Originally Posted by
Road Fan
Looking at a frame made with thinwall tubing in standard non-oversized diameters. TT 7/4/7, DT 8/5/8, ST 9/6. The OD's would be respectively 25.4, 28.6, 28.6. The builders say the steel will be non-heat-treated. I assume the alloy is at least 4130. My question is, is it acceptable to have such thin tubing walls without a heat-treated, higher strength alloy such as Nivachrome or 853? Seems to me the main risk here is ease of denting the tubes - higher yield strength should absorb more force or impact without yielding.
What do you say?
Why would the ST be thicker-walled than the DT? That sounds backwards, and would give you a less-than-27.2 post size. Usually, a ST is .5/.8 and a DT is .9/.6/.9 (that's what standard 531DB was for decades, for example).
If you have those two reversed, then those aren't particularly thin. Just the TT is 0.1 mm thicker than 'standard.' No big deal at all. Top tubes don't do much, really. Is it Kaisei tubing?