Saturday, March 24, 2007

Chromed Tires?

On 10 July 2006, I rode 1200 miles to see my brother in Austin, TX. The next morning, when I did my morning T-CLOCK exam on the bike, I noticed that my rear tire had cracks in the carcass. So as well as catching up with a brother I hadn't seen in over a decade, I spent part of Skylab Day 2006 getting new rear rubber. It was a Metzeler ME880, the only rear tire for my bike that was in stock. It has been a decent rear tire. Good grip in the rain, and it was wearing quite well. Was.

Last Thursday night, I changed my spark plugs and checked the tires. It looked to me like I was going to get another 10K out of the rear, and it had not lost a single pound of pressure (I've only had to add air once since I got the thing, and I think that was only from the little bit that escapes every week when I check.) Little did I know.

While riding in to Lake Lure to pick up a couple more riders (Phil & Barb), I thought my leg was twitching. Then I realized that it was my foot peg that was pulsing against my foot, and not vice versa. Cruising slowly through Chimney Rock, I noticed a wobble. It was not the dreaded decel wobble. It happened most severely ~20 mph, accelerating, decelerating, or holding steady. As we headed up NC 9 toward Black Mountain (and coincidentally crossing the eastern continental divide), I rode more conservatively than I usually do and paid closer attention.

I wondered if maybe the front tire were severely out of balance, and was dreading the talk I was going to have to have with the shop that only a couple thousand miles ago rebuilt my 80K front end. Tapered bearings gone loose? There was no clicking, so I didn't think it was wheel bearings. But those handlebars sure did want to dance. By the time we got to Black Mountain, I was wondering whether and how we would be getting home.

I mentioned this over a lunch of some fine smoked brisket (really; you HAVE to go to Perry's) and there was a good bit of discussion as to possibilities. I didn't want to actually put hands and gauges on the tire until it had cooled down and I had filled my belly, so this was a good delaying tactic. And people suggested the things I had been mulling over. Phil mentioned a possible de-lamination, which I had NOT considered, but which has been a problem with E3 fronts (built by management during the recent Dunlop strike). My front is a Stone.

A couple of us poked & prodded the front end a bit and found nothing obvious. It took Dan walking up from behind and asking, "what's on your back tire?" to spot the trouble. What Dan was seeing were the steel belts on the left side of the tire. I HAD had a de-lamination and had thrown the tread off the rear. Steve mentioned that while following me over 9 at one point he had though that I had picked up some road trash when he saw something fluttering on my rear tire. Ah.

I had had well over 1/8" of tread in the center of that tire a day and a half earlier; a good 1/4" toward the outer edges. Now I had steel belts. How do you measure thread depth? Does steel grip well in the corners? Can you have it chromed as the ultimate Wing accessory?

After a brief discussion of best course of action, we put Lizzy behind Jim (sorry, Dixie) and Phil took point toward MR Cycles in Asheville. I rode second, and the other seven bikes rode behind, making sure no one ran over me should the worst happen. We even took some of the BRP this way to get around Asheville traffic. MR had an E3 in stock, and 90 minutes and $221 later, we were back on the road.

For the record, that tire had 9774 miles on it. (Yes, I know -- only 10K miles in 8 months; I'm not going to make my average this year. I blame it on the new commute; only 20 miles a day instead of 50, and I won't have as much chance to catch up this summer, given the nature of our vacation plans.) I ran it at 42 psi.

And thinking about it now, I'll bet that this explains why the back end has felt so squirrelly in a lean lately. I was just talking about trying to sort this one out last Saturday at McGuire's in Summerville. Every time I've leaned aggressively lately, the back end has slid a bit to one side. I haven't touched a peg down in months.

So... Good news: 1) I've still been sensitive enough to notice when there's trouble and to adapt my riding style as necessary. 2) The steel belts held well enough to get us up NC 9 two-up and then over to MR Cycles solo. 3) No get-off, no harm, no foul. 4) MR was fast, friendly, and reasonable. I can see why Phil & Barb ride up from Brevard to use them (aside from the fun roads betwixt & between). 5) We didn't hold up the group ride too long. 6) Mike Parks bought a new helmet. 7) We met some new riding friends. 8) Excellent brisket. 9) Fun roads. 10) 400 miles with an average 40 mpg for the day, with lowest top up at 38 and highest 42.

Bad news: 1) I would have sworn that the problem was in the front. I should have been able to tell that it was in the rear. My backside used to be more sensitive than that. 2) The frikkin rear tire threw off half its tread! We coulda died!

Next steps: 1) Write a letter and send a picture to Metzeler. 2) If there's a ride next weekend, sit it out and give our guardian angels the time off. They must be exhausted.


Update: Lizzy has also blogged about this, and has included a couple of pictures. She has also put in her linked photo album some of the pictures sent by Jim and Mike.

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