Author Topic: The Shiny New AM831 Group Buy (A) Thread!  (Read 173539 times)

riding_truckee

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #465 on: September 02, 2021, 08:12:21 PM »
Anybody else posting their build pictures?
Somebody else must have built by now!

BTW, I did a couple of rides on this bike (40km, 1200m of elevation in total) and I'm pretty impressed:
  - relatively efficient on the way up
  - handles well on steep downhill
  - it is easier to handle in tight spots than my LCFS947 (Lightcarbon), even though the geometries are very close.


riding_truckee

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #466 on: September 02, 2021, 09:59:40 PM »
Somebody asked about sitpost insertion length: my "S" frame only had about 13.5cm, measured from the edge of the sitpost's tube, not from the actuator.

Looking down the sit tube, it appeared as if the insertion should have been much longer: the tube was open all the way down to the shock mount.
Upon further inspection, I noticed what was stopping the sitpost: the top part of the sit tube has an inner carbon tube, which is the one where the sitpost slides, the same that is squeezed by the clamp.
This inner tube is somehow epoxied to the outer tube, which is part of the frame. The epoxy a the bottom of the inner tube bulged out in a few spots, reducing the diameter.

I decided that this was an unintended side effect of the assembly process and that it was not structural, hence I proceeded to painstakingly file down the bulging epoxy. This resulted into close-to-infinite insertion length :)

You should probably not try to do the same, unless you are sure that my "it is non structural" assumption is correct..
..but if you do, the best way I found to get it done is to tape some sandpaper to the bottom of a tube with a smaller outer diameter than the sitpost, say 25mm.
It is also useful to mark the "sanding tube" at the proper insertion length, to prevent sanding away anything else by the protruding epoxy: enlarging the sit tube diameter would probably be quite bad.

geekbox32

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #467 on: September 04, 2021, 09:32:25 PM »
After being out of town, waiting for parts, and finding the time. I was finally able to finish the build up today. Hopefully I can get it in some dirt soon.

xtinction

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #468 on: September 05, 2021, 03:43:08 AM »
Hi guys has anyone used a 210x55 shock?
Is there any saddle buzz at full compression?

riding_truckee

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #469 on: September 05, 2021, 02:27:42 PM »
After being out of town, waiting for parts, and finding the time. I was finally able to finish the build up today. Hopefully I can get it in some dirt soon.

Looking good!
Only missing the matching valve cap in the rear :)

FlaMtnBkr

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #470 on: September 05, 2021, 03:18:13 PM »
What chain line is everyone using or planning? Has anyone gone with 52mm yet? What size chainring did you run and how much clearance between the chainstay?

I jumped on a boost crank that was in stock thinking it was the right option for the boost wheel spacing but it's a 55mm chainline instead of 52mm so I'm not sure why it's labeled as a boost crank? Wondering if I should get a different crank or if spacing will be tight and the wider chain line is better...

FlaMtnBkr

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #471 on: September 05, 2021, 03:18:42 PM »
Hi guys has anyone used a 210x55 shock?
Is there any saddle buzz at full compression?

I imagine most everyone is using a 210x55 shock, as that is the size specified. Did you mean a different size or is there a reason you think there might be clearance issues?

cybrsrce

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #472 on: September 05, 2021, 03:37:43 PM »
What chain line is everyone using or planning? Has anyone gone with 52mm yet? What size chainring did you run and how much clearance between the chainstay?

I jumped on a boost crank that was in stock thinking it was the right option for the boost wheel spacing but it's a 55mm chainline instead of 52mm so I'm not sure why it's labeled as a boost crank? Wondering if I should get a different crank or if spacing will be tight and the wider chain line is better...

Sounds like a super boost chainline.  I'm not sure about other brands but SRAM uses the same spindle for non-boost, boost, and super boost and the direct mount chainrings have the offset. I jumped on a super boost GX Eagle crankset for the same reason but I was going to swap out the 32t ring for a 30t anyway. 

xtinction

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #473 on: September 05, 2021, 10:24:22 PM »
I imagine most everyone is using a 210x55 shock, as that is the size specified. Did you mean a different size or is there a reason you think there might be clearance issues?

the original hightower v2 uses a 210x52.5 shock. And according to cascade components there maybe some tyre buzz on the saddle at full compression with the saddle slammed with a 210x55 shock and their link so im just wondering would there be any issues here.

the quote below is from cascade componets website

Quote
A 55mm stroke shock (160mm of travel) can be run if desired, but for people with smaller frames or completely slammed seats, tire buzz can be an issue

JJJ

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #474 on: September 06, 2021, 02:22:54 AM »
the original hightower v2 uses a 210x52.5 shock. And according to cascade components there maybe some tyre buzz on the saddle at full compression with the saddle slammed with a 210x55 shock and their link so im just wondering would there be any issues here.

