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Matching Chain Stay Length to Trail

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Matching Chain Stay Length to Trail

Old 05-05-19, 08:20 AM
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TiHabanero
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Matching Chain Stay Length to Trail

This winter I resurrected the first frame I built and put a new rear end on it. In the process I added 1cm to the chain stays. I like long trail bikes and this one has a figure of 67mm trail. Yesterday I gave it the first flogging, and it seemed more settled at speed, meaning it felt very stable and needed zero input to hold a line. In the original configuration the bike felt more like a mix of a road bike and touring bike, but now it feels more like an all day go bike. Not a touring bike, but a "lets go fast today" bike. Not a race bike to rail corners, but a point to point get there quickly ride.

The chain stay length is 43cm, previously it was 42cm.

My mind might be playing tricks on me, but have any of you experienced chain stay length needs to match up with the trail to get a desired characteristic from a frame?
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Old 05-05-19, 08:25 AM
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I suspect what you are feeling is somewhat due to the shift of the center of gravity between the two wheels. I also suggest care taken when trying to separate out a single factor and attribute some handling label to that one factor. If understanding bike handling was simple, a single factor or two explains all, then we'd have very few ill feeling bikes out there. Andy
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Old 05-05-19, 11:00 AM
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there are people that insist that center of gravity of the rider between the axles is very important. So if they are right, you did the right thing.
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Old 05-07-19, 05:47 PM
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Looks like I'm in for a bunch of figuring to see just exactly how that relationship is built.
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Old 05-08-19, 06:48 AM
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Ti- If you do discover the mathematical formula that anticipates a rider's perception of a bike's ride you should patent it before you mention it here or anywhere for that matter. It's worth a lot.

I use to say there were three "holy grails" in our cycling world. Air filled but flat proof tires (and that rode well), the perfect chain lube and the universally comfortable saddle. Andy
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Old 05-08-19, 06:41 PM
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There must be some relational data between chain stay length and trail (or perhaps front-center?) This needs to be explored. Not until winter, though as my plate is currently overflowing!
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Old 05-09-19, 01:02 AM
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it's pretty tricky to calculate cg given that people vary so much. Although, now that I said that, you could assume the same riding position and just vary the position of the axles.
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Old 05-10-19, 11:43 PM
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As you lengthened the CS and changed the dropouts, you likely affected the BB Drop, STA, HTA and Trail as well. Enough to notice? Probably not individually but, 10mm here, .25* there and another .25* up there all adds up. The very small changes, when added together can have a dramatic affect. The trick is knowing which small changes to make to accomplish the goals for the bike.

I'm reading a book right now about how the brain tricks itself to make sense of the world it perceives. It turns out there is psychologic phenomena that causes the body to feel what the brain thinks it should feel - sort of like confirmation bias but, different...so, who knows.

If you like it, ride it!

Happy Friday.
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Old 05-11-19, 12:47 PM
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Duane, what's the name of the book?

My daughter gets neuro feedback treatment. Her the****** said she made her triathlete sister much faster. I thought about it, because goodness knows I could stand to be a bit faster.
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Old 05-11-19, 07:46 PM
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I'm only about 1/3rd through it but I doubt it's going to make anyone any faster. It's Skeptics Guide to the Universe. There's another one called Thinking Fast and Slow that is really interesting as well. They are both popular (as in written for the people) books based on psychology, economics and neuro-sciences, they aren't scientific books though.

They both focus on how the brain jumps to conclusions, makes irrational choices and tries to understand the world around us and how our behavior and choices can be influenced in pretty predictable ways.

On the neuro feedback treatment topic, when I was racing, I had a trainer at local gym/medical center where some local national/world level athletes trained. There was some pretty cool stuff there. They had these squat platforms that shake. Apparently the jiggling platform increased the effectiveness of squats. Loads of other stuff... Very interesting.
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Old 05-12-19, 04:23 PM
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confirmation bias is a powerful thing. I feel like a lot of opinions about bike geometry are formed that way. But who has time to do double blind testing?
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