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2011 road glide, 21” fat mammoth front wheel . Shinko tires. When in a lean of a hard turn, the front feels loose like the bike starts to sway in a lean. Only thing I did differently was put a progressive front suspension with 1” lowing. Can anyone give me some hints are why the bike feels unstable. It does it as well if I’m above 75mph and I’m catching air off the vehicle in front of me
Congratulations on your first post to HDF,
to the Forum.
You changed the rake & trail of the bike, you need to look at the setup and see which factor is causing the issue. If you did not do the correct calculations you will have issues.
Your front suspension geometry is defined by the following six variables which are:
OFFSET: Centerline of the top steering neck to the centerline of the top of the fork tubes. RAKE: The angle in degrees of the steering neck from vertical. FORK LENGTH: The distance between the top of the fork tubes to the centerline of the axle. DIAMETER: The diameter of the front tire. TRAIL: The distance defined by the vertical line from axle to ground and the intersection of centerline of the steering neck and ground. RAKED TRIPLE TREES: In order to bring trail figures back into line, triple trees with raked steering stems can be used. Usually adjustable in 3, 5, 7 degrees of rake.
TOO LITTLE OR NEGATIVE TRAIL
With too little or negative trail (steering axle mark behind the front axle mark), the bike will handle with unbelievable ease at low speeds, but will be completely out of balance at high speed. It will easily develop a fatal high-speed wobble. EXTREMELY DANGEROUS!
NORMAL TRAIL
Normal trail is somewhere between 3 and 6 inches. The bike will handle easily at both high and low speeds. Flowing smoothly through curves without swaying or wobbling. If you use a very fat rear tire, you should keep the trail as close to 4 inches as possible.
TOO MUCH TRAIL
If the trail is more than 6 inches the bike will handle sluggishly at high speeds. It will seem almost too steady. You will have trouble balancing the bike at lower speeds or on winding roads. It will feel generally sluggish and clumsy.
NOTE:
The above information, while credible, is worth what you paid for it and should not be considered gospel.
Do due diligence, research and have a H-D Field Service Manual before working on your bike.
You will probably have many opinions and suggestions presented; make sure you research the person providing the helpful information as there are some who provide good information that is useful and some who speak out of other orifices with gibberish. You will figure out this quickly.
Last edited by CoolBreeze3646; Mar 31, 2024 at 11:11 AM.
What tire pressures are you running? I have read on various forums that Shinko recommends that you should run their tires at max cold pressure stated on the tire, now I take everything with a grain of salt unless, I hear it from the man himself, however; I am running Shinko 250's, and find that they do run/handle better at higher pressures, I did not run them at max pressure, though I have migrated up the scale and right now I am running 38 PSI (2 PSI higher than what Harley recommends for my bike), so maybe play with your PSI's see if that helps, cost nothing.
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