[Udi]

infact every Ti product I've ever used has snapped/sheared (barring my shock spring... but give that time )
I don't know what a freeride tube is.
I haven't actually owned any newer Saints. I just love the stiffness and durability of Mk1s over everything I ever used previous to them so keep using them.
What do you weigh? I feel calculations may be needed here

I'm ~75kg, obviously rider mass is a factor, but some of your decisions are probably unnecessary (i.e. you haven't tried an Mk2/3 Saint set by the sounds - I can't notice any perceivable stiffness difference having owned them all - but they save a lot of weight). Between myself and heavier friends we've bent plenty of pedal spindles from crashes / impacts (mostly steel...) without any damage to those crank arms. I'd say if there's one thing you can get away with while being a fat hack, this will be it.

For whatever it's worth, the (two) Ti axle failures I've seen have both been bends, with zero shear failures. The brands I've experienced are Wellgo and Spank, both will bend before snapping. I've done one of each in 11 years - a lot less than I've bent steel axles. I've found they put up with more than chromo/steel ones (and failures have never been from regular use, only from clipping things hard) likely due to the steel ones being less than the best - so it's not a matter of strength or failure mode, but cost (as I suggested originally - you pay to play).

Maxxis make a "freeride" tube that sits between the lightweight (150g) and full DH ones (500g), they weigh 290g. Maybe not for you, but most people I know (up to ~95kg) seem to get away with them at ~23-25psi. I'd be surprised if you couldn't get away with one in the front at least.

 

[Gary]

fat OLD hack,

Thank you.

 

[Gary]

I actually thought to lighten up all my cranks a few years back but tried XTs and the amount of arm flex was plain to see while just pissing around on the hardtail they were fitted to and I knew I just didn't want that. hence riding Xc on 900g crank arms (Yeah, I'm sure I could have gotten used to the change and ignored it after a while).
With seeing newer Saints as almost exactly a halfway house between the weight of XT and my old Saints I just didn't even entertain spending the sort of money they were new on what I felt might actually be a downgrade. No doubt I could find a S/H set for pennies these days to find out for myself. will look into it.
I prefer HT Nano (grub screw) pedals to anything else I've ever tried. and I've tried most pedals (I like to ride pedals with hardly any pins so I always remove all but 5 per side (leaving just the 4 corner and a single centre edge pin) and only ever ride in normal skate shoes... I just HATE grippy pedals, always have. Their Ti spindles definitely shear and their cromo ones aren't all that difficult to bend but having bent a LOT of cranks in my time I now see a weaker pedal spindle as similar to a replaceable dropout but for your cranks
On some of our local tracks I could probably get away with an XC tube up front but there's no way I'd get my shit together and remember to switch it for a proper tube before heading up to Ft Bill or some of the other rocky tracks. It's completely irrational and I'll happily miss a few runs for BACON but even missing one run to a puncture on a DH day fucks me off more than you can possibly imagine.

 

[Udi]

Saints are not XTs. Strength is not a direct function of mass, I think you'll be pleasantly surprised.

 

[MrBaker87]

What are all you using to hack away those frame windows? I have been trying with a dremel qnd some metal cutting bits from amazon (i.e. cheap), butnthe process ismtaking forever and a day. Not to mention the bits are all wearing out faster than the frame is losing metal. I need recommendations on bits or cutting wheels maybe?

Also, I managed to buy a used RC4 on Pinkbike and got the link cut up appropriately. What are everyone's setup recommendations for the fox rc4 shock?

I weigh in circa 135 to 145lbs with a plow style. Ride steep natural pnw tracks more than anything. Currently running a 350lbs spring on my older dhx and like it just fine. Prefer stiff to plush.

 

[bengxe]

I drilled a hole at each corner and connected those with a jigsaw. Then shaped it with a file.

With the rc4 you want minimum bottom out volume and about 150psi. Lsc near open and hsc somewhere in the middle. 350 sounds about right for you. I'm about 155 and use a 400.

