|Foco life span...||koala|
Sep 20, 2002 7:28 AM
|I spoke with Tom Kellog recently and we talked about ti frames vs. foco. He said foco frames dont last a long time. I have one with a few thousand miles on it and wonder if anyone out there has over 10000 miles on one thats still good.|
|My builder refused to use foco main tubes for the same reasons.||SnowBlind|
Sep 20, 2002 7:46 AM
|He said that foco was lasting only two seasons max for a pro 1/2 rider and Ultra-foco was not lasting an entire season for some.
He claimed it did not braze very well either, but I suppose that is an very subjective opinon.
He does use them sometimes for chain/seat stays as the forces back there are not as extreme.
|What is missing from Kellogs comments are...||sprockets2|
Sep 20, 2002 8:49 AM
|specifics on the failures. If builders use tubes that are too light for the intended application-which they might do trying to make an ultralight steel bike to be comparable to a good Al bike-it is possible that there could be failures. OTOH, such a claim as his should be supported by specific details.
There is nothing inherently wrong with the Foco family of frame tubes that would relegate them to the scrap heap of disposable bikes. Also, there is danger in overgeneralizing from limited info: the fact that I have seen a Kellog produced bike with a broken frame (I have) would not cause me to report that his frames are prone to breakage (I have no evidence that they are).
Sep 20, 2002 4:44 PM
|A standard calculation for tubing tells us that in order to be reasonably dent resistant, a steel tube's walls must be at least 1/50th of the tube diameter. Not surprisingly, for decades the top bicycle tube walls were 0.6mm thick, just about the required thickness. Now, somehow, tubing like FOCO can have 0.4mm walls and still be OK "because they are really light." In fact, these frames will be highly susceptible to denting. Simple fact. Light weight, and easily dented, just what the customer wants.|
|Dent city||Rusty Coggs|
Sep 20, 2002 5:52 PM
|Columbus EL-OS was .4mm in the thin sections years ago.Nothing new here.The OEM16.5 is advertized as .36mm in some applications|
|I agree, nothing new||Kerry|
Sep 21, 2002 4:18 PM
|And I wasn't trying to pick on FOCO. This is the case for all "superlight" steels. Despite the claims of steel fans, this is the key advantage that Ti has over steel at the very light end. Ti's lower density allows thicker walls to get the same weight, but it's strength is still high enough to reduce the tendency to dent.|
|perhaps the problem with foco||rufus|
Sep 21, 2002 5:28 PM
|or the other superlight steels, is the length of the butts. el-os, with the same wall thicknesses as foco, had butts of around 13-14cm. foco has butts of maybe 4-5cm. the longer butted sections allowed frame stresses to be distributed further along the tube instead of concentrated at the point of impact or stress.
i'm guessing that the shorter butts don't allow for stresses to be dissipated along the tube as well, so more stress is concentrated at the joints of the tube, eventually leading to failure.
no one ever accused el-os of being fragile or prone to denting. in fact, it is thought of as being a pretty robust tubeset.
|perhaps the problem with foco||Nessism|
Sep 21, 2002 6:54 PM
|The dent resistance of a tube is dependant on several factors including metal hardness and yield strength. The Thermacrom alloy used in Foco is a fair bit stronger than the Nivacrom alloy used Genius/EL/ELOS ect. and thus is more dent resistant. This is not to say that thin wall steel tubes are super durable, they are not. They are likely to be more durable than many of the super light Al frames these days though.
You pays your money, and youse take your chances.