Bird Aeris owners thread

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flag Thorjensen
O+
Posted: Jan 11, 2020 at 11:04 Quote
R-M-R wrote:
The motion ratio on the AM9 is very progressive, so yes, a coil is a great choice. Or an air shock with a high-volume positive chamber and no reducers.

So on my newly started custom am9 build with a Super Deluxe Ultimate you would reccommend zero volume reducers? I'll do a proper susp anyways but I thought i'd start off with one, but now i'm leaning towards zero.

Mabey the new am9 linkage will make it more liniar and use more of it's rear travel if that turns out to be an issue.
flag Arierep
Posted: Jan 11, 2020 at 13:09 Quote
New AM9 linkage?
flag wanleggedwinston
Posted: Jan 11, 2020 at 13:37 Quote
Arierep wrote:
New AM9 linkage?
yeah they are releasing one that will make it easier for lighter riders to use the full travel I believe, presumably less progressive although someone will be able to give you a much more detailed explanation than I
flag Arierep
Posted: Jan 11, 2020 at 15:24 Quote
Didn't know that, thanks
flag R-M-R
Posted: Jan 12, 2020 at 3:05 Quote
Thorjensen wrote:
R-M-R wrote:
The motion ratio on the AM9 is very progressive, so yes, a coil is a great choice. Or an air shock with a high-volume positive chamber and no reducers.

So on my newly started custom am9 build with a Super Deluxe Ultimate you would reccommend zero volume reducers? I'll do a proper susp anyways but I thought i'd start off with one, but now i'm leaning towards zero.

Mabey the new am9 linkage will make it more liniar and use more of it's rear travel if that turns out to be an issue.

My comments have assumed the original AM9 link, which produces one of the most progressive motion ratio curves out there. If that's what you have, then yes, start with zero. I currently have no knowledge of the new link.
flag Thorjensen
O+
Posted: Jan 12, 2020 at 4:04 Quote
R-M-R wrote:
Thorjensen wrote:
R-M-R wrote:
The motion ratio on the AM9 is very progressive, so yes, a coil is a great choice. Or an air shock with a high-volume positive chamber and no reducers.

So on my newly started custom am9 build with a Super Deluxe Ultimate you would reccommend zero volume reducers? I'll do a proper susp anyways but I thought i'd start off with one, but now i'm leaning towards zero.

Mabey the new am9 linkage will make it more liniar and use more of it's rear travel if that turns out to be an issue.

My comments have assumed the original AM9 link, which produces one of the most progressive motion ratio curves out there. If that's what you have, then yes, start with zero. I currently have no knowledge of the new link.

Mounted with the stock linkage but i'm a heavy rider so could be that my weight and the stock linkage suits the ratio curve.

Here's the topic from Dan posted on the Facebook group "Bird Cycleworks Owners" the 23 sep 2019.

AM9 Owners! Recently I have been testing a new linkage that reduces the amount of rising rate in the suspension. The aim is to make the travel more usable for most riders while still retaining the "poppy" nature of the bike. If you struggle to get full travel out of your AM9 then this will probably be of interest to you. For reference the % rising rate on the AM9 is 48.5%, this linkage drops it down to 30%, which is a touch more than the 27.5" Aeris AM160.
These are about to to into production, IN THE UK, and we'll be selling them for around £100 with bearings fitted.
What I need to know from you lovely lot is what colours to make them in, and in what quantities. Please only vote below if you own an AM9 and would be seriously be interested in buying a linkage. This way I can get the correct number anodised so that everyone is happy.
flag R-M-R
Posted: Jan 12, 2020 at 4:41 Quote
There you have it. Thank you for the information.

Being a big guy does not necessarily mean you want a more progressive motion ratio curve. If a rider - heavy or light - has the appropriate spring rate and damper tune, then the need for a progressive curve is determined by the riding habits of the rider and the rider's preferred feel for the bike.
flag Arierep
Posted: Jan 12, 2020 at 5:36 Quote
48,5% of progression, that's a lot
flag rideeverything
Posted: Jan 21, 2020 at 2:25 Quote
Has anyone running a Super Deluxe (coil) on an AM9, had theirs Vorsprung Tractive tuned?
I've heard that's supposed to be one of the best things you can do for the shock

Because when riding at warp speed, all is well. But when the speeds drop it feels a little firm, certainly firmer than the Slash29 and DHX2 combo I was running previously. Now granted there are 2 things different here, different frame leverage rate, and different shock, so I can't exacly pinpoint whether it's the different kinematics, or shock tune that I'm feeling

I could put the DHX2 on the AM9 and give it a try, but I'm trying to sell it and selfishly don't want to impact the resell value (it's just come back from a complete rebuild and is like new, new reservior, shaft etc)

So what am I feeling, an overly firm stock tune on the shock? or just the inherent feel of the bikes kinematics?