 

[saruti]

for your weight, (I weight like you )
you want to shim the RC4 to low tune.
then, 1 click of HSC
6 clicks of LSC
4 clicks of R
125 PSI.
300 - 350lbs spring

 

[Keen Bean]

This may have been covered somewhere in the last 119 pages but i cant see and the original model descriptions don't help so If I'm looking at old 2nd hand Sundays that have been resprayed how can I tell the year? What would be obvious things?

I've see the 10mm bolts on the 07+ ones but if its had a new top link that's not so obvious

 

[Geno]

Now its time to change my bearings.I have problems finding the original bearings which are on the dw-link.I want to ask if somebody has used normal bearings with same size and spacers (bushings) which are made on lathe.
Thanks!

 

[csermonet]

Now its time to change my bearings.I have problems finding the original bearings which are on the dw-link.I want to ask if somebody has used normal bearings with same size and spacers (bushings) which are made on lathe.
Thanks!

http://www.enduroforkseals.com/id266.html

 

[bengxe]

The proper bearings aren't hard to find. Google "6902 max e bearing" and I'm sure you'll find a source who will ship to wherever you might be. The "e" signifies the extended inner race version that you need. The lower link takes 2 6902s and 2 6903s.

 

[Gary]

if you are quick BETD in the UK are doing all their frame bearing kits at half price.
register an account and the discount is applied.

http://www.mountainbikecomponents.co.uk/bearings/mtb/frame-bearing-kits/iron-horse

 

[Geno]

Thanks Gary.I didn't know that!

 

[AllStarProject]

Selling my Medium Sunday on eBay if anyone is interested. LINK

 

[Gary]

@Udi I just picked up a set of 83x165 M815 Saints for free. like new (original owner is a mate with OCD and they never even got crank arm rub nevermind crashed, tagged on anything their entire life)
Got a new frame bearing kit to install.
Might stick a Works angleset in there.
So all going well should be be rebuilding my ol' Sunday early New year.

Paint's fucked on it so while I'm taking it apart do I get it stripped? get it Anodised? or a new durable (but heavy ) powder coat? I like BLACK, RAW is ok. Hate colours. only like subtle minimal Decals.

Here's the spec as it was when last built (41lb).

07 Sunday (small)
DHX 3.0 (3" stroke)
Progressive 2.75" stroke Ti spring
08 Boxxer Team (flat crown, stiffest spring)
E13 headset
Point1 DM (25.4)
Spank Bitch stick (25.4) - Old skool and Alu ('coz it's not Carbonz) I don't like my bars any wider see below
ODI Ruffian lock-ons - I ride gloveless, hands hanging out over the end. L-O clamps diggin' in to my palms.
Thomson post (cut down)
Madison Flux saddle - durabro! (not the lightest but rarely bend these things)
OEM IH seat clamp
Juicy 7 brakes (the last gen)
203 Avid rotors (6x steel bolts)
X9 9 speed shifter
X-O short rear mech
SRAM 950 cassette (11- 21 cut down to 7spd)
SRAM 9 speed chain
SAINT M805 83x165
HT cromo Nano pedals
36T E13 Guidering
steel crank bolts
E13 Guide - modded SRS backplate, bash removed, LG1 top guide,Home made GAMUT taco. (similar overall weight to LG1 w/taco but better mud clearance)
Hope hubs/721s/DT DB SS wheelset
Minion DHF 3C 2.5 dual ply front
DHF 2.5/Chunder 2.3/Bling bilng 2.35 dual ply rear (depending on track/conditions)
DH tubes f&r

#37 would be nice but I still don't really see how it's possible without sacrificing durability*.I don't ride DH enough anymore to justify throwing tons of cash at this but if there's anything obvious (and not stupidly expensive) please point it out.

how much weight did cutting those upright frame plates save?

My *non-durabro* avoid list
CARBONZ
Ti
I-beam
tubeless

 

[Udi]

I'm just going to pretend you aren't a grumpy old man that despises change, feel free to be open minded or shoot down my suggestions since they may involve parts invented and produced after the 18th century BC.

