Suttree

I've been kicking around the idea of getting a new frame--I have a very serviceable
single speed but the largest tires it accommodates are too small (28mm) for
the smoother ride I think I want. There is a range of conflicting information
and hyperbole out there--it is hard to sort out. Some people build touring bikes
out of Tange Prestige--others say it is too soft

"A frame built from Tange Prestige tubing will give a great ride to a sub-150-pound rider, but the same frame in the hands of a 200 pounder will be too flexible and may actually fail in use."

Other bikes seem to be made from very strong steel but the physics of it all are beyond me (for instance
the strength rating of OX Platinum or what have you. Anyone have any thoughts, particularly about the Tange Prestige issue? Is there a difference between the strength in brazed vs. welded Prestige frames?

JohnDThompson 

Tange Prestige was heat-treated "Champion" chrome-moly tubing, much like Reynolds 753 was heat-treated 531 manganese-moly tubing. In each case, the heat treatment was applied to increase the strength of the tubing, allowing it to be drawn thinner for a lighter frame. Heat treatment does not affect the flexibility of the tubing; that is a property of the physical dimensions of the tube. A thinner tube will always be more flexible than a thicker tube of the same diameter and material; hence the caution that heavier riders may find these thin-wall tube sets to be more flexible than is desirable.

Regarding welding Prestige tubing: I suspect that the heat of welding would remove the advantages of the heat treatment in the weld area, resulting in a joint that is no stronger than a non-heat treated tube of the same material. Given the thinner wall of the Prestige tubing, this would likely result in an unsuitably weak joint -- that's why they went through the bother of heat treating it, after all.

Nessism

My understanding is that Prestige is heat treated 4130 - the "prestige" was in effect the heat treatment process. The metal would loose some strength in the heat effected zone but not enough to damage anything - that's why the tubes are butted.

Tange made Prestige tube in a wide range of diameters and thicknesses. The old standard road tubing is what many people think about but Prestige mountain bike tubing was also out there in just about any size a builder could want, as long as the builder is willing to fillet braze or TIG.

For a big rider on a loaded tour, I'd look for something pretty thick. Using oversized tubing in the 1.0 /.7 butted range would be reasonable I think. You could even go larger on the tube sizes if you are looking for something killer stout - although the frame would ride pretty rough.

Good luck.

Suttree

Thanks guys--
It looks like Tange Prestige is 8-5-8 butted with different butting profiles
depending on the specific tube set. Interesting advice.

NoReg

One of the rules is that the all up weight is not as big a variable as the dynamic stuff. A heavy rider does not necessarily require a heavier built bike, if he is gentle and/or under powered. An Eric Heinden on a rampage is another mater altogether. For the latter kind of rider a straight wall .035 4130 main triangle in suitable size can be a good choice on a touring bike for a bigun. Not fancy but actually a pretty good material. There was a thread somewhere recently about a powerful track rider in CA who was also a frame builder, with his own track no less. His final solution was straight wall with gussets. The weight increase is only a few ounces a tube, and the money savings is only a few bucks, it gets done cause it works under certain situations.

lighthousecycle 

When I designed the first Specialized Expedition bikes I used 1.0/.7 mm. downtubes with 1.0mm chainstays and forks with a bit lighter tubes in the upper parts of the frames. The bikes were legendary as fine touring bikes. I would apply the same philosophy for a frame for you but up dated to take advantage of the newer oversized steel tubes now available.
Cheers
Tim

Nessism

Again, Prestige came in a wide range of diameters and thicknesses. .8/.5 is the thin stuff, not stout enough for loaded touring unless you are talking about using MTB type diameters.

Thylacine

It's really hard to give much advice because there's too many variables.

If you're after lugs or a 'traditional' look, then you're limited to smaller diameter tubing which means you have to have relatively thick walls.

However, stiffness is a result mainly of tubing diameter, so if you're not limited to 'traditional' diameters, then you can go up in diameter and down slightly in wall to get a stiffer frame.

In terms of tubing brands, Prestige has always been good quality, but it's just a heat treated 4130. I find it hard to go past the 'air hardening' tubing that's TIG welded because the joint strength is double what regular 4130 can deliver.

Nessism's opinion is inline with my own - the tubing I'd use for a mountain bike is pretty much the same as I'd use for a touring frame.

NoReg

"I find it hard to go past the 'air hardening' tubing that's TIG welded because the joint strength is double what regular 4130 can deliver."

I've never seen any numbers on that. Do you know any? It is one thing to have an alloy that air hardens to higher numbers and another to have any evidence that is happening in a reasonable way in a process like TIG welding, not the normal pinacle heat treatment method. And beyond that I don't see any particular evidence the extra strength is needed since 4130 is an aircraft approved product in un-butted tubing. With butted tubing there is additional redundancy. Not saying it is a bad choice, but I wouldn't be lining up to buy it for the weld strength. Seems all part of the poison that exists in this craft that starts on the false premise that welding is inferior, and wastes a lot of time trying to fight out of that bag.

Big Steve

+1 to Peterpan1's comments re joint strength. The air hardening alloys might have 2X the UTS of normalized 4130 tubing of the same dimensions, but that does not translate to 2X the joint strength.

I believe that Tange Prestige was heat treated CroMo of some subspecies similar to 4130. Tange made nice clean round tubes, but there is plenty of stuff available these days that is just as good or better.

Thylacine is correct that larger diameter O.D. is the better way to get adequate rigidity for a big guy and/or touring with gear. The 1.0mm wall tubing was relatively common for track bikes <1980 when lugs sizes (max 1-1/8"/ 28.6mm DT) limited tubing diameter choices, but there's no need to go with such heavy wall tubing with all the large diameter tubes made of super strong steel alloys available these days. We first experimented in the late 1970s with larger (1-1/4", i.e., 31.8mm, x 0.35", i.e., 0.9mm) straight gauge 4130 DT's, and the step up from 1-1/8" (28.6mm) DT's made for substantially more rigid frame.

Peterpan1's recommendation of a fat 4130 downtube is sound advice. In 1981, when I weighed a solid and strong 235 lbs., Doug Curtiss (the "Curt" of Curtlo) and I (the "Lo") rode to Alaska with frames built with 1-3/8 (34.9mm) x .035 (0.9mm) straight gauge 4130 downtubes, and we truly abused those frames for years with no failures.

+1 that most MTB tube sets would work fine.

I'm now north of 235, and I built my last two frames from thin-walled large diameter Columbus Spirit/Life mix with Pacenti over-oversize lugs (34.9mm DT, 31.8mm TT, ST). I have not had panniers on these bikes, but I am confident that they would tour great. However, if I were to get back into rugged long distance touring, I'd likely go with a 0.9mm butted 31.8mm Nivachrome ST, a lighter 31.8mm TT, a 0.9mm butted Nivachrome or 4130 0.9mm (.035") straight gauge DT, and some beefier CS's than I am currently using. YMMV, of course.

NoReg

I have to confess that I collect reasons as to why 4130 is the best choice. And I can fill a long list. But I am also a luddite on the tubing issue. I know the better tubing is great, but there is a certain aspect of it that is marketing driven, some of it that is for the go fast boys only, so I try to convince myself that the aircraft stuff or butted 4130 is just dandy. I also have a long list of recipees for the clydesdale crowd. Most are taken from Frameforum discusions. A lot of those are now in the archive. Searching threads for clyde, or 250 pound will turn up some gems.