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Unsprung Weight and Suspension prefomence

Is unsprung weight underestimated by Enduro and Downhill riders?

  • Yes

    Votes: 2 50.0%
  • No

    Votes: 2 50.0%

  • Total voters
    4

badkar_

Chimp
Feb 21, 2012
4
0
Why is it that MotoX and car tuners take so much care to lighten there unsprung weight to improve suspension preformence and there is hardly any talk of this among mtb bikes. A MotoX rider would be very happy to save 200g on a wheel because it improves suspension. Mtb riders seems to happily add more and more to there back wheel. Now the Sram eagle is out and it adds another 100g with a heavier cassette and derailleur to the rear wheel. People also seam to happily buy quite heavy hubs for the same price as light ones for example Chris king 325g vs DT Swiss 230g.
So I got some questions.
How much difference in suspension preformence do I gain by reducing weight by 300g on a 3000g wheel? Will it be 10%, or more, or less?
Will the 250g heavier Onyx Racing hub compensate with its friction less hub design and ceramic bearings compared to a DT Swiss 240?
I would like to keep this post as much as possible to suspension related answers only.
 

slimshady

¡Mira, una ardilla!
As far as I know, reducing 100g in a wheel equals to 300g of weight reduction in the frame, because of the effect of the rotational mass. On the other hand, you can't trade the benefits of a good rim/tire combo for a weight reduction, because the overall performance will suffer.
 

badkar_

Chimp
Feb 21, 2012
4
0
Yes that it tru. But I guess you could build a lighter wheel today using a carbon rim and get a better ride. The thing I can't find an answer to is why no one talks about suspension improvement. If 300g are so important on a MotoX or car why wouldn't it be even more important on a enduro?
 

Jm_

sled dog's bollocks
Jan 14, 2002
18,855
9,560
AK
But to be serious, we already do reduce unsprung mass to the extent practical, but there are other things that are just as, if not more important. Having good tires is way more important IME, and one tire may weigh 800g while another weighs 900g. Carbon rims have shaved a lot of weight off compared to the wheels of yester-year, so we are probably significantly ahead of where we were, plus that cassette is close to the center of rotation, so less effect there. Most people do try to reduce the weight as much as they can, but the overall bike design is often going to be more of a deciding factor, such as suspension parts that you can not change. There were lots of people convinced years ago that an inverted front fork would save all kinds of unsprung mass, yet if you do the math, you'll see it doesn't save but a couple percentage points, because alu/mag cast lowers are damn light and lower-stanchions/internals/dropouts on inverted forks are not weightless, so things like those tires, rims, brakes, hubs, all add up to give you a total weigh that really doesn't change for anything with an inverted fork, relative to the unsprung mass, and if you can tell that difference, you're a better rider than anyone here.
 

badkar_

Chimp
Feb 21, 2012
4
0
Thanks for your input. Yes, I know there is a lot more going on.
Don't forget that the same radial forces apply to the suspension. The linkage move the wheel in a circle too and then the hub should matter just as much as the rest of the wheel if you look at it from this point. It is also changing direction (up & down) way more often then a spinning wheel.
I just wanted to single out suspension performance and see if someone knew how much weight affects suspension sensitivity.
 

Muddy

ancient crusty bog dude
Jul 7, 2013
2,032
907
Free Soda Refills at Fuddruckers
I just wanted to single out suspension performance and see if someone knew how much weight affects suspension sensitivity.
Yeah about that...

Illogical approach to sorting out a suspension build. No two people will have the same physiology @ a given height and weight so... the effects of unsrung (sic) weight on suspension cannot apply. Then - the rider with more torso-than-leg may have a behind the pedals riding style which as a result may have a different setup of the Fork. So, any hard-numbers for suspension still do not apply.

Really, some of the 'performance' is just from a rider, and the suspension following along.
Teh Interwebz seems to have a roll in suspension effect as of late... seams a hip thing.
Whatevs. Ride a Bike.