1. The bars are heavy and I'm pretty sure I've seen those broken - either way, for a 700 wide bar, 325g is heavy. I think you'd notice substantial performance improvements in trying a wider bar but to each their own. The Point1 DM stem is a quality product but 25.4's days are over. I run the same stem in 31.8 with Nukeproof bars (800mm) and they have been going strong for me for many years. Anything made from 7075 is a good bet and I doubt you'd break them. In 700 width a good 7075 bar should be ~250g. When you have correct width bars your hands don't hang over the ends - I found I kept doing it until I got to 800 (broad shoulders), for many people it's 750-780mm, your technique is a good indicator that your bars aren't wide enough. Keep in mind that heavier bars aren't necessarily stronger, often vice-versa since they use substantially weaker 6000 series alloy.

2. Old 203mm Avid rotors are pretty heavy (200g~), lots of modern options are lighter. The higher end Formula 203mm rotors are between 140g and 160g depending on budget, Shimano ice-tech 203mm rotors are also light.

3. I-beam saves a lot of weight w/ I-fly saddle at low cost. You shouldn't really be sitting down in DH anyway but I'm sure you broke one in the early 80s and refuse to give them a go now or something. I've run mine for years with no breaks and obviously no bends. The lightweight-but-strong-enough railed setup is generally Thomson masterpiece post and SLR-Ti saddle (not vanox, not carbon) but this stuff is silly expensive and no doubt you'd hate it anyway.

4. Could try a Maxxis Freeride tube in the front (that's what they're called, they say 280 or 290g on the box).

5. Older e13 guide is quite heavy compared to the LG1+ which I've found pretty durable and ~170g complete. No doubt you want to keep your setup though.

6. 32mm Boxxers are flexy as f. No huge weight savings to be had though, and coil is cool.

7. Paint is worth ~80g, just run it raw, anodizing has some complications and is a waste of money functionally. The frame cutouts save next to nothing, just looks cool and I found it easier to access air valve on shock.

8. The XO 9sp shifter feels WAY better than the X9 9sp, grab one if you see one pop up since I think you'd appreciate it. No weight saving, just a rad bit of kit.

9. Works cups are great, I'm a big supporter, 1.5 degrees is probably a good safe bet.

In general I don't think there's a pile of weight to be saved without irritating your set-in-stone requirements (fair enough if smashing down FW with low pressures requires DH tubes, at least you're riding a legit track), but I actually think there's a lot of modern changes you'd benefit from in terms of performance that aren't hugely weight related.

I bet you'd love a set of good ~780mm bars after a few weeks of riding to settle into them, although it'd involve finding a new stem (sadly), the width requires 31.8. If I made one upgrade to your bike this would be it. If you wanted to treat yourself, a current boxxer team would be an awesome upgrade too, the charger damper + lower friction and noticeably stiffer chassis + keeping the coil spring would be a win all round.

Bottom line - I see more potential for increased performance + enjoyment here than decreased weight.
Enjoy!

 

[Gary]

Ha ha... Quality bit of goading there Udi.

Not gonna shoot down ALL your ideas. but one or two of your preconceptions do need dealt with.

1. the spank bars are actually 715mm (I have no idea why they list them as 700) and I run my lockon's a couple of mm overhanging (with the Euro end plug trick) so the bar width actually measures closer to 720mm with grips.
I had no idea they were heavy for an Alu bar. Thanks.
I have been riding a new(ish) bike with a modern (31.8) 760mm Renthal Fatbar for the past 5 months.
long enough for me to know I need to cut them down.
Here's the thing. I like the feedback I get from the outer lock-on collar digging into the outside of my palm as it hangs over... (this is more common than you think) so in reality my hands are already as far apart as most riders on 780mm bars.
When using the Renthals my hands keep creeping inwards off of the collars... and it's horrible.
I'm not adverse to getting a new modern bar/stem combo so thanks for the pointers on which Alu to be looking for but they will still end up cut down somewhere between 740 & 720.
Where did you find the Alu series that Spank used for the bitch stick? and weights? All I've ever seen is tons of made up jargon and acronyms in their own advertising hype.