The Hightower also has a 145mm travel, whereas the FS281 has a 150mm travel.

FlaMtnBkr

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #475 on: September 06, 2021, 02:59:02 AM »
This frame is modeled after the hightower but it's not an exact copy so it's close but not exactly the same. It also doesn't have the flip chips and the cascade link changes kinematics and I think I remember is 10mm longer in at least 1 dimension so I'm sure it does change things from how the original behaves. While it's possible the seat could buzz the tire, I'm betting the specified 210x55 will work just fine.

I have most parts except for a few still trickling in and was told about a week ago it was heading to paint so hopefully will ship soon. I can try to document the build with pictures if anyone is interested? We are the first ones building it up and can hopefully help each other out if anyone has problems.

FlaMtnBkr

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #476 on: September 06, 2021, 03:42:50 AM »
Sounds like a super boost chainline.  I'm not sure about other brands but SRAM uses the same spindle for non-boost, boost, and super boost and the direct mount chainrings have the offset. I jumped on a super boost GX Eagle crankset for the same reason but I was going to swap out the 32t ring for a 30t anyway.

The super boost crank is 56.5mm, I think. But definitely bigger than 55. These are Shimano 1x12 cranks and from what I can tell the rings are the same and the cranks are different. The MX100 (where M7100 is SLX, M8100 is XT, M9100 XTR) crank is the regular crank which has 52mm chainline and for 142 o.l.d and 148 o.l.d. The MX120 crank is the "boost" version but with 55mm chainline  which doesn't make much sense as the ideal chainline for boost spacing is supposed to be 51-53mm, which the first is but not called a boost crank. The MX130 is the super boost crank with 56.5mm chainline. Anyways, if others can share what they went with and how it's working as well as ring size and clearance that would be great. It's been a while since I looked at all this and when I saw a boost crank I assumed that was the correct one and still really curious why?!

Maybe a spacer could be used somewhere to cheat things over? But will have to do some reading and mess with it once in hand. I worked in a bunch of bike shops and wrenched at races when I wasnt racing but that stopped about 10 years ago and there is lots of new stuff I haven't seen yet or at least not had my hands on. But if someone has experience or thoughts that would be great. Or at least describe what you did and how it's working so far.

Anyways, it's way too late and I'm a little delirious and probably over thinking the chainline, and definitely rambling too much...

cybrsrce

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #477 on: September 06, 2021, 06:24:04 AM »
The super boost crank is 56.5mm, I think. But definitely bigger than 55. These are Shimano 1x12 cranks and from what I can tell the rings are the same and the cranks are different. The MX100 (where M7100 is SLX, M8100 is XT, M9100 XTR) crank is the regular crank which has 52mm chainline and for 142 o.l.d and 148 o.l.d. The MX120 crank is the "boost" version but with 55mm chainline  which doesn't make much sense as the ideal chainline for boost spacing is supposed to be 51-53mm, which the first is but not called a boost crank. The MX130 is the super boost crank with 56.5mm chainline. Anyways, if others can share what they went with and how it's working as well as ring size and clearance that would be great. It's been a while since I looked at all this and when I saw a boost crank I assumed that was the correct one and still really curious why?!

Interesting, I have a full SLX setup and measured it out to 55mm as well, then I saw that it what it is supposed to be. https://bike.shimano.com/en-EU/product/component/slx-m7100/FC-M7120-1.html.  Shimano thinks 55mm is the best line for their boost gear so I wouldn't sweat the "ideal" ranges. My SRAM stuff is all 52ish but that is their boost spec ~51-53mm.
Out in the garage and took a few pictures. Today is bath day... That fiber fix tape on the SRAM setup is the reason I'm here :)  Also note, there are no AM831 frames in these pictures,  SLX is on a FE711 and GX is on FM356.
« Last Edit: September 06, 2021, 09:26:20 AM by cybrsrce »

JJJ

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #478 on: September 06, 2021, 06:40:06 AM »
The optimal chainline depends on which cogs you use most. If you do a lot of steep climbing and use the bigger cogs most, a shorter chainline may be better.

JJJ

Re: The Shiny New AM831 Group Buy (A) Thread!
« Reply #479 on: September 06, 2021, 08:25:28 AM »
Can anyone confirm the rear shock mounting hardware? 8x30 and 8x22.?