Light weight road bike

Discuss light weight issues concerning road bikes & parts.
Velozirrapt0r
Posts: 243
Joined: Thu Oct 07, 2004 7:33 pm
Location: Barcelona/Torino

by Velozirrapt0r

Itm millenium is also seen in the pro's pelloton; but I have heard that are a bit flexy (alu stem and bar), or a bit more flexy than Newton Family; but they are also cheaper. Has anyone tried Selcof carbon stems? are they reliable? And the Fsa's one? what about? they aren't the lighest out there but aren't also so expensive.
flat transitioner shimanoist

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jersievers
Posts: 1008
Joined: Wed Nov 10, 2004 4:39 pm
Location: Des Moines, IA

by jersievers

drjones96 wrote:Aluminum (metals) - Take a paperclip and bend it back and forth over and over. Eventually it will snap. You are plasticly deforming the paperclip until ultimatly it reaches the end of it's fatigue life.

Now think about a similar peice of carbon/epoxy composite. Bend it once and it's pretty much done for.


Ok take a piece of carbon/epoxy, try to bend it. Take it to a kitchen and hit it with a rolling pin, take it to the shop use to sets of plier and try to bend it, ok put it in a vise and smack it with a hammer. Get my point?

Also, AL doen't act like your steel paper clip. AL will snap just as quickly.

Read some articales about the EFB tests and look at what they have come up with about the stiffness of frames and a AL frame getting "Soft". It is in your head, frames don't get soft. Al failes like carbon does in one big explosion that you don't see coming. Have you seen someone brake a AL handle bar? It is quick and dramatic...it snaps/doesn't bend.

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drjones96
Posts: 3722
Joined: Thu Nov 04, 2004 10:56 pm
Location: Wichita, KS

by drjones96

After 4 years of engineering school I've seen my share structural testing.
I know what you're talking about though....if it has failed, it has failed...what more do you need to talk about. There are a variety of alloys though...some soft and some hard.

The harder alloys will fail similar to carbon. 6061 will bend where a harder alloy like 7075 (my wife's bars are made of 7075) will snap.

If you're interested take a look at a Stress vs Strain curve comparison for Aluminum (take your pick of the most widely used alloys in cycling) and Carbon/Epoxy composite. What you should see is the difference in the modulus of elasticity between the two (carbon should be higher) and at the top of the curve Aluminum will reach a point of ultimate strengh a while before failure. Carbon will not reach such a point before failure. That, I believe, is the diffence in the material......yeah yeah yeah....blah blah blah....engineering garbage that doesn't always apply in real world conditions.....

I'm not going to split hairs here....I think most carbon cycling components are built well enough to do the job under normal conditions. (That should include heavier riders)

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