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Old 03-13-12, 11:23 AM   #1
IcySmooth52
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S-Bend Down Tubes

Why do manufacturers shape them this way? What is the technical benefit? (It certainly isn't an aesthetic one!)

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Old 03-13-12, 11:31 AM   #2
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Increased wheel clearance for long travel forks.
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Old 03-13-12, 12:00 PM   #3
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I've heard of problems with toes hitting the front tire on 29ers. Don't have any personal experience with it. I personally like the traditional frames.
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Old 03-13-12, 01:33 PM   #4
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Quote:
Originally Posted by IthaDan View Post
Increased wheel clearance for long travel forks.
Almost every 29er has the head tube side with that curve, but look at the bottom bracket side. Curves so the seat tube is almost at a right angle to the chainstay and downtube. That's what makes is an "S".

Why that?
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Old 03-13-12, 01:44 PM   #5
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More weld at downtube/bb junction = stronger
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Old 03-13-12, 08:00 PM   #6
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Quote:
Originally Posted by IcySmooth52 View Post
Almost every 29er has the head tube side with that curve, but look at the bottom bracket side. Curves so the seat tube is almost at a right angle to the chainstay and downtube. That's what makes is an "S".

Why that?
Probably a multi faceted solution based around tire clearance, bottle cage access, and overall strength.

Draw a straight line from the bb shell to the bottom of the headtube and see how much closer it is to the tire, then think about fitting a bottle and cage in there. Then notice the inherent gusseting on the headtube junction, material you'd have to add otherwise.

This is an interesting topic. Perhaps a second iteration in the frame builder forum?
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Old 03-13-12, 09:04 PM   #7
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Originally Posted by cryptid01 View Post
More weld at downtube/bb junction = stronger
This.
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Old 03-15-12, 11:39 AM   #8
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Hydro-formed tubes are the new hotness.

beauty is in the eye of the beholder.
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Old 03-15-12, 04:29 PM   #9
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And, the S-bend eliminates the need for added welds and gusseting.
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