2. They're AVID G2 rotors - 180g. I had no idea OEM 203mm rotors had gotten as light as 140g. don't they warp (even) easier? Will need to look into this. I had thought I might end up switching to Shimano if I get back into riding this often enough (2 other bikes are now shimano)

3. Yeah. You guessed it. Broke both I-beams within days back when they were a new(ish) thing. No. I don't sit on them... But good tip. Have you considered a career as a skillz instructor?
I actually like SLRs a lot... too much to stick a new one on a DH bike. might well keep an eye out for cosmetically damaged ones from roadie mates.

4. Yeah. being an old skool rear wheeler I'm much lighter on the front. I can see a lighter front tube working ok for me in most situations.

5. I'm actually considering going crayzeee light on the chain device and fitting a N/W ring. top guide and some sort of ISCG direct mount Taco. I rode Ft Bill this summer on a 120mm bike (not much slower, just loads more painful) with a N/W. No clutch and no device and only lost the chain 3 times the entire day. That same bike now has a Zee clutch and a OneUpComponents top guide and the chain hasn't dropped yet in far worse situations than Ft Bill can throw at you. It's also infinitely better in mud than ANY DH guide set-up. (E-13s are all shit in proper mud)

6. After a few years on a Shiver back sometime between the neolithic and caveman era... those weedy l'il 32mm steer me just fine. I still have my 02 Monster if I ever find myself losing sleep worrying about flex

7. Cut-outs look way nicer than stock. Don't think 80g is worth rawing for weight alone (especially considering half my paint is missing already) so whatever I decide on paint wise will be purely down to vanity.

8. Yeah. I have an X-O shifter somewhere.. I don't really change gear enough on a DH bike for the feel/action of the shifter to bother me. (Ft Bill is one gear change in the first 10secs and another for the last 30... local DH I choose a gear for the day then don't even bother shifting)

9. I don't even run low pressures. I ride HT and BMX too much, hate tyre squirm and just rely on edge knobs digging in rather than tyres conforming.. it can be both slower and less comfortable but the downsides aren't enough to outweigh the performance gainz (for me)

looking like a solid 39# re-build will be fairly easily do-able and I'll bear the rest of your advice in mind whenever there's a deal on new stuff or something old dies. (Hopefully not me)

Cheers dude. yer a star!

 

[shmity]

So, i have the option of picking up an Xfusion HLR coil brand new for a pretty decent price or having an RC4 built up from parts by a shock tuner. The RC4 will come tuned for the sunday, the Xfusion i will have to take to the same guy to be tuned for the bike. What would baby jesus do?

 

[saruti]

go RC4

 

[jjperko]

Long time reader first time poster in here guys,

Anyone experienced a bit of nosediving when moving to a Sunday? Whilst with previous bikes I've had no trouble picking the bike up to clear rocks or boost jumps, the sunday seems to dive at the front when I do this.
Scrubbing or keeping it low is no problem but I'm losing the confidence to really bunny hop off lips when I need too after a couple of close calls.

I realize there might be some technique needing to be adjusted here, but at the risk of sounding arrogant I've had a fair bit of experience on other bikes and haven't had this issue before.

Are there any suspension settings/angleset or anything else I should look into?

Running a slowish rebound dhx3 with quicker 35mm boxxers.

Thanks all.

 

[bengxe]

What bikes are you comparing it to? The Sunday leverage rate is very linear which I find makes it harder to preload enough for jumps. And when you don't preload enough you'll probably get bucked forward. Do you have the right spring rates? Maybe your fork is too soft.

 

[Gary]

Running a slowish rebound dhx3

I'm no Udi. but speed your rebound up a little. NEVER been bucked on my Sunday. NEVER run slow rebound. NEVER had a problem pumping a lip.
I run my fork way harder than my rear shock too. (as alluded to above)

 

[Hambowbow]

Eeep. A lot of 27.5 sunday hate. Sooooo.....

