Reynolds 853 vs cro-mo
03-11-09, 01:31 PM
#26
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How fun.
To reiterate something that should be mentioned over and over here...
Stiffness is a function of tube diameter. Period. Doubling the tube diameter increases stiffness by a factor of greater than 8. This is why aluminum bikes are "harsh", not because they're aluminum, but because aluminum bikes are often made with oversized tubes. Aluminum was developed for bikes for the purpose of making oversized tubes, for stiffer racing bikes.
"New" steels are not stiffer...they have properties that allow them to be extruded into larger diameter tubes without the walls getting too thin. I.e. 853 in 0.4-0.5mm thickness is lighter than 4130 in 0.4-0.5mm thickness. Oversized tubes in "earlier" steels are simply heavy due to the quantity of steel. With earlier steels, to get a bike as stiff as an aluminum one in oversized tubing could only be accomplished with dangerously thin tubes or at the weight of a boat anchor.
To reiterate something that should be mentioned over and over here...
Stiffness is a function of tube diameter. Period. Doubling the tube diameter increases stiffness by a factor of greater than 8. This is why aluminum bikes are "harsh", not because they're aluminum, but because aluminum bikes are often made with oversized tubes. Aluminum was developed for bikes for the purpose of making oversized tubes, for stiffer racing bikes.
"New" steels are not stiffer...they have properties that allow them to be extruded into larger diameter tubes without the walls getting too thin. I.e. 853 in 0.4-0.5mm thickness is lighter than 4130 in 0.4-0.5mm thickness. Oversized tubes in "earlier" steels are simply heavy due to the quantity of steel. With earlier steels, to get a bike as stiff as an aluminum one in oversized tubing could only be accomplished with dangerously thin tubes or at the weight of a boat anchor.
What you got wrong was "853 in 0.4-0.5mm thickness is lighter than 4130 in 0.4-0.5mm thickness." Perhaps you meant "853 in 0.4-0.5mm thickness is stronger/more dent resistant than 4130 in 0.4-0.5mm thickness."
IN fact, you are unlikely to find many 4130 tubes with 0.4mm walls - they would dent too easily.
03-11-09, 04:47 PM
#27
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Picked up my 853 off ebay for $130. The old Iron Horse frames aren't very popular. I don't think people like the graphics. Just keep looking, you'll find something nice and cheap that nobody wants.
03-11-09, 06:28 PM
#28
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I know nothing about metals but the 853 frame that I am riding is the smoothest ride that I have ever been on. The frame is a 99 Schwinn Peloton with a carbon fork that I picked up for about $150. I bought it for an everyday rider and as much as it pains me to say it, it is smoother than my Serotta with Columbus tubing.
03-11-09, 08:29 PM
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I know a tubes stiffness is directly proportional to wall thickness but what is the "power" of diameter that effects stiffness, 3 or 4? I found one reference that indicated stiffness = kD^4 and you mention it as D^3. I'm not sure my reference was correct so can you confirm what the function of stiffness with diameter is?
03-11-09, 08:36 PM
#30
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I know nothing about metals but the 853 frame that I am riding is the smoothest ride that I have ever been on. The frame is a 99 Schwinn Peloton with a carbon fork that I picked up for about $150. I bought it for an everyday rider and as much as it pains me to say it, it is smoother than my Serotta with Columbus tubing.
03-16-09, 04:07 PM
#31
Afterburners...good idea
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I know nothing about metals but the 853 frame that I am riding is the smoothest ride that I have ever been on. The frame is a 99 Schwinn Peloton with a carbon fork that I picked up for about $150. I bought it for an everyday rider and as much as it pains me to say it, it is smoother than my Serotta with Columbus tubing.
