Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > BMW Forums > BMW Technical Forums > BMW R1100S / R1200S Tech Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
rear tire disappearing - suspension question

I've noticed several times that on sharp turns (hairpin, 1st or 2nd gear, aggressive riding) the rear tire slips a bit and feels like it disappears for a moment on my r12s. This happens under acceleration in the turn not during braking. I'm on the throttle but not too crazy with it. I've noticed this behavior since the bike was new. Stock M1s.

I assume that this means the rear is too unweighted but one would think that under acceleration the rear would be weighted enough not to slip.

What kind of suspension adjustment would help this (keep the rear tire more stable in these conditions)?

Thanks,

Steve


Last edited by swillcox; 06-11-2007 at 06:51 PM..
Old 06-11-2007, 06:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Moderator
 
Jeff Williams's Avatar
 
Join Date: Dec 2002
Location: Central Coast, California.
Posts: 4,397
Steve, before you go 'tweeking' your suspension, just a few questions;
What is your front and rear tire pressure cold,(check in the morning while the bike is in the garage).
Sound to me like your pressure is to high. Remember that these bike have a near flat torque curve and the bike will deliver power to the ground faster than in line 4's.
Try reducing your pressure to 32 front and 34 rear.

what type of stock suspension do you have, and what type of adjustments can you do. Most stock bmw suspensions have only limited adjustments,(including the Ohlins that come with the bike).
jeff
__________________
Riding, releases my mind from the tyranny of petty things. Thats why i ride.
2003 Boxer cup Rep
2113 Multistrada S Touring
95 R100RT Classic, a keeper
Old 06-11-2007, 08:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Moderator
 
roger albert's Avatar
 
Join Date: Aug 1999
Location: Austin, TX. USA
Posts: 11,605
Ditto the above.
Also, a classic sign of too much rebound.
__________________
99 R11S w/ BBP, InDuct, Íhlins, PVMs, Braking, SJ-Filter, ZTech, HIDs
D675 R90Cafe R60/2 M900 SV650-SS CBR150R XR125 & CRF175 Motards


OnRoad OffRoad Cycles, Austin, TX: BMW, Ital, Suspension, Electrics
Dealer for K-Tech, JRI, GP Suspension, Penske, Íhlins, RaceTech, Elka, Wilbers, IKON & Works
www.ororcycle.com

CMRA EXPERT #841
Various Formula 5, 6 & 7 championships 2006-2012

A3, Navigator,
Old 06-11-2007, 09:19 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Underwater basketweaver
 
SergioK's Avatar
 
Join Date: Dec 2004
Location: Seal Beach, CA
Posts: 6,188
Send a message via AIM to SergioK Send a message via Yahoo to SergioK
I know you said you don't go 'crazy' with the throttle, but if the suspension is fine (optimal) in other types of turns then perhaps you are at the limits of the tire's adhesion for those specific types of turns. A hairpin turn will require more grip for turning than other turns (ie, sweepers) and of course accelerating out of a hairpin asks the tire to both turn and accelerate. You only have so much traction at any one point in time. Is it that these hairpins demand much more grip or is the throttle just overdrafting the your traction account? Then again, a slight adjustment in tire pressures may alleviate the entire issue.
__________________
'04 BCR
'05 R12GS
'08 HP2 Sport
Old 06-11-2007, 09:39 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Moderator
 
Jeff Williams's Avatar
 
Join Date: Dec 2002
Location: Central Coast, California.
Posts: 4,397
Sergio,
maybe their is a miscommunication,like me, between the brain and the wrist. I know I feel like I'm going faster than my wrist is telling me.
BTW,
you bringing your new flame to the shindig, are you afraid???????
don't worry, we still love you and will respect you in the morning,(unlike arbik).
cya soon my friend
jeff
__________________
Riding, releases my mind from the tyranny of petty things. Thats why i ride.
2003 Boxer cup Rep
2113 Multistrada S Touring
95 R100RT Classic, a keeper
Old 06-11-2007, 09:57 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Jun 2001
Location: Tallahassee, Florida, USA
Posts: 3,604
Switch to M3's and let the M1's be a memory.
Old 06-12-2007, 01:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
Quote:
Originally posted by Jeff Williams
Steve, before you go 'tweeking' your suspension, just a few questions;
What is your front and rear tire pressure cold,(check in the morning while the bike is in the garage).
Sound to me like your pressure is to high. Remember that these bike have a near flat torque curve and the bike will deliver power to the ground faster than in line 4's.
Try reducing your pressure to 32 front and 34 rear.

what type of stock suspension do you have, and what type of adjustments can you do. Most stock bmw suspensions have only limited adjustments,(including the Ohlins that come with the bike).
jeff
I have 32psi front and 36psi rear. I'll take the rear down for 34psi.
Old 06-12-2007, 07:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
Quote:
Originally posted by Jeff Williams
...

what type of stock suspension do you have, and what type of adjustments can you do. Most stock bmw suspensions have only limited adjustments,(including the Ohlins that come with the bike).
jeff
I have the Ohlins. I never adjusted them to my weight. I weight about 155 pounds plus the leathers and I believe the factory suspension setting is for 180.? I'm planning to adjust the suspension on Saturday when I have someone to help with it. So, I was trying to do some homework before hand...

