The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Modified Steering Stem
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="davidd" data-source="post: 75838" data-attributes="member: 1177"><p>Rob,</p><p></p><p>In my own case, I tested the shortened springs to a point where I felt the possibility of the Vincent wobble had been eliminated. I found after having guessed at what caused my wobble I could induce the wobble by replicating the conditions: hard braking on a slightly rough road surface. With long springs in place I could release the front brake as the wobble set in and avoid the fall. Doing the same experiment with the short springs simply ended in a fast stop. </p><p></p><p>I would note as a reference to Martyn's fall that although there are reports of wobbles with no braking involved, the common element is lightness in the front end. I found this conclusion in a University paper that Rob posted in the Comet Suspension thread. It seems that when the front end gets light there is potential for a wobble. In Martyn's case the bump he hit caused the front end to get light. It is not intuitive, but lightness of the front end is the cause of the wobble under braking also. It is the seizure of the front end that causes the front tire to bounce on and off the surface which ends up lightening the front end grip enough to cause the horrible castor reaction that we often see in the front wheels of our shopping carts when the frame of the cart is bent just enough so the front wheel barely touches the floor. I would argue that the lack of front end compliance would be the common element in both accidents.</p><p></p><p>Back to the stems, I would hope that testing similar to what I did with the short springs could be done. I was lucky to be able to do back to back testing, but general road testing with some experimentation should yield useful experience. Also, as mentioned above, better front end compliance in general will add to the proof that the mod is working. I think of Norman's experience with Dick Sherwin's D with a disc brake where he found he could squeeze the brake and cause the front end to snap to full extension at will. On a bike with modified brakes and a modified stem you would not be able to do the snap to full extension, the bike would merely slow down.</p><p></p><p>David</p></blockquote><p></p>
[QUOTE="davidd, post: 75838, member: 1177"] Rob, In my own case, I tested the shortened springs to a point where I felt the possibility of the Vincent wobble had been eliminated. I found after having guessed at what caused my wobble I could induce the wobble by replicating the conditions: hard braking on a slightly rough road surface. With long springs in place I could release the front brake as the wobble set in and avoid the fall. Doing the same experiment with the short springs simply ended in a fast stop. I would note as a reference to Martyn's fall that although there are reports of wobbles with no braking involved, the common element is lightness in the front end. I found this conclusion in a University paper that Rob posted in the Comet Suspension thread. It seems that when the front end gets light there is potential for a wobble. In Martyn's case the bump he hit caused the front end to get light. It is not intuitive, but lightness of the front end is the cause of the wobble under braking also. It is the seizure of the front end that causes the front tire to bounce on and off the surface which ends up lightening the front end grip enough to cause the horrible castor reaction that we often see in the front wheels of our shopping carts when the frame of the cart is bent just enough so the front wheel barely touches the floor. I would argue that the lack of front end compliance would be the common element in both accidents. Back to the stems, I would hope that testing similar to what I did with the short springs could be done. I was lucky to be able to do back to back testing, but general road testing with some experimentation should yield useful experience. Also, as mentioned above, better front end compliance in general will add to the proof that the mod is working. I think of Norman's experience with Dick Sherwin's D with a disc brake where he found he could squeeze the brake and cause the front end to snap to full extension at will. On a bike with modified brakes and a modified stem you would not be able to do the snap to full extension, the bike would merely slow down. David [/QUOTE]
Insert quotes…
Verification
The Series 'A' Rapide was known as the '********' Nightmare?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Modified Steering Stem
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top