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Dark Owl DXX (Fatigue testing vid page 6)

How long chainstay should be at SAG point?


  • Total voters
    53

troy

Turbo Monkey
Dec 3, 2008
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Hmm, ok I think I can do that. I will redesign the main pivot clamps + figure out how to make a new fancy cs bridge + move the whole linkage towards the front axle.

How long the CS you should be in Your opinion (at SAG point)? We have 1 idea to make it 16.9" at sag. Yay or ney? Any other ideas?
 

4130biker

PM me about Tantrum Cycles!
May 24, 2007
3,884
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Re: Ghost
Just what hell is goin on there down there? All sorts of strange connections and or pivots around the BB... Looks like a test mule more than a production thing to me.
 

troy

Turbo Monkey
Dec 3, 2008
1,008
742
Re: Ghost
Just what hell is goin on there down there? All sorts of strange connections and or pivots around the BB... Looks like a test mule more than a production thing to me.
It is their new RIOT link "technology".
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,061
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borcester rhymes
It does make sense for them to have the same system throughout their lineup, if they can...

Idlers are also viewed with a lot of skepticism by a lot of riders. A little too "2004" for many.
 

troy

Turbo Monkey
Dec 3, 2008
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It does make sense for them to have the same system throughout their lineup, if they can...

Idlers are also viewed with a lot of skepticism by a lot of riders. A little too "2004" for many.
Yeah there are some comments about the idler efficiency. I guess those are coming from Giant riders.
 

4130biker

PM me about Tantrum Cycles!
May 24, 2007
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Idlers are also viewed with a lot of skepticism by a lot of riders. A little too "2004" for many.
All the while while people clamor for less useful shit like "new" bio-pace rings and fanny packs. What's next, positron the shifting resurgence?
 

time-bomb

Monkey
May 2, 2008
957
21
right here -> .
hey ya'll, how much yaw does it have?

i know this complicates things and makes production way more expensive but have you given any thought to building in adjustable features? alutech has a nice adjustable wheelbase system at the rear axel (others have done similar things). this feature may not be that practical for a bike who's wheel base changes more so than others. another thought would be having a couple shock mounting options that allow you to easily change the bb height and head angle. side note: i like to tinker w/my set up :-)

without all the fluffy stuff i mentioned, i'd still be interested in one of these. looks rad!!
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,061
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borcester rhymes
adjustment is great, if it can be integrated cleanly. There's little worse than a dozen shock bolt holes or a screw collar that always has a small amount of play.

As for the chainstay, I think low 17s is great at sag, as you're still going to get a little growth past the sag point, maybe similar to what other bikes have. I remember BCD ran 16.7" chainstays with his 29er frame in order to get reasonable stays at sag.
 

tomasis7

stroganoff
Nov 5, 2014
623
65
Electronic bong-shed LEGAL
Awesome prototype, troy! I look forward for finished result.

I'm 510 and I find 420-440mm reach as ideal, depending on type of ride, track, stem length. Cs 440mm seems perfect for me for dh ripping on shorter front end.
 

jstuhlman

bagpipe wanker
Dec 3, 2009
16,676
13,021
Cackalacka du Nord
agree adjustability is nice. it's one of the main reasons I went with an uzzi as a do-most-stuff "one" bike over an sx trail. that said, on a dedicated dh rig it's maybe less of a concern?
 

kidwoo

Artisanal Tweet Curator
We talking chainstays now? It's funny how many people used to agree that shorter was gooder until aaron gwinn started whining about it on the demo.......ignoring the fact that the short and forward arc had more do do with those things hanging up than just chainstay length.

I'm still all about short as possible. Everyone assumes it has do with manuals or some such silly, but it changes the way the wheels get weighted. The shorter they are, the more weight gets distributed there in corners. Which is huge in corners where you're yanking the bike around with very little, if any weight on the front wheel. See recent eddie masters/reece vid for reference. Half an inch isn't huge but I'm still on the shorty ass bandwagon.

Plus they scrapey-skrub a little easier.

Like you said though, I wouldn't compromise a structural component to shorten it though. Maybe "as short as you can go, while keeping the bridge". It will also make the rear end stiffer with less of a lever.
 

troy

Turbo Monkey
Dec 3, 2008
1,008
742
Probably not that much hassle to offer two or three chain say lengths if you're building them as ordered.
For now I want to make small batches (~10-15) of frames. 1st couple of frames will go for EN testing. Rest for sale.

17.1" (435 mm) at sag sounds ok. For now no adjustable dropouts and stuff. Or maybe I will make some kind of eccentric insert with a pinch bolt, so You can adjust Your CS length and BB heigh. We will see :)
 

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,006
Seattle
Or maybe I will make some kind of eccentric insert with a pinch bolt, so You can adjust Your CS length and BB heigh. We will see :)
Don't. I had a Transition Bank with those and they were a PITA. Creaky, I had a hard time keeping them tight, adjusting the brake sucked because the axle moved, etc.
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
The ideal CS length at sag actually depends heavily on the tracks you are riding, because the biggest effect CS length has is on mass distribution over each axle and thus the F/R traction bias.

There is actually no right answer and "short as possible" is not necessarily ideal either, because on less steep tracks there's a tendency for that to make cornering (particularly out of traction corners / drifts) very sharp/snappy and unpredictable. However the same bike that might behave like that on a flatter track will become more predictable to drift on a steeper course and have more rear traction than one with longer chainstays.

