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Old 09-30-2013, 09:09 PM   #1
TINK OP
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Front Wheel Hop, R100

My PROJECT-S bike is running great, but, the front tire wants to hop on the crappy, expansion jointed, Los Angeles freeways. Smooth roads don't seem to have as much effect, but she will still hop given the right circumstance.

Any Airhead ridding LA Freeway Slaves out there have a solution? Tire pressure? Tire true (shaving)? wheel balance?

I'm running a new set of Michelin Activ, 30psi, tire/wheel appear to be true.

TINK
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Old 09-30-2013, 09:20 PM   #2
ME 109
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What is hopping?
Do you mean bouncing up and down, or weaving left to right?
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Old 09-30-2013, 09:35 PM   #3
TINK OP
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Quote:
Originally Posted by ME 109 View Post
What is hopping?
Do you mean bouncing up and down, or weaving left to right?
A: bouncing up and down.

When I look down along the fork tube line the forks are flexing fore and aft, like an old over length chopper front end.

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Old 09-30-2013, 10:08 PM   #4
robtg
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Probably a good idea to use fork oil.
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Old 10-01-2013, 12:14 AM   #5
jjwithers
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My bike feels very unstable in the rain grooves. Especially when tire pressure goes low.
I was getting the hop on the last bike I built when the suspension was much too stiff. You need a suspension set up that is forgiving for these terrible roads. Not a race set up.
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Old 10-01-2013, 12:37 AM   #6
Plaka
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Quote:
Originally Posted by TINK View Post
A: bouncing up and down.

When I look down along the fork tube line the forks are flexing fore and aft, like an old over length chopper front end.

TINK
it is a skinny small tube front end. it's gonna do that. but it's at it's weakest when fully extended. how much do you weigh?

The Active front has a groove right down the center. This will make it less stable on grooved pavement. The more center groves a tire has, the worse it will be.

try putting about 40 lbs in your tank bag, strap it on real well, and see what happens.
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Old 10-01-2013, 01:28 AM   #7
pommie john
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Quote:
Originally Posted by TINK View Post
A: bouncing up and down.

When I look down along the fork tube line the forks are flexing fore and aft, like an old over length chopper front end.

TINK
Check your steering head bearings.
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Old 10-01-2013, 01:58 AM   #8
ME 109
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Plaka's on the money. The front end will flex that way. It's a good thing we can't see half of what goes on down there.

Try mounting a bar tread of a ww2 jeep on the front. It will then handle the L.A. rain grooves.
A squiggly centre groove will be the best weapon against rain grooves. Other than that, move to Australia.
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Old 10-01-2013, 03:47 AM   #9
TINK OP
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Springs?

Quote:
Originally Posted by jjwithers View Post
My bike feels very unstable in the rain grooves. Especially when tire pressure goes low.
I was getting the hop on the last bike I built when the suspension was much too stiff. You need a suspension set up that is forgiving for these terrible roads. Not a race set up.
Okay, let's assume... so what front spring would you (Anyone? Anyone?) recommend?
I have the IKON 500-084 spring in there now (with IKON 7610-1298 rear shocks).
Springs are cheap and easy to swap out...
worth a try.

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Old 10-01-2013, 04:02 AM   #10
TINK OP
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BMW Springs?

Some recommend the BMW Heavy Duty spring, part number 31 42 1 232 017, I think.

MAX BMW fiche says for part number 31 42 1 231 358 "Standard. We do not recommend these unless you and the bike are very light weight and you prefer a soft ride and lower seat height."

Are the Standard springs really too soft? Would too soft help me with my LA Freeway problem at a cost to canyon carving ability?

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Old 10-01-2013, 04:54 AM   #11
ME 109
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I have standard springs in my RS
They are not pre loaded.
I run 10 wt. oil. (I think there's oil in there)
My RS handles very well, everywhere.

Standard springs are good for anything you can throw at your bike.
Blowing sports bikes away in the mountains
Blowing GS's away on the trails

Maybe damping is more the issue here?

I gotta see a pic of these LA freeways, they sound awful.
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Old 10-01-2013, 05:09 AM   #12
Plaka
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Quote:
Originally Posted by ME 109 View Post
I have standard springs in my RS
They are not pre loaded.
I run 10 wt. oil. (I think there's oil in there)
My RS handles very well, everywhere.

Standard springs are good for anything you can throw at your bike.
Blowing sports bikes away in the mountains
Blowing GS's away on the trails

Maybe damping is more the issue here?

I gotta see a pic of these LA freeways, they sound awful.
White concrete, much of it grooved---or used to be. Pounded to death with heavy truck traffic. Not many checkpoints in the city proper so trucks run overweight. Big cracks between lanes, sometimes patched with tar. And ample Botts Dots. Traffic is bad and lane splitting legal and accepted, so you spend a lot of time riding some of the worst between the lanes.

Suspension setup depends on weight, speed and riding style, and surface. For a really bad surface, you look to dirt bike type suspensions to cope. The RS has more weight up front and this increases at speed when the aeros kick in. (Never mind the loads certain people favor)
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Old 10-01-2013, 05:23 AM   #13
hardwaregrrl
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I had a similar thing happen a few years ago. Turned out my rear tire was out if round and caused the hop. Check it with a straight edge.
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Old 10-01-2013, 05:58 AM   #14
ME 109
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Quote:
Originally Posted by Plaka View Post

Suspension setup depends on weight, speed and riding style, and surface.
Absolutely.

What is suspension set up?
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Old 10-01-2013, 06:06 AM   #15
spo123
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Try 3 or 4 more pounds of air pressure in front and same in the rear...Please report back IF any difference is felt.
Have a nice day.
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