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The Official Iron Horse Sunday / DW-Link Tech. & Tuning Section

S.K.C.

Turbo Monkey
Feb 28, 2005
4,104
24
Pa. / North Jersey
(*A door creaks open... light pours into a pitch-black room... a figure appears in the doorway*)

(*the figure steps in, the door closes then total darkness*)

(*footsteps are heard followed by the sound of a person tripping over a metal bucket then falling down a flight of stairs*)


OW...OW... sonofa...

...Mother of GOD it's dusty in here.

(*turns on lights*)

Hey everyone!

Jesus - I haven't been here since the summer of 2008? No wonder I can't see the entrance any more - it's covered in ivy... someone really needs to trim these hedges... and the cobwebs.... and what's with all of these empties of PBR?

OK, so either I've been spending too much time alone on the internet, or the jpegs of info I posted here during the last presidency have degraded in quality due to site upgrades...

I will re-post and reorganize the info and try to condense things to make searching more expediant and useful.

For example: Need a new lower link, or the hardware to mount it?

sha-ZAAM: http://www.mountainbikecomponents.co.uk/items.asp?CategoryID=387&Name=IRON+HORSE+Linkages+and+spares




Me (S.K.C.) - U.S. Open 2007:







UPDATE: 02/11/08
Linkage Kits AND Vivid Compatible Lower Links are IN:

Pricing for the Vivid Compatible Lower Link and the 08' Linkage Kit are as follows:

08-Sunday Lower Link (Vivid Compatible): $55.00 USD

08 Sunday Linkage Kit (Includes Lower Vivid Link): $275.00 USD
UPDATE 1/25/08 - from now on email Carl E. at Iron Horse for info regarding the linkage:

Any questions give us a call 1(800) 645-5477 or you can email: CarlE@ironhorsebikes.com

Carl E.
warranty/tech support/CS

How to Check Suspension Sag:
http://www.pushindustries.com/support.php














Sunday Measurement Specs (ALL Model Years):
Seat Post Diameter: 30.0mm
B.B. Width: 83mm
Rear Hub Width: 150mm
Rear Axle Diameter: 12mm Proprietary Thru-Axle (comes with each frame)
Head Tube Length: 127mm
Chain Guide Mount: ISCG 05'
Chainline: 57.5mm
2006/ 2007 DW-Link Hardware & Torque Specs:

All measurments in Newton-Meters



*Note:The 05-06 7POINT uses different chainstay hardware, so torque spec is 3.7N*M on the 05-06 7POINT rear chainstay pivot.
-dw (Dave Weagle)

2007 Sunday Schematics Exploded View w/ Part #'s and Torque Values

I.H. Sunday Geo. - all model years
Geometry
Size-HA-SA-EFF TT---CS-----WB----BB
16" 65 64.5 22.5" 17.25" 44.25" 13.9"
17" 65 64.5 23.5" 17.25" 45.25" 13.9"
19" 65 64.5 24.5" 17.25" 46.25" 13.9"

Legend: HA= Head Tube Angle, SA= Seat Tube Angle, EFF TT= Effective Top Tube Length, CS= Chain Stay Length, WB= Wheelbase, BB= Bottom Bracket Height

05'/06' Iron Horse Sunday Frame Descriptions:
The Team & World Cup are identical. Both frames use 6061 alloy & triple butted tubing.

The Factory frame uses 6069 tubing with a different toptube butting profile, down tube butting profile, & chanistay alloy. It weighs slightly less, & is USA made.
-dw
06' Frame Types:
Sunday Factory (frame)
origin = USA
colors = blue, black, yellow, white, red, ano black
shocks = Progressive 5th 5-way coil, Fox DHX 5.0 coil (avail after New Years 06')

Sunday World Cup (complete)
origin = Taiwan
color = Monster Green
shock = Fox DHX 5.0 coil

Sunday Elite (complete)
origin = Taiwan
color = metallic dark grey
shock = Fox DHX 5.0 coil

Sunday Team (complete)
origin = Taiwan
color = sand black
shock = Progressive 5th 3-way coil

-ska todd
07 Frame Types:
Note: 07' World Cup & 07' Factory frames are identical.

