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725 reynolds chromoly(5 posts)

725 reynolds chromolyrollinrob
Dec 12, 2002 5:43 PM
Any Good? I am considering buying a bike that has top tube and seat made of this stuff. Down tube and seat stays are made with reynolds 853. Seems like a strange mix. Any comments?
RR
re: 725 reynolds chromolyRusty Coggs
Dec 12, 2002 9:37 PM
Yes, abit strange but the 725 is strong heattreated stuff and the stronger 853 is in the right places.
re: 725 reynolds chromolytarwheel
Dec 13, 2002 4:54 AM
Reynolds 725 is high quality steel and very close to 853 in strength. Here's what the strongcycles.com web site says about both metals:

Reynolds 853, Air Hardening Heat Treated, Ultimate Strength 180-210 ksi, Reynolds flagship tubeset. The strength to weight ration is equal to that of quality titanium tubes. These tubes are heat treated and air hardened when cooling, adding strength well in excess of as delivered values in the critical joint areas. 853 also increases stiffness through reduced micro-yielding at the joints.

Reynolds 725, Heat Treated, Ult. Strength 157-186 ksi, 725 is a hybrid heat-treated Chromoly alloy. Precision butted on mandrels, 725 is offered in a wide range of tube sizes. 725 is a material that allows a thin gauge tight tolerance tube providing healthy weight savings.

I was considering buying a custom frame where the builder uses 725 on a lot of his frames. He considered it nearly as good as 853 and comparable to Dedaciai Zero Uno, which is another very nice steel. Bottom line, I would worry about the 725 tubes in the frame; the builder probably used them for a good reason.
Reynolds recommends 531 forks with 853 frames.dzrider
Dec 13, 2002 8:56 AM
Their website doesn't mention 853 forks and stays and I've been under the impression that they don't make them. 725 is good light stuff and some real good frame builders use it. I don't think it's unusual to use 725 forks and stays with 853 frames.
Reason why...Nessism
Dec 13, 2002 10:25 AM
A tube only needs to be "strong enough" to resist the stresses and not brake. In the case of a steel fork blade, the basic shape is dictated by convention for the most part and 531 (or regular chromoly steel like 525) is strong enough for the application. Another consideration regarding 853 is the fact that the material should not be cold worked by the builder (according to Reynolds). Bending the fork blades, which is done to make the rake, would fall into the cold working catagory. Lastly, many of the high strength steel materials, like 725 and 853, have a lower elongation limit and thus are more brittle than 531/525. It is far safer to have the fork bend/deform rather than have it snap off with a brittle failure should an unexpected event occur, such as striking an object.

Bottom line - there is some method to the madness.

Ed