• Can't post after logging to the forum for the first time... Try Again - If you can't post in the forum, sign out of both the membership site and the forum and log in again. Make sure your COG membership is active and your browser allow cookies. If you still can't post, contact the COG IT guy at IT@Concours.org.
  • IF YOU GET 404 ERROR: This may be due to using a link in a post from prior to the web migration. Content was brought over from the old forum as is, but the links may be in error. If the link contains "cog-online.org" it is an old link and will not work.

rear tire "hop"

M

martyinSC

Bicycle
After going through two Pilot GT rears in the last few years I went to BT45s last August and have racked up about 6000 miles on them.  I got about 13k miles on the GTs but changed them out a little prematurely.  The BTs have performed well but I have noticed some sort of slight side to side wobble in the bike at low speeds.  When I had the bike up on the center stand over the weekend and in gear I noticed what I would consider a significant shift in the tire as it rotates.  It appears to be side to side, a little less than a 1/4" of movement (looks like a bicycle wheel that's out of true).  The rim appears to be rock solid with no similar movement, the tire looks to be evenly and completely seated on the rim, the suspension doesn't feel any different, and I can't feel any sideplay on the wheel itself. It was installed at a local shop but I don't think it was balanced.  Did I get a bad tire or are there other issues I should look at?  I think the movement has prematurely worn the tread as it appears there's probably not much more than 1 or 2k miles of tread left but they're coming off real soon as I don't trust it in this condition.  I'm not a real aggresive rider but I don't doddle around either.

Thanks for any help or suggestions.
Marty 
 
Most likely it is the tire.

If you have access to a dial indicator check the tire and wheel "runouts". The vertical outside surface planes of the wheel and tire should be flat and true throughout and spinning it with a dial indicator touching the surface will show if this is the case and whether or not it is within spec. Check both the axial (vertical) and radial (the actual edge of the wheel - easier to do without the tire on, but still do-able). Axial rim runout is no more than 0.5mm and Radial is no more the 0.8mm

This will tell you if the rim is out of round thus causing the issue.

If these are within spec then the tire itself is at issue and should be replaced as most likely there is internal band separation. Not a good thing!

If you do not have a dial indicator try clamping a phillips screwdriver in pace dso that the tip is barely off the edge of the rim, say 0.6mm. Slowly spin the rim and if the rim touched the tip of the screwdriver then you are out of spec at that location.  Check the opposite side at the same location and if there is a dip at the same spot on the opposite side you definitely have a warped and or bent rim. If there are multiple locations perhaps a good deadblow mallet is required to "straighten out" the bent section(s). But if it is really way out there then replacement would be the prudent and safest thing to do. Unless there is a rim straightening service available in your area.

Best of luck
 
If the tire appears to be properly and evenly seated as you said, then it likely IS the tire.  You certainly wouldn;t be the first guy to get a new one that wasn't good.  It happens to every manufacturer despite their efforts in quality control.
 
I just experienced a similar thing on my rear tire, there was a slight indentation visible in the tread going from bead to bead across the tire. I felt a vibration riding around town. When I pulled it off, there was a bubble on the inside of the tire about the diameter of a silver dollar.  :eek:

I'm thinking as Bob said, a seperated belt.
 
Thanks for everyone's input.  I did check the rim and it's fine in both the axial and radial directions.  Going to get a new tire mounted up this week. Sticking with the BT45 for now.
 
You must log in or register to reply here.
Top