All 2007 Frames:
- New forged 7075 links top and bottom.
- Lighter forged uprights
- More chain guide clearance on the uprights.
- Bolt in-main pivots.
- 10mm self aligning shock hardware & a pretty cool way of tightening the lower shock pivot as tight as you want.
- New graphics and stronger paint.
umm I think thats it.
-Dave
Sunday WC (complete)
Origin = U.S.A.
Color = Monster Green
Shock = Fox DHX 5.0

Sunday Team (complete)
Origin = Taiwan
Color = Black Diffusion
Shock = DHX 3.0

Sunday Elite (complete)
Origin = U.S.A. - frame built here but shipped to Taiwan for assembly as a complete, hence "Taiwan" sticker on BB -
Color = Espresso Brown
Shock = Fox DHX 5.0

Sunday Expert (complete)
Origin = Taiwan
Color = Black Diffusion
Shock = Fox Van R

07' Sunday Factory Frame Info:
Colors: Monster Green, White, Espresso Brown, Pink, Worlds Gold (limited edition)

- Made in U.S.A.
- 0.9 lbs lighter (than 06' Taiwan made frames)
- Totally new 6069 triple butted tubing.

Iron Horse Shock Hardware Info (All Models):
 
Last edited:

S.K.C.

Turbo Monkey
Feb 28, 2005
4,104
24
Pa. / North Jersey
Suspension Tuners:
Tim Flooks @ TF Tuned in the U.K. : http://www.tftunedshox.com/

Darren Murphy at PUSH in the U.S.A. : http://www.pushindustries.com/

FoxRacingShox Contact Info Worldwide: http://www.foxracingshox.com/fox_tech_center/service.htm

In the U.S.A.:
FOX Factory, Inc
tel: 831-768-1100
Toll Free: 800-369-7469
fax: 831-768-9312
mtbservice@foxracingshox.com
Q&A Sunday DHX Shock Adjustments by dw:

Some Questions For You:

1) I was thinking of going to a 350# Ti spring, but I wanted to have the most supple travel and small bump sensitivity possible w/o bottoming out (I race a lot). Would this spring rate be too high?

Ans: At your weight, you could probably go with either a 300 or 350. I think Heikki Hall is running a 300 still, and he is about your weight. If you are having bottoming problems, then you may want to explore the 350 and see how it works for you. More spring will let you use less damping to try to control the wheel. It’s a balance that is not the same for every rider's style, but typically you want to go for the lightest spring possible without huge bottoming problems. You can try a 5th bottom out bumper like Dave suggested too. That may work well for you.

2) You were saying I could run the Bottom Out at 100% turned in and this won't effect small-bump sensitivity? So maybe I could stay with a 300# spring, decrease the pre-load and run the Bottom Out at 100% ??

Ans: The 06' Development League ("The D.L." - Lars Tribus, Dave Smutok, Len Hornidge) and I spent a couple weeks in Whistler evaluating shocks and dialing in tunes on all of the 07 bikes this summer. We found no noticeable decrease in small bump sensitivity on the Iron Horse tune shocks with the bottom out cranked all the way in. I actually had a prototype shock that went 5.25 turns in, the black hex was 2.5mm indented from the face of the blue cap, and it felt unreal. Who knows what the valving inside is...

With a DHX and an 06-07 Iron Horse tune on Sunday and 7POINT, crank that bottom out all the way closed.

Bottom out shouldn't affect preload, only ProPedal will affect that, and not too much.


3) Since I'm switching to Ti, will this effect the "observed" spring rate that you feel when you ride it? In other words if a steel and Ti spring are listed as the same spring rate, will the Ti feel more progressive due to material or spring winds? (Maybe not necessarily your area of expertise, but I'd be interested in your take on it)

Ans: Spring rate is identical with ti and steel. Spring rate is a measurement of force/distance. The difference in spring WEIGHT and unsprung mass equates to about the same difference as removing the 18T cog only from your rear cassette.

4) Once I have the linkage torqued to spec. what will give me the best small bump sensitivity? Low spring rate, low air pressures in the reservoir, zero to 2 clicks of Pro-Pedal, or all of the above?

