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Cromoly vs Reynolds 725

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Cromoly vs Reynolds 725

Old 05-11-19, 01:32 PM
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jambon
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Cromoly vs Reynolds 725

Hi there,

I thought this might be the best place to ask this

I am looking at 2 different frames ,

one is Chromoly steel , Kona Butted Cromoly to be exact

The other is Reynolds 725

Would I notice a difference between both materials in a blind test for example ?

If I have large tyres on low pressure will it make any difference in the ride quality from either steel become barely noticeable ?

Is their much of a weight difference between the two ?

Thanks for any inputs
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Old 05-11-19, 01:35 PM
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a cubic solid block of any steel , if exactly the same size, will all weigh the same.
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Old 05-11-19, 01:39 PM
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Without knowing the tube sizes and thickness it's not possible to predict how the two different frames will ride. However, 725 is heat treated chromoly so likely the tubes are thinner, so that frame will ride smoother. It's sort of a hair splitting exercise though.
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Old 05-11-19, 04:14 PM
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some chrome moly (usually 4130) tubes are really thick, so heavier. You'll have to be more sensitive than me to tell the difference between them, all else being equal
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Old 05-11-19, 05:01 PM
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Originally Posted by unterhausen View Post
some chrome moly (usually 4130) tubes are really thick, so heavier. You'll have to be more sensitive than me to tell the difference between them, all else being equal
A friend let me borrow his Diamondback Prevail road bike for a week one time when I was traveling in his area and didn't want to lug my regular EL OS bike with me. In comparison to my bike the Diamondback was heavier because the tubing was thicker, but more noticeable to me was the stiffness; that bike was quite stiff through the bottom bracket and the rear wheel would almost hop if I got sloppy when sprinting out of the saddle. I kind of like it truth be know. The ride was a smig rough but I put a lot of preference in a stiff bottom bracket because I hate hearing chain rub. At any rate, I just mention this because it relates to the topic of two frames of different tube thickness and how there can be a noticeable effect in the real world.
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Old 05-11-19, 06:19 PM
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how did the geometry compare though? My gravel bike is a brick, 4130. The main thing that bothers me about it is the flop. I keep threatening to make a fork for it and I finally made a mandrel to try to bend the really heavy duty Nova disc fork blades. So I might finally get around to it.

I carried it up 9 flights of stairs a couple of times. That was when I really realized how heavy it is.
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Old 05-16-19, 10:04 AM
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4130 is: %_ .28-.33 C_ .4-.6 Mn_ P(max) .035 _ S(max) .04_ .8-1.0 Cr _ Mo .15 -.25..

the numbers have meaning.... that is what 4130 means ..

Ref: Machinery's hand book Rev 23.


In addition , as said above you have also wall thickness tube diameter

and potential heat treatments and other metal working techniques ..









....

Last edited by fietsbob; 05-16-19 at 10:12 AM.
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