I think aiming for somewhere between 17.1 and 17.3 at sag would offer a reasonable balance, in this case probably 17.1 as it will grow more than other bikes beyond sag.
 

kidwoo

Artisanal Tweet Curator
There is actually no right answer.
I agree with that, but would say it has more do do with what's going on with the rest of the bike more than the track. Every corner has crappy traction if you go fast enough.


and "short as possible" is not necessarily ideal either, because on less steep tracks there's a tendency for that to make cornering (particularly out of traction corners / drifts) very sharp/snappy and unpredictable.

"Flatter tracks with crappy traction" pretty much defines most of the long standing riding where I live and is where I came to appreciate the sharper bite of a tire further up underneath you. And yes the bikes I've owned with longer chainstays, I'd say were more suited to built up berms and hero dirt where you don't need to move around to bias one tire over the other to get it to bite.

We're most likely talking about an inch and a half defining the extreme ends of 'long vs. short' given. But I've owned some older bikes with 18ish chainstays and some specialized 16.5 things and where suspension performance isn't really involved, I definitely prefer the tire up me arse in sketchy corners, flat or not.

Either way I'd say it's a fairly minor preference. With troy's pivot design I don't see a whole lot of reason to not try and get it short. I'm only talking like at or sub 17. No one's making 20" or 14" chainstays on suspension bikes so none of us have even ridden the true extremes.
 
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vinny4130

Monkey
Jun 11, 2007
454
215
albuquerque
I like the idea of adjustable CS, but how easy it is to change makes the difference in its over all usage. My example is the v3 Commencal IMHO is less convenient than the v2, I felt the v2 allowed the bike to be easly catered to a track with a simple adjustment. The v3 had 3 settings that required the wheel to be removed and many other (brake related) small parts interchanged PITA. I also think that as the top tube gets larger to accommodate a larger rider the CS should also, but the relationship is not easy as a TT to a riders height, CS are even more of a personal preference. A shorter rider may like longer a TT and shorter than avrage CS. Or I think of it like this, a xs frame most times has the same CS length as a XL and to me that's not right. And speaking of other bikes I've had, I had great luck with the bank and thought the adjustment was solid and simple. I found that if I used two short L wrenches in the eccentric pucks it made the adjustment easier.
 

troy

Turbo Monkey
Dec 3, 2008
1,008
742
We will make 1 frame for Kamil, the framebuilder this week (or next week).

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no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
Looks like it'll eat bushes. Does it have a lot of falling rate to suit air shocks? Or is that just an optical elusion? Maybe slap a shuttle on the front shock mount to suit different shocks and ideals.
 

troy

Turbo Monkey
Dec 3, 2008
1,008
742
Looks like it'll eat bushes. Does it have a lot of falling rate to suit air shocks? Or is that just an optical elusion? Maybe slap a shuttle on the front shock mount to suit different shocks and ideals.
Actually an air shock model is there just for show, because I have no fancy 3D coil shock model at the moment. It is a linear'ish-rising rate design. Yakuza Kumicho kinda like, but more progressive through the travel.

8" of travel
idler
16.7" CS
0.7" rear axle path
44mm HT
26"
~7.8 lb on 4130 straight gauge tubing (we will use some fancy Reynolds and Columbus tubing for Kamil, and flilet braze the whole frame, so it will be much lighter)
 

saruti

Turbo Monkey
Oct 29, 2006
1,167
73
Israel
the shorter the rider, the shorter the CS shuld be.
tall riders can get the balanced over the back wheel easyier even with longer CS.
 

no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
the shorter the rider, the shorter the CS shuld be.
tall riders can get the balanced over the back wheel easyier even with longer CS.
Yeah, but, still gotta steer that boat. Length/height doesn't equal mass exactly.
More powerful and skilled riders that ride faster and/or on faster tracks will appreciate longer stays more than the rest of us. At higher speed the maneuverability isn't hindered as much. The current trend of larger mainframe to gain wheelbase length with shorter stays is pretty logical. Also a good way to cater for larger riders.
Actually an air shock model is there just for show, because I have no fancy 3D coil shock model at the moment. It is a linear'ish-rising rate design. Yakuza Kumicho kinda like, but more progressive through the travel.
Cool, just optical elusion then or my accurately my poor judgement of angles. Air shock didn't throw me, shock just looked steep, getting steeper.
 
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troy

Turbo Monkey
Dec 3, 2008
1,008
742
Hey guys! High quality, military spec., aircraft tubing for DH02 Proto finally arrived! Have to make custom tooling for tube bender, which should take around a month, and we will be ready for production! Steel is real! #ProMoly™

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troy

Turbo Monkey
Dec 3, 2008
1,008
742
A new roll bender just came in :) I'm still waiting for custom made tooling for a mandrel bender to make tighter radius bend on DH02 downtube. Stay tuned folks! Dark Owl is coming soooon! :rockout:
pudlo1m.jpg
 

troy

Turbo Monkey
Dec 3, 2008
1,008
742
I don't think I would sell many of those :( Maybe in the future I will offer it as a custom made 29er version. Right now I'm focused on making 26" DH bikes and 650b and 26" Enderpo bikes :monkeydance: Dark Owl website will be up soon :weee: