's book has been very informative, as well as Tony Foil's (SP) book on motorcycle design. Cheers. P.S. I will post pics (even though it only has two wheels) ASAP.
Dennis,
You weren't really misleading, I assumed, broke the old law of "Never Assume".
On bikes, whether you have one wheel (unicycle), or five (hack & trailer), wheel wobble can be hazardous to ones health.
Besides, you started out with none and you're all the way up to two wheels already, who knows where you'll stop at this early date.
Stay in the wind,
Lonnie
I know I am coming into this a little late but....
When the world was younger (and so was I) I had a BWM solo that I had picked up in oh, about 69 or so. it had Earles type leading link suspension up front. Now that unit had two mounting holes in the link of which only one was used. After some reading and asking questions I found out that was so you could set up the front end trail for either solo or for use wih a hack. Back then I thought that was a neat idea, still do. That may be all you will need to do with a redesign. Copy and older Earles type leading link suspension system. Some time later I understand BMW did away with the second set of mounts.
Hope that this helps.
Thanks all for your input. I am up against a wall here. Let me explain. The shop where I built this bike (Finch's custom cycle) is now involved in a Discovery Channel Biker Build-off against Rooke Customs. We have to build a ground up custom and ride it to N. Carolyna by 7/3! We are starting this morning and the film crew will be at the shop tomorrow morning. Here is my problem. I have to ride my bike to NC and this wobble thing is driving me crazy. With the head bolt tightened up, the bike only WANTS to wobble at slow speeds. I have looked at all the dampner possibilities and none will fit my tight quarters. What is your take on this WANT of a slow speed wobble turning into a high speed wobble? I just don't have time now to do the full redesign/rebuild. THanks for all your help. Cheers.
You might snug up the neck bearings so the front end doesn't flop. Put some weight inside your handlebars (at least the outer several inches).
Take a buddy and find a straight deserted road. Have him (or her) dial 91 and keep their finger on the 1, and you take off like a bat out of hell.
Good Luck Pardner,
Lonnie
You might snug up the neck bearings so the front end doesn't flop. Put some weight inside your handlebars (at least the outer several inches).
Take a buddy and find a straight deserted road. Have him (or her) dial 91 and keep their finger on the 1, and you take off like a bat out of hell.
Good Luck Pardner,
Lonnie