Ans: The DHX and 5th respond differently to tuning. Correct spring rate and the correct internal shock tune are going to make the biggest difference. Everything else is tuned to flavor. Start with my baseline and work from there. This will give you a good indication if you need to go with a stiffer spring etc.

Hope this helps.

Dave
DW-Link & Standard "Stock" Shocks Explained (Long Version ) :
Many shocks on the market are actually incapable of attaining damping rates low enough to take advantage of the traction and efficiency advantages of the system's full potential. (Progressive, Fox, and Avalanche have verified Shock tunes currently) If you try to use a stock "off the shelf" DHX (or most other shocks) on a dw-link, the result will be a bike with too much compression damping.

Most (off the shelf) shocks use higher spring rates and increased damping to achieve the identical performance under acceleration that the DW-Link achieves. The DW-Link Sundays and 7POINTs run 1/3 of the compression damping (EDIT: this data is for Progressive 5th Element ONLY) of any other bike on the market that I am aware of today.

The dw-link bikes come (from the factory) with shocks that are specially tuned to have less compression than that of a stock DHX. This basically means the shock has much less low-speed compression (Propedal) than the stock design.*

*Note: Any suspension will need a little bit of low speed compression, but over the last few years, the vast majority of suspension systems have been using massively excess amounts of low speed compression to mask suspension performance deficiencies in some designs. (With a stock shock) you really start to feel the adverse affects of this "extra compression" tactic at the limits of traction (with the dw-Link).
DW-Link Info:http://www.dw-link.com/home.html

DW-Link Instant Center Explained by DW:
Originally Posted by brittmtb
I was looking at dw-link.com and the location of the instant center and was wondering why placing it behind the front wheel is ideal. It seems that perhaps the bike would feel more stable having the wheel rotate about a point somewhere in the middle near the center of mass. I’m curious how different placements of the IC would effect the feel of the bike.
Instant center location ONLY effects braking performance. Moving it will change how the bike reacts to rear brake input.

Instant Center is NOT a pivot point, not in the same sense that a single pivot point can be envisioned.

Dave
Sunday DW-Link Leverage Ratios Explained by DW:
Cannon:

Hi Dave, I just looked at the Sunday kinetic in linkage and wonder why the Sunday is digressive.
If you look at the leverage ratio 1:3.05 in the beginning, in the middle 1:2.6 and from 110mm travel raises the leverage ratio to1:2.95 so the rear end is digressive from a little bit more than half of the travel.
The normal way is to engineer the suspension that it gets progressive at the end to prevent bottoming out, why do you go the other way?
Where is the advantage to the progressive linkage?
Please explain why you did it that way because I’m very curious about that.


DW:

Hi Cannon,

This was discussed in detail years ago on the board. Not sure where that info is. First off, the leverage rates that you mention in your post are totally inaccurate. The Sunday leverage rate curve is much flatter in the end of the stroke. It starts above 3:1, and stays between 2.5 and 2.6 through the end of the travel. If you look at the curve next to the curves of many other bikes it will look mildly progressive in the initial travel, and flat in the end. This leverage rate curve is tuned to the dw-link anti-squat curve. They work together to provide the best possible traction with the least possible wasted energy. The leverage rate curve is designed with the specific shock in mind. It makes a lot more sense when you look at the wheel rate curve as opposed to the shock rate curve. When you couple that with a force-output rate curve taken off of your damper, then you really get an idea what the bike will do on the trail. Basically the rates are designed with the shock in mind. On the 5ths we used the platform as an end travel ramp up (like Curnutt originally intended) and the same with the DHX and other 4-way type shocks.

The FlyinFatMan:
Yeah, one thing I've always wondered as well. I mean the current crop of mass-produced shocks (DHX, 5th, Swingers etc) are all progressive to some degree, but they're not so progressive that they make up for a falling-rate design IMO.

