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I just noticed slight decel wobble!

2K views 23 replies 11 participants last post by  Pigeon Roost 
#1 ·
Almost 7,900 miles, some roar in the corners from rear. Mostly through a long ride in back roads and on a very rough section of patched pavement and with hands on I thought I perceived the vibes. So I took my hands off the bars and sure'nuff the White Knight wobbled. I repeated several times and it is chronic. Probably the tire wear, but it is going to rain a lot this week and weekend so I will check the "head" bearing torque. I do have a new set of tires too.

prs
 
#9 ·
Sort of, very vague on close inspection. On the outer quarters of each outer side between sipes is a repetitive pattern of thumb shaped very shallow depressions, nail end of thump pointing in direction of travel. I could not see that until I washed the tire.

Rear tire pictures?:smile2:
Steering stem nut has been known to be loose. 76 foot pounds, 30mm.
Will be checked RE the nut. The tire was muddy so I washed it to see if a pic with my iPhone would capture any odd wear. it did not. Need better light to have any chance. Wear bars are maybe a thou or two below in center and a little more tread left where the odd scalloping is. B'stone original tire, probably just how they will wear.

When I had mine off the other day my steering nut rotated about 180 degrees before the click of the wrench.
Yikes!

prs
 
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#5 ·
Rear tire wear bars have bloomed on outer quadrants, dang these here WV hills. lol. I have a new rear tire mounted on a spare rim and this original will be for my Darkside tire mount. The front tire is very evenly worn without cupping. The trailing edge of the rear tire's sipes are a little bit feathered from acceleration stress, I don't think a pic would show that very well. I will still check the steering bearings' torque on a rainy day, it is not a difficult task using the short-cut method for getting the center control panel out of the way.

prs
 
#6 ·
When I had mine off the other day my steering nut rotated about 180 degrees before the click of the wrench.
 
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#10 ·
You're obviously an experienced and knowledgeable hand PRS, so you probably already do this. I find that scalloping is easier to notice and how bad it actually is by looking at the tire from many different angles and also by feel, from running my hand along the surface in both directions. The trailing edge of each tread block will feel more pronounced and "sharper" than the front. That scalloping is what begins the wobble, as you already know.
 
#13 ·
Your description of scalloping is consistent with my observations on other bikes. This tire has a different pattern of wear, the thumb shaped depressions I noted above are in the plain areas between the major sipes. I do not know yet if that will be typical for this tire model (BS) and bike or if this is an anomaly.

prs
 
#14 ·
I refrain as it is partly in my knowledge due to Fred's video sight and I will not infringe. There may be a YouTube for you.

Check out Fred Harmon's VIMEO sight to see if his excellent short-cut video is one of his freebies. If it is or if it is not, DO subscribe! That is a very rich resource at a bargain price. Sometimes you do get more than what you paid for, this is one of those times!

prs
 
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#15 ·
Now that is an obvious source that I have not YET checked with this wobble. I have checked it in the past, and WILL check again. I do not have a set of the pins, but if they are really sloppy I should be able to tell. I really think the main input is the worn rear tire. I plan on checking the steering top nut first and then ride. Then I will address any issue with the right tie rod and check, and then change the tire. I plan on another post relative the changing the tire by means of a spare rim and new tire from trike take-off. keep an eye out for that please.

prs
 
#20 ·
Is 7900 miles typical on a rear tire, or does that relate to the type of riding you do? I get the impression you do not ride casually, but with intensity. Are Bridgestone tires known as low mileage? Other brands better at giving longer mileage with moderate riders?


Sounds like you are enjoying the ride!
Jim
 
#21 ·
My experience with OE type Bridgestone tires on the previous model GL18 is similar to what I notice on this bike. I used to ride more aggressively, but have moderated my pace. I still cut it up in the mountains some; so mixed bag riding. I am really good about not over inflating or riding on low pressure tires. Front tires typically last about half again as much as rears. Avons similar wear rate, Dunslips on previous bike lasted longer, but the grip was not confidence inspiring. I really have no problem trading long life for better grip.

prs
 
#24 ·
It continues to rain, so after work I followed Fred's demonstration of a short cut to check the steering head top nut to see if it was loose as Hairball noticed with his. I marked the nut and stem before applying torque and set the torque wrench to its setting where it alerts you as you approach the target torque and beeps when you are there. At 68 foot pounds of torque the top nut began to move and by the time I hit the specification(76ft#) it had moved only about 6 degrees of rotation. Now this is only the top nut and I did not tear down to the bearing preload adjustment as my strong clinical hunch is that the tires are the source of the decel wobble in this case. If it had been goose loose, I would have gotten a helper to hold the bottom end of the stem while I checked and re-set the bearing preload. I did order the test pins and Traxxion tie rod today, but that is likely a future project.

prs
 
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