- See those Bird hardtails…
Anti squat is a function/feature of any rear suspension system. Horst, Singlepivot, dual link, whatever.
It’s the propensity of the suspension to extend under power.
Inputs are chain tension and wheel thrust forces, movement of COG, angle of slope, and other things.
Bird frame interesting as seems to have a main pivot position that is in line with chainring, normal for a singlepivot bike, but with a Horst link too.
I will be interested to have a doodle in linkage to see what the graphs look like.Posted 3 years ago
@thisisnotaspoon – the geo on Dirt is actually slightly wrong (my bad but its not that wrong so I wont get them to correct it), the Bird Aeris sizing is:
380 425 445 465 490 mm
or 15.0 16.7 17.5 18.3 19.3 in old money.
And thats with a full spread of ETTs.
So I am with you 100%.
Are you the chap I met at the London Bike Show?Posted 3 years agoNorthwindSubscriber
benpinnick – Member
@thisisnotaspoon – the geo on Dirt is actually slightly wrong (my bad but its not that wrong so I wont get them to correct it)
Not going to tell you how to do your job, but, I’d get it fixed if I was you- there’s tons of us nerds out there that like numbers. It doesn’t make any real difference but we don’t care.Posted 3 years ago
Is the BB drop right?Posted 3 years ago
Jones said this had a really cool BB height, but yours is lower.chiefgrooveguruMember
Good work guys! I’m thinking 170mm cranks make more sense than 175mm for average height riders with the propensity for low BBs on modern geometry. I noticed the geo chart looking strange because the BB height was lower with the 150mm travel but the angles steeper, which is obviously the wrong way around.
Anyone curious about how suspension works, go on linkagedesign.blogspot, use google translate if you dont’ speak Spanish, and try to get your head around the graphs. It’s incredible how different the performance of two 4-bar systems can be, simply through small changes in pivot location. It’s also pretty amazing how a single pivot like an Orange 5 can be made to pedal really well – but you’re restricted with leverage rate and there’s also the issue of lateral rigidity without other linkages.Posted 3 years ago
I noticed the geo chart looking strange because the BB height was lower with the 150mm travel but the angles steeper, which is obviously the wrong way around.
No, its the right way round – on the Aeris anyhow. The sagged geo (contrary to popular opinion sagging an FS does effect its geo) is what you would expect, but the linkage positions don’t work like most bikes, you are changing the geo so it starts steeper/higher, but ends lower by a touch – more importantly its giving a different shock curve in 140 that 150. 150 is more resistant to bottoming while 140 has a longer ‘sweet spot’ where the shock is very supple in the mid stroke.
This looks smart…. What other colours will it be available in?
Tangerine Orange, Stormtrooper white, Bigfoot blue, Very Lime green and black as the night.Posted 3 years agochiefgrooveguruMember
No, its the right way round – on the Aeris anyhow. The sagged geo (contrary to popular opinion sagging an FS does effect its geo)
Yes, it’s often misunderstood! It looks like the bike sits deeper in its travel at 150mm (30% sag) than at 140mm (21%). Is that due to the leverage curve or does it require changing the shock pressure? Your charts are with 531mm A-C which I guess is with one of the 140mm forks, so they’ll be a bit slacker and taller with the 150mm forks. Geometric navel gazing… 😉 Is it warrantied to 160mm forks?
I spent a while sussing tweaking in my full sus with different pressures and settings front and rear plus three rear axle heights to choose from (Banshee) which affect BB height and angles. I like being able to have a local setting and gnarly uplift setting: A bit steeper and taller suits more twisty and pedally trails whilst lower and slacker suits point it down the hill and hold on trails.Posted 3 years ago
Right. I just need to be convinced they can be set up to be poppy.
I haven’t liked the Specialized FSRs I’ve tried because they soaked up too much energy for getting air of small trail features. Conversely, the Cotic Rocket was very lively in the same situations.
I’m hopeful that the high pivot point and progressive rate might help.Posted 3 years ago
Obviously a test ride would be ideal.fingerbikeMember
Looks like the Aeris rides good too, What Mountain Bike liked it: https://twitter.com/Bird650b/status/514330275820871680/photo/1Posted 3 years agodeadkennySubscriber
AlexSimon – Member
Bird are Taiwan at the moment
Like most bikes, including Santa Cruz. Same factory even I think.
or on one, of which I am suspicious of because the frames are cheeply priced.
Nothing wrong with their frames. The price just reflects lower margins or lower business costs. The 456 models of various forms are some of the toughest frames about. Though nothing is indestructible.Posted 3 years ago
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