Sam Hill commented to me about the very first Sunday proto (the one where the lower shock mount was ON the lower link, not concentric with the pivot) saying that it "ramped up nice" at the end of the travel. Whether or not that was just his initial impressions or if that bike really was particulary progressive I don't know, but it's definitely interesting to see that the production bikes are somewhat regressive (that's the word you're looking for Cannon - but your English is otherwise excellent ).
Fatty, the original prototype Sundays had a flatter curve in the early travel, but it was too flat and didn’t let the dw-link work to its full potential in that embodiment. Much different than the floating shock setup on the IF bike though. The amount of rate change in the end of the Sunday travel realistically can only be defined as flat. Variations in machining inside the damper will have a bigger effect on performance than the amount of rate change in the end of the bike's travel. It’s a non-factor.

Take the bike for a ride and you can see what I mean. You guys can read more at dw-link.com

Dave

===========================================

Posted by WheelieMan
Although I realize that the leverage rate graph/animation at the website is not a depiction of the Sunday's actual leverage rate and is intended to be a graphical representation rather than concrete technical data, I do find it interesting that in "stage 3" the leverage ratio seems to begin increasing, indicating a regressive rate.
You got it with the highlight. Think air shocks on XC bikes. A Sunday leverage rate curve and an Azure curve are each tuned for the specific application and, and specific shock technology. Like I said before, you look at the leverage rate curve next to one from other bikes and it looks like a straight line. It is zoomed in on the curve to show detail. The amount of end travel progression or regression is tuned to meet the spring type and damper type.

The stuff on the dw-link site was done in Adobe Illustrator and Flash to illustrate the point.

The real proof is in the ride. If it makes you smile it worked.

-dw

===========================================

hi dave,

Originally Posted by dw
First off, the leverage rates that you mention in your post are totally inaccurate. The Sunday leverage rate curve is much flatter in the end of the stroke. It starts above 3:1, and stays between 2.5 and 2.6 through the end of the travel.
Can you explain a little bit, how this can be?

shock and upper link draw an angle of ~60° at the beginning and >120° at the end of stroke. so how can this linkage be progressive to flat?


DW:
The top link does not move at a constant velocity as the wheel increases in travel at a constant rate.
 

dG video

I blew a mod to get this title
Feb 25, 2004
2,131
0
vermont
Heres a question.

I have a 2006 Sunday WC. If I paint it myself, or have it done professionally will it void warranty?
 

Bicyclist

Turbo Monkey
Apr 4, 2004
10,158
1
SB
Heres a question.

I have a 2006 Sunday WC. If I paint it myself, or have it done professionally will it void warranty?
Have to send it to Class Act Coatings in Portland, otherwise it's voided. That's my understanding at least.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
AHAHAHAHAHA

That is really damn funny. Thanks man.

Damn, I type a lot....
 

DHDror

Monkey
Feb 7, 2005
181
0
Israel
I think this information is important to many
On my 05 Sunday with a 5th shock , I would like to replace both upper and lower shock mounts + reducers with the most updated hardwere version but I am not sure the local IH dealer knows the correct part numbers .

Is there a part No. chart I can chose the parts I need from ?
IH part No. for 5th shock reducers ?
IH part No. for 5th latest generation shock pins ?
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
I think this information is important to many
On my 05 Sunday with a 5th shock , I would like to replace both upper and lower shock mounts + reducers with the most updated hardwere version but I am not sure the local IH dealer knows the correct part numbers .

Is there a part No. chart I can chose the parts I need from ?
IH part No. for 5th shock reducers ?
IH part No. for 5th latest generation shock pins ?
As far as I know there is no Iron Horse part number for the 2005 shock reducers because these parts are sourced from Progressive Suspension. The 8mm reducers should have an 8.00mm hole. They are 23mm wide in 05 and 06. That's what I can lend.

Dave
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
Shock and hardware sizes:

2005 Sunday:
shock: 5th element coil, dw-link light compression tune
size: 9.5X3.0
hardware: 23 width X 8.00 ID top and bottom

2006 Sunday:
shock: FOX DHX 5.0 coil, dw-link light compression tune
size: 9.5X3.0
hardware: 23 width X 8.00 ID top and bottom

2007 Sunday:
shock: FOX DHX 5.0 coil, dw-link light compression tune
30 width X 10.00 I.D. top and bottom
 

Eggzoi

Monkey
Jan 6, 2006
161
0
Australia
Are the DHX and 5th the only shocks that need retunes to work on the Sunday? Could we put a stock ROCO or a Double Barrel on for example?
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
Are the DHX and 5th the only shocks that need retunes to work on the Sunday? Could we put a stock ROCO or a Double Barrel on for example?
Lars tried to get the double barrel tuned on his 06 bike, couldn't get it right, but I think we can get that shock to work stock. I haven't tried to tune it myself.