Just bought another sunday frame, large this time, and it's going 650. No grinding, I trust the folks at IH knew what they were doing and that's just not fun, so I'm building a new rear triangle altogether. Bunch of the engineers at uni are in, mates in industrial design helping out too. End goal is to get the rear triangle as well as some headset cups to make the bike about the same geo as modern 650 DH bikes but still a sunday. Rear triangle will look pretty identical to original, too sexy to chance but have proper clearance, all the strength and same CS length, that's the difficult bit. BB height slightly lower with the slacker head angle but higher than mine is currently, it's just too low at a 62 HA.

Will be slow, no rush, still be racing the medium for a while. Front triangle will get internal routing, shed a little material to fit a float X2 but not as much as people are taking out for a vivid air and last fun bit will be grooves for the rear hub end caps to slot into for fitting rear wheel. Just for fun. Hate welcome, tell me what will work what won't, open to everything. Build will be on an aussie forum I'll link when build starts.

 

[Metamorphic]

Anyone have reach measurements for the Sunday? I am measuring 15.6" for my medium 2007, but I am no expert, so anyone else have a measurement??

 

[bengxe]

I get 16.2 to 16.4 depending on fork height for my large frame. 15.6 sounds about right for a medium if you're running a low fork height.

 

[csermonet]

I get 16.2 to 16.4 depending on fork height for my large frame. 15.6 sounds about right for a medium if you're running a low fork height.

fork height changes reach? i thought reach was measured from the center of the top of the headtube, to an imaginary line that comes up vertically from the center of the bb

 

[bengxe]

fork height changes reach? i thought reach was measured from the center of the top of the headtube, to an imaginary line that comes up vertically from the center of the bb

Right, it's the horizontal distance from the bb to the top center of the headtube. Raising the front end decreases reach but increases stack by a similar amount, so the frame shouldn't feel any smaller. I just put the numbers into this calculator: http://bikegeo.muha.cc and a 30mm increase in fork height caused the reach to shrink by 13mm and the stack grew by 9mm.

 

[szacsi72]

Hey guys! I've been looking at offset bushings for a while, and i was like why would i make my horse even lower? Then went to their website and dound this: with 3mm offset each, it will give me -1.5° HA. Which is exactly like my current works. So, in case id install offsets bushings instead of cups, it would end up with (probably close to) the same BB height as i have. And in this case, id save some money, and i could install a longer reach headset!
What do you think?

Dave teh horsey

 

[bengxe]

Hey guys! I've been looking at offset bushings for a while, and i was like why would i make my horse even lower? Then went to their website and dound this: with 3mm offset each, it will give me -1.5° HA. Which is exactly like my current works. So, in case id install offsets bushings instead of cups, it would end up with (probably close to) the same BB height as i have. And in this case, id save some money, and i could install a longer reach headset!
What do you think?

Dave teh horsey

You won't get 3mm offset from either end of the Sunday shock hardware. If you read through the last few pages of this you'll see your options for offset bushings on the Sunday. And offsets will lower the bb far more than a headset for a given head angle change.

 

[szacsi72]

Noep- i was asking if can i push the height back, combod with a headset. But no. Now, these would be bushings only. In case its too low, i can get +1cm on the front to push it back. But lets calculate it-->bikegeo.muhaa incoming!

 

[Udi]

shed a little material to fit a float X2 but not as much as people are taking out for a vivid air

The rest of what you said sounds good, but the frame really isn't going to perform at modern levels with an air shock. The Vivid Air feels absolutely terrible in these frames, and the Float X2 will still be suboptimal - the reason is that the initial leverage isn't high enough to counteract the early stroke rate spike. Have a look at the rate curve on something like the new Evil Insurgent to see a rare scenario where the Float X2 will perform near optimal levels. This isn't to endorse this frame, just an example of how air shocks still need aggressive leverage curve compensation to work well.

If you're going to all that trouble I'd run a coil shock for maximum performance with the frame's leverage curve. The thing that sets the Sunday back compared to modern frames isn't the small amount of EOS digression, it's the lack of early stroke progression. A small-shaft RC4 coil is ideal.

