That looks like a 2009 Demo 8 II.........not a 2010.
2010 DEMO 8 BB height
- Thread starter istratetm
- Start date
You took a lot of time to analyze this article. You should read the title of the article instead of judging by the bike color.
no shuttle for the shock...
The funny thing about all this is that a 13" BB is not necessarily too low.
It is however too low on a demo which has a good bit of pedal bob and only ~12% ramp in shock rate. I smack my pedals enough on my D7 with a 13.25" bb, sub 13" must be lousy.
Maybe the next iteration will address this problem...
It is however too low on a demo which has a good bit of pedal bob and only ~12% ramp in shock rate. I smack my pedals enough on my D7 with a 13.25" bb, sub 13" must be lousy.
Maybe the next iteration will address this problem...
Low bb's are like steep head angles.....
They will kill us all....
but in all seriousness how the the ramp up affect how low the bb gets? Are you implying that with little ramp the demo will just blow through its travel on every hit?
Where do you get that ~12% figure from?
Same place as the 13.25 bb height on a Demo 7.
Well a bike that sits higher in it's travel when on the pedals (ie not a Horst linked bike, think mid high single pivot or VPP) would be less prone to bashing it's pedals given an identical BB height to a Horst link bike.
Seriously, are people just nitpicking now because they are bored or because they think it is a legit issue?
This sounds like people who just haven't ridden the bike enough to be used to the way it rides....
oh and what does the ramp up or progressiveness have to do with ride height? thats more a linkage factor the way you describe it....
AAAAAnd where was that????
You still haven't explained how that 12% change makes you hit more rocks when you pedal... Wouldn't it being .25" higher make you less likely to hit rocks.. why does it prove your point though?Sorry I couldn't remember if it was 13.25: or 13.5".
BB height:
And the 12% figure is from, well, reality.
It ramps from 3.18:1 to 2.86:1 shock rate. So that's about 12%.
The BB height point is even more exemplefied by it being .25" higher than I thought.
Whats the bb height at full compression?
how does it compare to other bikes at full compression?
Why is the sky falling?
Will the world really end in 2012?
Will it end when everyone is riding terribly designed bikes?
Atleast explain yourself when you make these statements about shock rate affecting pedals hitting rocks.....
We aren't all suspension engineers, some of us just buy a bike and ride it and dont think too much about the technicalities...
I would guess that the assumption is that a more linear frame would have a lower mean dynamic ride height than a frame with a more progressive design. At any place in the travel, a more linear rate frame will have less stored spring force (proportional to the compressive force on the bike) than the more progressive frame at the same point in the travel....or the linear frame must be compressed further to have the same spring force. The problem with this hypothesis, is that it relies on both frames having the same spring rate, and that is generally not the case with frames of significantly different average rate change.
The more progressive frame will use a softer spring rate, while the more linear frame will need a stiffer spring. The different rates are needed for both correct sag (more on a highly progressive frame) and to create the same bottom out spring force.
The more progressive frame will use a softer spring rate, while the more linear frame will need a stiffer spring. The different rates are needed for both correct sag (more on a highly progressive frame) and to create the same bottom out spring force.
All I wanna know is just where did this %12 rising rate figure come from????
Yeah that's basically the idea I'm getting at.
A bike that is less progressive will have a dynamic sag or ride height that is lower and "ride deeper in travel". Then when you add pedal bob on top of that, your pedals go smashy smashy.
It also depends on the shape of the curve, and more importantly how much the rate ramps from the sag point to the end of travel. For Example if the rate gets softer first then stiffer from the sag point, even with both bikes sagged to X%, the one with the rate that ramps the most thereafter would ride higher in travel.
PTW: Divide 2.86 into 3.18 and you get about 1.12. Hence the 12%. The two numbers I used to calculate that are from Linkage suspension program.
Oh and nothing will happen in 2012.
A bike that is less progressive will have a dynamic sag or ride height that is lower and "ride deeper in travel". Then when you add pedal bob on top of that, your pedals go smashy smashy.
It also depends on the shape of the curve, and more importantly how much the rate ramps from the sag point to the end of travel. For Example if the rate gets softer first then stiffer from the sag point, even with both bikes sagged to X%, the one with the rate that ramps the most thereafter would ride higher in travel.
PTW: Divide 2.86 into 3.18 and you get about 1.12. Hence the 12%. The two numbers I used to calculate that are from Linkage suspension program.
Oh and nothing will happen in 2012.
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ohhhhhhhh linkage...that's like real accurate an stuff
You don't seem to sure about 2012.....
So whats the height of your demo 7 at full compression?
I like Demos, i have had 3 (05, 06 and currently on an 08) the BB being lower, and the HA being a little slacker would be ideal.
The Demo is a falling rate design (so it works well with a DHX style shock) AIUI , so doesn't ramp up OR become progressive. Except withing the tuning range of the shock?
There are a ton of suspension factors that can be changed to affect how the bike rides before during and after that 33% or whatever SAG. Ever ridden 160mm bike, then ridden a 140mm bike that "just felt like it had more travel'?
I think it is hilarious that we are all arguing about a 13.5 bb height as being too much when the Team bikes have apparently been running around with 12.6 BBs.
I'll ride a Demo for 2010, a little slacker than my current, with a little lower BB sound ideal. Unless i ride a Team DH from Norco. Either way, low BB, Slack HA.
No. Like 99.9% of frames out there, it is a rising rate...and that is (one reason) why it works well with fairly linear shocks(just about all current shocks). There are VERY few falling rate frames around (santa cruz seemed to be the last hold out)...and they require a quite progressive shock in either spring rate (small volume air shock), damping (5th), or both to function 'OK'.
You are certainly correct, that set-up has a LOT to do with it...and one of the reasons that I disagree with the idea that 'more linear' bikes will always ride further into their travel. Slater touched on some of it, but there are just way too many variables in a system of bike, rider, terrain, gearing, wheel rate and its instantaneous change at every place in the travel, shock, spring, shock tuning (high and low speed rebound and compression), etc, etc.
As as a simple example, look at the frames that have highly progressive designs (older DHR, Makalu come to mind) they are recomended to and ride great at 40-50% sag. This could put the bb at static sag close to 10 inches..