If you want to keep riding these, then you need to learn how fast the cracks are propagating. To do this, mark a few spokes with a marker and measure the associated cracks with a ruler. Wait a few days and measure the cracks again. If the cracks are growing quickly, then you should be shopping for new rims. If the cracks don't grow, then measure them once a week and see where things grow. I have seen spokes pull through with almost no warning, and I have ridden a few 100 miles on rims after I noticed the cracks start.ridewt said:I noticed some very hair line cracks near the spoke holes of my 2001 rolf sestriere rear rim. The wheel still stays in true pretty well and is pretty solid. I suppose this is just a sign of age, low spoke count and high tension necessitated all the more by low spoke count. Trek told me that they don't have any more sestriere rims but I think the bontrager race lite rim is basically the same thing so I could probably rebuild it with that.
My question is how quickly do you think that I should replace the rim? I bet I could ride on this wheel for a long time still but I'm sure that if I mess around with trying to true it, especially in the areas where the cracks already exist, that will just hasten the demise of the rim.
I found a Bontrager rim that should work. I'm curious as to the "don't reuse spokes comment." I can understand that new spokes would be a good idea but the spokes on that wheel haven't seen a whole lot of miles. Is the issue that the are fatigued and will break sooner than new spokes?tube_ee said:Even if the cracks are just in the anodizing, they'll propagate down into the base metal and the rim will fail. This is also why silver rims are more durable than anodized ones. The anodizing is very brittle, so it cracks under the bending loads the rim is subjected to, and because the anodizing is so intimately bonded to the base metal, the cracks spread into the underlying aluminum.
Aluminum is not a "tough" metal. Once damaged, it's ability to resist propagation of that damage is very, very low. Those cracks will spread, and your rim will fail.
It's time for new hoops. Oh, and don't reuse spokes.
--Shannon
What is ERD - something rim diameter? I think the Bontrager rim is a copy of the rolf rim but with Bontrager stickers. From what I remember, Rolf lost his rights to that wheel design and Trek assigned it to Bontrager. I think it's basically the same rim.MR_GRUMPY said:If the erd's are the same, you can reuse spokes. Just don't remove the spokes from the hub. Keep them in the exact same position or you will have trouble with them.
ERD - Effective Rim Diameter. It is the measurement of the diameter where the ends of the spokes will be. In other words, two rims with the same ERDs will use the exact same spoke lengths (assuming the same hub and lacing pattern).ridewt said:What is ERD - something rim diameter?
Well, Rolf Dietrich didn't lose the rights to that wheel design (the same basic design is currently be used by his new company, Rolf Prima). But Trek decided not to renew their license with Deitrich to use the "Rolf" name on their wheels. Trek still licenses the design from Rolf Detriech (although they really shouldn't have to, since the patent should be invalidated by prior art).I think the Bontrager rim is a copy of the rolf rim but with Bontrager stickers. From what I remember, Rolf lost his rights to that wheel design and Trek assigned it to Bontrager. I think it's basically the same rim.
Unless you stuff something into the wheel, spokes fail from fatigue. Each time a spoke passes through the load zone (at the bottom... the rim stands on its spokes), the spoke gets a little bit shorter, carrying the load by a reduction in tension. Wires (spokes) are very strong in tension and very weak in compression. You can bend a spoke in half by pushing in on the ends, but you can't pull one apart by pulling on the ends.ridewt said:I found a Bontrager rim that should work. I'm curious as to the "don't reuse spokes comment." I can understand that new spokes would be a good idea but the spokes on that wheel haven't seen a whole lot of miles. Is the issue that the are fatigued and will break sooner than new spokes?
Just curious, but can you explain to me why people insist on using this bizarre frame of reference? If the spokes go slack at the bottom of the wheel, is the rim still standing on the spokes? Of course not. The hub (and the weight of the rider) is being supported because the spokes at the bottom are reduced in tension and the spokes at the top are increased in tension. This does not mean FOR ONE SECOND that the rim is "standing" on the spokes. This reminds me of people who want to say that spokes are under compression because their tension is less than it was before. Theoretically true, but engineering sophistry at its apex.tube_ee said:Each time a spoke passes through the load zone (at the bottom... the rim stands on its spokes), the spoke gets a little bit shorter, carrying the load by a reduction in tension.
It's a Jobst Brandt reference... Prior to his studies back in the early 1980's, prevailing wisdom was that the hub "hung" from the top of the wheel, and loads were experienced there. In other words, that the load zone was 180 degrees from the point of contact. The chapter in "The Bicycle Wheel" that describes how tensioned spoked wheels deal with loads is called "The Wheel Stands On Its Spokes." That's where the phrase comes from, so far as I know.Kerry Irons said:Just curious, but can you explain to me why people insist on using this bizarre frame of reference? If the spokes go slack at the bottom of the wheel, is the rim still standing on the spokes? Of course not. The hub (and the weight of the rider) is being supported because the spokes at the bottom are reduced in tension and the spokes at the top are increased in tension. This does not mean FOR ONE SECOND that the rim is "standing" on the spokes. This reminds me of people who want to say that spokes are under compression because their tension is less than it was before. Theoretically true, but engineering sophistry at its apex.
Not quite. The spokes at the bottom do reduce their tension, but there is no meaningful change in tension in the spokes on the top. Because the rim is radially very flexible (compared to the spokes), the rim easily flexes inward at the bottom of the wheel, allowing the bottom spokes to be de-tensioned, but transferring virtually none of the load to the top of the wheel.Kerry Irons said:Just curious, but can you explain to me why people insist on using this bizarre frame of reference? If the spokes go slack at the bottom of the wheel, is the rim still standing on the spokes? Of course not. The hub (and the weight of the rider) is being supported because the spokes at the bottom are reduced in tension and the spokes at the top are increased in tension.
Ditto- no such thing as an "ok" crack. It's done!BlueMasi1 said:The question is how much of a gambling man are you? Me, as soon as I discovered cracks on one of my rims I'd stop riding on it.
