I just came back from a 1200 mile trip, which I thought I was gonna die. Coming back, at around 90 mph, wobble was so bad that I thought I was gonna be thrown off the bike. Fellow rides behind me after the ride told me they were for sure that I was gonna be thrown off. I was lucky enough to slow the speed and stablize the bike. After that experience, I did not go over 80 mph and the bike did fine. I have a 2010 RoadKing police model with 21 up front and 17 in the rear with 200 wide tires. The bike has after this ride has only 2200 miles. I also have 16 carlini's gangster apes and the front was dropped 2 inches. I don't want to die and I also want to enjoy this bike, what can I do to relieve this problem. The funny thing is that I sold my 06 street glide because I was afraid of this problem (SG never gave me any problem, but so many people are talking about pre 09 frames and wobbles) Help...

 

Who did the work on the bike to drop the front 2 inches? Was it raked or just lowered? i ask this because if it is not done properly, you end up with a weight transfer to the front of the bike.
when your bike was designed, It was thought out with tech's & computers to get the dynamics proper. That means that things like fork springs, seals, resistance etc have to fit into the design.
If the bike was altered, the front suspension should have been upgraded to compensate for the extra weight.
Do a google search on phrases like "Tank slapper", "Speed wobble" etc. you will see where I am coming from.
Next time your ripping down the road at 90 mph, take a coconut with you & drop it. It will indicate how your body will come apart as you collide with the pavement!
Slow down dude, It's the ride, not the destination!
Hatch.

 

Did you drop the rear too, or just the front? Lots of geometry problems with that. You might be able to fix part of it with a Bagger Brace type hardware. There are a few on the market. I just tightened up my steering head bearing and that fixed my death wobble problems. You might have the dealer check that.

 

The front was "lowered" using progressive suspension lower springs. Maybe I should lower the rear as well to distribute the weight ?

 

Sounds to me like you have a bad mix of things. Your 21" front tyre cannot take anything like as much load as the stock tyre and the geometry may be all over the place with your suspension changes. But first things first, check the bike over thoroughly, for head bearings, wheel and vehicle alignment, tyre pressures, rear shock pressures, etc. There are lots of things that can add up to give you handling problems. Don't change anything else just yet!

 

a friend on mine had the same issue on his 09 streetglide and he also had a 200 mm rear tire. the rear tire was the culprit as soon as he changed it back to a 180 mm rear tire his problem was gone.

 

Mine did it when I put a different tire on the back.
Metzler on front and back I didn't have the problem.
I guess you shouldn't mix tires.

 

I had the same about a month or so ago. New tires but the pressure was way off. I wobbled so hard at 80 MPH that I knew I was going to go down. I've read so many postings about people doing large front wheels and then having issues because of not being balanced properly. I was looking at a 21 and 23. I changed my mind. I'm keeping it stock.

 

Op

On a 21 / 17 combo this is a fairly common occurrence.

What the 21-17 combo does it gets the rake and trail out of spec as the 17 lowers the bike and the 21 raises the bike. By dropping the front by 2 in you've tried to adjust for the increased height of the 21 wheel but you're still out of spec as the rear spec has changed.

Last the 17 tire is probably on a 6 inch wheel and tire pressure is a substantial issue with that setup.

Go back to stock wheels and tires if you still have them and see if problem still exists.

If problem diminishes then you solved most of your issue. If problem continues then it's your front end drop of 2 in.

Best combo high speed stability for the 09 up frame is a 18/16 or 19/18.

Last, check your steering head bearings. Use the new specs for tightness.

 

Thread started in 2010. OP hasn't been around since 2012.