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X’s and O’s
My request is for an explanation of the difference between an O-ring chain and an X-ring chain. Do they require lubrication and/or maintenance? Is there a preference for one over the other?
Humberto C. Martinez
The O-ring and X-ring description refers to the type of seals used in each link. In either type of chain, small seals between the inner and outer plates are used to keep grease in the pins and bushings, and keep dirt out. In an O-ring chain, a standard O-ring is used — essentially a tiny donut-shaped seal. An X-ring seal is a type of O-ring, but has an X-shaped cross section rather than circular. There are a number of advantages to using an X-ring: A standard O-ring, when squeezed between the inner and outer plates, deforms and has a large surface area. But when an X-ring is placed between the inner and outer plates, it twists as opposed to being squashed, and two smaller sealing surfaces are created with less friction and wear. An X-ring also distorts less than a standard O-ring, and the gap between the sealing surfaces does a better job of retaining grease. According to D.I.D, its X-ring chains last twice as long as its O-ring chains, 20,000 miles vs. 10,000 miles. Both require regular cleaning and lubrication; even though the seals keep the inner components of the chain lubricated and safe from dirt, the external rollers and plates need lubrication, as do the rings themselves.
Plugging and Patching Revisited
I just wanted to make a quick comment about the answer you guys provided about plugging/patching tires (Ask the Geek, June ‘12). In 2009 I pulled my bike out of the garage and noticed my rear tire was flat. I inspected the tire and found a nail stuck in it. I looked into fixing the tire and the advice from everyone was, “Replace it, it’s cheap insurance.” I’m not the superstitious type, so I decided to fix the tire, as my research led me to believe this insurance may not be money well spent. My justification for this was the fact that if I was able to run over a nail in the first place, then who’s to say it won’t happen again. The best insurance would be not to ride, as nails, glass, rocks, etc. are all over the road. Besides, Dunlop seemed to have no problems with me doing so.
So I fixed the tire using a plug patch, monitored the repair and tire pressures for the next few rides, and once I was satisfied the air wasn’t leaking I dropped the worries out of my mind. One interesting thing of note, and the reason I’m actually writing you, is the comment people make about the track. Including in the response where you wrote: “For any kind of track use, however, I would still opt for replacement rather than any kind of repair.” I can understand this and it’s probably good advice, but it’s not to say one couldn’t use a patched tire on the track successfully. I mainly use my bike on the track (rare street riding) and the tire finally wore out with 1500-2000 miles on it and seven track days. Given similar type of damage, I’d have no qualms about patching my tire again and bringing the bike to the track—though once again, I’d inspect the tire and monitor pressures for a short period of time. The track I ran these tires on was Monticello where I reached speeds of 160 mph as indicated by the speedo.
via SR Mail
While you managed to get quite a few miles and even some track days out of your tire after repairing it, I’m not convinced it was a wise decision. Dunlop does have a problem with you using your repaired tire as you did, especially at the track. According to the company’s information, even with a plug patch repair, “the repaired tire should never be used over 75 mph.” To me, your savings do not come anywhere close to offsetting the increased risks. The cost of a new tire spread over seven track days is negligible, especially when compared with the other costs associated with a track day. Add in the increased risk of a crash (however minimal you may think that is), and riding on a repaired tire for that long is simply not worth it.