Last edited by swillcox; 06-12-2007 at 07:56 AM..
Old 06-12-2007, 07:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
Quote:
Originally posted by Dr. Curve
Switch to M3's and let the M1's be a memory.
That will be my next tire.
Old 06-12-2007, 07:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Moderator
 
Jeff Williams's Avatar
 
Join Date: Dec 2002
Location: Central Coast, California.
Posts: 4,397
When I ran M-1's coming out of the corner I would leave a 3-4foot black mark,(heavy handed). Dr.C is right about upgrading to a more modern tire. IMO you should also look at the Pilot Power CT-2,(dual compound tire) and the new pirelli Super corsa. The pilot power is a great rain,dirty road all round tire that has some stickyness to it,(like the M-3).
But I've been running the new pirelli and this tire is the best, bar none, tire I've ever run. I've got 2000 miles on the rear and it looks to be able to handle another 500 miles at least. My former tires,(Super corsa Dragons), would last only 1800 miles. For me sticky is better.
jeff
__________________
Riding, releases my mind from the tyranny of petty things. Thats why i ride.
2003 Boxer cup Rep
2113 Multistrada S Touring
95 R100RT Classic, a keeper
Old 06-12-2007, 12:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Join Date: May 2001
Location: Weston, Florida, USA
Posts: 737
Quote:
Originally posted by swillcox
That will be my next tire.
I'd also consider the Pilot Power 2CT.
__________________
Mal Glanz
Ft. Lauderdale, FL
'12 ZX-14R
'09 CBR1000RR (w/pegs & bars, now my touring bike)
'10 S1000RR & '07 R1200S (gone, but loved 'em)
Old 06-13-2007, 07:49 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
ExarKunONe's Avatar
 
Join Date: Aug 2004
Location: Nipomo, CA
Posts: 930
Send a message via AIM to ExarKunONe Send a message via Skype™ to ExarKunONe
Be smoother with your throttle application! Maybe hang off more to get the bike off the side of the tire, drop your head on the exit.
Old 06-13-2007, 10:01 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
Quote:
Originally posted by ExarKunONe
Be smoother with your throttle application! Maybe hang off more to get the bike off the side of the tire, drop your head on the exit.
I don't think I'm giving it too much throttle for what this bike should be able handle. However, I could always improve on all the other things you mention. From what everyone has contributed here in this thread, I think it's a combo of the tire pressure, the M1 tire, and the suspension needing to be tuned to my weight and riding style, and yes - it's probably my skills as well (I'll be at Miller Motorsports Park with the California SuperBike school at the end of this month so I hope to learn some good stuff there).

- Steve
Old 06-13-2007, 11:53 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Moderator
 
roger albert's Avatar
 
Join Date: Aug 1999
Location: Austin, TX. USA
Posts: 11,605
> I don't think I'm giving it too much throttle for what this bike should be able handle.

Just keep an open mind on that. Under the right conditions, I can spin up my 7hp mini racer's rear end and make it step out.

In fact, if it behaved as you described, then it was by definition too much throttle. All the suspension and tire tweaks will just push the threshhold up a bit.
__________________
99 R11S w/ BBP, InDuct, Íhlins, PVMs, Braking, SJ-Filter, ZTech, HIDs
D675 R90Cafe R60/2 M900 SV650-SS CBR150R XR125 & CRF175 Motards


OnRoad OffRoad Cycles, Austin, TX: BMW, Ital, Suspension, Electrics
Dealer for K-Tech, JRI, GP Suspension, Penske, Íhlins, RaceTech, Elka, Wilbers, IKON & Works
www.ororcycle.com

CMRA EXPERT #841
Various Formula 5, 6 & 7 championships 2006-2012

A3, Navigator,
Old 06-13-2007, 11:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
ExarKunONe's Avatar
 
Join Date: Aug 2004
Location: Nipomo, CA
Posts: 930
Send a message via AIM to ExarKunONe Send a message via Skype™ to ExarKunONe
Also I didnt say use less, I said be more smooth when you pick up the throttle. I've never ridden a R12s but it has a lot o horses and I'm sure will require a gentle touch.
Old 06-13-2007, 12:00 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Oct 2006
Location: Boulder, Colorado
Posts: 84
Quote:
Originally posted by ExarKunONe
Also I didnt say use less, I said be more smooth when you pick up the throttle. I've never ridden a R12s but it has a lot o horses and I'm sure will require a gentle touch.
Got it. Thanks.

Old 06-13-2007, 12:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 08:18 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.