Pic of my bike below because it's a looker!
photo
flag R-M-R
Posted: Jan 21, 2020 at 2:44 Quote
Do you know the tunes on these shocks? The AM9 has a lower leverage ratio than the Slash, so it will feel firmer if they both have the same tune. The Slash probably has a Mid tune and the AM9 has been shipping with Low tunes for most, if not all, of its production, so if we're comparing factory spec'd shocks, that shouldn't explain the difference.

The motion ration of the AM9 is among the most progressive on the market, where the Slash is average. A highly progressive motion ratio is associated with a very supple bike that still resists bottoming out - or, to consider the negative aspects, a less "poppy" bike that's glued to the ground and is less responsive.

Assuming the Super Deluxe has a Low tune and the DHX2 has a Mid, the difference is most likely due to the different designs and configurations of the dampers.
flag rideeverything
Posted: Jan 21, 2020 at 3:50 Quote
The RockShox is ML, can't remember which way around that refers to comp/reb though. I got it direct from Bird as the DHX2 was out of action longer than anticipated waiting on parts

The fox has the CF shim stack on the main piston but that only comes into play at very high shaft speeds

The Trek was so supple whereas the AM9 feels more taut

450 lb/in on the Trek
350 lb/in on the AM9
70 kg
flag Thick-as-a-Brick
O+
Posted: Jan 21, 2020 at 5:48 Quote
I have the RockShox Deluxe shock on my AM9. Im considering an upgrade to a used Super Deluxe Ultimate plus megneg coming from another AM9. Is it worth upgrading?

The cheep damper feels OK, but who am I to tell really, the AM9 is my first Enduro. Its definitely not as good down a rocky trail as my old 35 lb DH bike with a basic fox van, but I'm no sure if that is to expect from a 150 mm air shocked Enduro. Pedalling is awful if i use it in open mode an since my home trails are more have downhills lasting about a minute I seldom use the lever, i just leave it in the pedal mode. My old trailbike had a CCDB that I managed to tune so that it worked both up and down, Im not sure if the Super Deluxe will do that?
flag R-M-R
Posted: Jan 21, 2020 at 10:36 Quote
rideeverything wrote:
The RockShox is ML, can't remember which way around that refers to comp/reb though. I got it direct from Bird as the DHX2 was out of action longer than anticipated waiting on parts

The fox has the CF shim stack on the main piston but that only comes into play at very high shaft speeds

The Trek was so supple whereas the AM9 feels more taut

450 lb/in on the Trek
350 lb/in on the AM9
70 kg

The colours of the letters correspond to the dials on your shock. ML sequence should be red, then blue, meaning Medium rebound and Low compression. This should be fine for the AM9, if you can get the rebound fast enough.

You could probably reduce your spring rate. I'm heavier than you and I run a 350 lb/in spring, though I do have an additional position-sensitive damper. The AM9 works well with considerable sag.


Thick-as-a-Brick wrote:
Pedalling is awful if i use it in open mode [ ... ]

Interesting that our experiences are so different. Can you please further describe the climbing and what you don't like about it?
flag bansaiman
Posted: Jan 21, 2020 at 10:52 Quote
I had the same feeling some time ago. On rooty technical climbs it was like the rear wheel hung itself up on the roots and it had a great amount of pedal kickback
flag R-M-R
Posted: Jan 21, 2020 at 10:56 Quote
bansaiman wrote:
I has the same feeling some time ago. On rooty technical climbs it was like the rear wheel hung itself up on the roots and it had a great amount of pedal kickback

That's true. The AM9 has a lot of pedaling anti-squat, so the effects you describe are higher than average. This effect exists only while pedaling, not while coasting. The advantages are a more rearward axle path for better compliance and reduced squat when applying torque on the cranks.

Some people feel it's a good trade-off and other people are quite bothered by the disruption to smooth pedaling.

 


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