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Old 02-20-08, 10:03 PM   #20
Fat Boy
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Jur,

I think the ultimate problem is that you've done more suspension testing than Yan has and you're finding a lot of the limitations of such a simple design. The suspension on the Mini is for 2 things. The most important is marketing. The secondary reason is that it takes the edge off of bumps for a small tire bike.

You probably ride your Mini further than anyone else on the planet and over the most varied terrains. Ultimately, it wasn't ever really intended to do what you do with it. Not that this is that bad of an issue, but I think you're such an avid user that you are outside the normal design criteria.

So the question now is how to make it work under these conditions. Well, it's going to take some experimentation.

Judging from your tests so far here's what I've concluded:

1. The suspension alone has a certain amount of 'bob' in it.
2. The Thudbuster seatpost amplifies the problem.
3. An elastomer in the suspension has less bob than the standard spring.
4. Eliminating the suspension spring makes for more pedal bob.
5. There seems to be a certain amount of pedal bob in the 'post' part of the seatpost.
6. A softer suspension elastomer destroyed itself.

I don't know if you have access to different elastomers, but I recommend giving http://www.mcmaster.com/ a look under 'polyurethane elastomers'. They've got quite a variety and it's good quality.

Let's keep chipping away at this. Suspensions are my thing, and I'm sure we can cure this problem one way or another.
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