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Old 2019-07-22, 11:26 PM   #12
leo
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Join Date: Aug 2001
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Another factor in this discussion apple/pear comparison is shape (construction) of the frame...

Quote:
Originally Posted by elpuebloUNIdo View Post
I read that steel flexes more. Given the straight shape of a unicycle frame, I'm guessing that effect is minimal.
Next 1/1/2020 I will be unicycling 25 year exactly. Some of my history of unicycles:
For 15 year I drove steel (Semcycle Pro and XL)
For few weeks I tried alloy (KoxxOne, Kris Holm, Impact)
For 10 year I drove titanium (Triton, 4x Nimbus, and my "Gino" frame).

I would dare the challange to tell blindfolded what kind of frame I ride, but for sure I can tell blindfolded when I ride a Semcycle Pro, which was designed to be flexible.
This kind of flexibility adds to riding-comfort, and makes riding circles more smooth.

A too rigid frame however, isn't comfortable. Maybe for launching a high-number-of-rev unispin, but not while being seated.

Quote:
Originally Posted by anton005 View Post
I've seen a few posts about aluminum frames failing (cracking at welds). I don't recall any posts about a steel frame failing
If you're flexible you bend,
If you're not flexible you crack.
~karate kid's master.

Quote:
Originally Posted by johnfoss View Post
For a typical unicycle frame, the major stresses are when you pedal hard, especially when pulling up on the seat/handle. Your legs put a high amount of twisting torque into the frame. I learned this the hard way when my old carbon fiber frame "failed" ... 8< ... with carbon tubing into aluminum lugs, and there wasn't quite enough adhesive down around the bearing holders.
That's one force example, but simply doing corners, with a large wheel; imagine to hold that together with your muscle-power, and probably you suddenly estimate these forces a lot stronger.
Then think of a doing pairs and a spin, or a flague. A 29'er going fast trough a slight bending road.

Quote:
Originally Posted by johnfoss View Post
Stiffer will equal higher performance.
Early '90-ies track bicyclist Urs Freuler couldn't sprint anymore when you put him on alu frames. The lack resistance (I don't call it stiffness) was transported by his muscles and nerves, and some neurologic reflex made it impossible for him to apply force. I think a Austrian university researched it, and in the meanwhile he returned to steel, returning to win 6-days track races again.

Quote:
Originally Posted by OneTrackMind View Post
One advantage of aluminium is the resistance to corrosion.
Where titanium doesn't need any anodizing for that.

I don't know the exact numbers -correct me if I'm wrong- but I think:
- alloy is more flexible than steel, but less good in returning to it shape.
- titanium is even more flexible than steel and alloy, but very rapid in going back, where the large wheel is adding up...

So for it's flexibility and strength I used it for my own frame, which has thin double tubing with the (successful) intention to make it as flexible and responsive like a spring - and strong enough for the extremer forces in pair unicycling.

Beside that I still use the Nimbus Ti. It's so durable; people still ask wether it's new (while in reality being about 10 years old). I wont be surprised the moment those will be reproduced. Or maybe they were too good.
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