The ROCO and Avalanche Chubie both require a low compression tune.

Dave
 

S.K.C.

Turbo Monkey
Feb 28, 2005
4,104
24
Pa. / North Jersey
DTLogic, and dw: Just added the Progressive 5th Element info to the first page. It's a bit more in-depth and has some values you can play with for a baseline set of adjustments.

:biggrin:
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
sorry to ag it on...so am i correct in assuming that the '06 factory frames are the same as the '07's minus the new linkage and paint?
read the first post, about 3/4 of the way down. All new frame in 07.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,944
0
MV
word....it just sounds like the '06 factory frame discript.
07' Sunday Factory Frame Description:
Quote:
- 0.9 lbs lighter (than non-U.S. made frames)
- Totally new 6069 triple butted tubing.
- New forged 7075 links top and bottom.
- More chain guide clearance on the uprights.
- Bolt in-main pivots.
- 10mm self aligning shock hardware and a pretty cool way of tightening down the lower shock pivot as tight as you want.
- New graphics and stronger paint.
 

S.K.C.

Turbo Monkey
Feb 28, 2005
4,104
24
Pa. / North Jersey
For paint and frame descriptions please read the first page - everything you need is there.

As far as weight difference between the 06' and 07' Factory frames, I'm pretty sure it is very minimal.

DW might know a more definitive answer, than I can give here...

Hope this helps.

:biggrin:
 

Bicyclist

Turbo Monkey
Apr 4, 2004
10,158
1
SB
i did look through the treads. i cant find any true answer about the paint.
and sorry for asking the ? about the country
I answered it already. You need to send the frame to Class Act Coatings in Portland if you want to retain your warranty.
 

S.K.C.

Turbo Monkey
Feb 28, 2005
4,104
24
Pa. / North Jersey
i did look through the treads. i cant find any true answer about the paint.
and sorry for asking the ? about the country
Sean - no problem. Since you didn't say where you were from I think everyone just assumed you were from the States.

Class Act Paint and Powder in Portland Oregon is your best bet. Their prices are reasonable and their work is excellent.

If you are going to be mailing in your frame from another country, contact Dante(goes by this name on RideMonkey) at Iron Horse to get in touch with Class Act. He should be able to help with hooking you up.
 

Demomonkey

Monkey
Apr 27, 2005
857
0
Auckland New Zealand
I've just purchased an 05 Factory frameset. Is the seatpost size still 30mm? I had an inkling that it was 31.6mm and have purchased (not yet received) a 31.6 post. I now have this distinct feeling of impending doom after reading the specs above.

Somebody please put me out of my misery and confirm seatpost diameter specs for an 05 Factory. If i've f**ked up I can probably avoid the purchase.

Thanks in advance.
 

dante

Unabomber
Feb 13, 2004
8,815
8
looking for classic NE singletrack
it's 30.0.



I've just purchased an 05 Factory frameset. Is the seatpost size still 30mm? I had an inkling that it was 31.6mm and have purchased (not yet received) a 31.6 post. I now have this distinct feeling of impending doom after reading the specs above.

Somebody please put me out of my misery and confirm seatpost diameter specs for an 05 Factory. If i've f**ked up I can probably avoid the purchase.

Thanks in advance.
 

kieram

Chimp
Sep 13, 2006
23
0
sorry if its been posted, didnt see this anywhere.
im 6'1 should i go for the 17" or 19" frame?

cheers
 

Eggzoi

Monkey
Jan 6, 2006
161
0
Australia
Although this info is somewhere on the board seeing that this is the Sunday tech info thread, how does one remove the shock? Do the cranks/ring need to be removed. On the left there is just some strange bolt thing whereas the driveside has an proper head. Also, my shock hardware keeps coming loose up top, how do I stop that?