 

[Hambowbow]

The rest of what you said sounds good, but the frame really isn't going to perform at modern levels with an air shock. The Vivid Air feels absolutely terrible in these frames, and the Float X2 will still be suboptimal - the reason is that the initial leverage isn't high enough to counteract the early stroke rate spike. Have a look at the rate curve on something like the new Evil Insurgent to see a rare scenario where the Float X2 will perform near optimal levels. This isn't to endorse this frame, just an example of how air shocks still need aggressive leverage curve compensation to work well.

If you're going to all that trouble I'd run a coil shock for maximum performance with the frame's leverage curve. The thing that sets the Sunday back compared to modern frames isn't the small amount of EOS digression, it's the lack of early stroke progression. A small-shaft RC4 coil is ideal.

Bugger, I thought everyone was raving about vivid airs in their horses. You still on farkin? Build will be up there. Not questioning your knowledge, just want to learn some more: what about putting 11 or 12 of the volume spacers in the evol can, makes it super progressive apparently? What effect would that have, good bad? Probably give float x2 a go anyway just to see cos I'm still young enough to think I know better . In the end, if all fails sell it on and go DHX2 coil, but the orange spring isn't green, sooo.....

What would change the initial leverage? Wouldn't ever change it, love the sunday too much as is, but I'll still have my medium that eventually I'd like to mess around with the linkages and just experiment with making bikes. Hoping that's where the degree gets me. Could you link me to anything that explains in depth leverage ratios etc for suspension design, preferably bike specific?

Will start on the front triangle routing soon enough, can get spare Pivot parts easily, so all of the routing bumpers will come off a new phoenix : http://p.vitalmtb.com/photos/users/109/photos/74243/s1600_BT_20140411_untitled_shoot_015.jpg?1397314586
Same with fork bumpers. Plan so far is bumpers on down tube/gusset, down the tube then out the flat piece in front of the lower link, then not sure to go under link or over into the new rear tri, should look clean though. Chime in for anything you think, more peoples input the better.

Cheers dude

 

[Udi]

what about putting 11 or 12 of the volume spacers in the evol can, makes it super progressive apparently? What effect would that have, good bad?

"Super progressive" means little without numbers or a point of comparison. In reality air shocks all display substantial nonlinearity, with easily 50-100% increase in spring rate at the start of the stroke (compared to the linear average), even on modern air cans. The Sunday (and indeed a lot of frames) aren't designed to deal with this adequately. Dealing with it involves having a high enough leverage ratio to completely neutralise the rate increase. Since the frame's leverage ratio and air shock's spring rate both change with elapsed travel, it is possible to create a combination that works reasonably well - which is what I illustrated with Evil's trailbike curve - but the Sunday won't, and I'd just run a coil shock instead of wasting time with a known inferior setup.

Check out Vorsprung Suspension's FB page and dig through the pictures to find a comparison of air spring curves (graph I'm talking about shows a comparison of OG Fox can, EVOL Fox can, and the Corset). Once you find it, draw a horizontal straight line average across the graph yourself to get an idea of how a coil spring behaves, and then marvel at the significant difference. Then understand that throwing some spacers in an air can doesn't let you drop the pressure nearly enough to compensate for the large rate spike at the start - I've ridden the Float X2 in frames significantly better than the Sunday with maximum volume spacers and still not been particularly impressed.

This isn't what you want to hear, but the Sunday frame is nearly 11 years old - and while it was revolutionary for its time (and held an advantage for many years), that time is long gone. In my opinion going to the trouble of updating a Sunday frame is a complete waste of time, since you can buy off-shelf bikes that will be better in almost every way while not suffering the compromises that "updating" a Sunday frame will.

What would I change about a Sunday?
- Leverage curve. The lack of progression makes it feel quite dead, so it doesn't jump as well as most bikes. It also results in below-par bump absorption. The initial leverage isn't high enough to work well with ANY air shock. A newer RC4 with a small shaft is ideal for this frame because the smaller shaft cross-sectional area results in less air spring preload effect adding to the initial spring rate, while it still offers the ability to decrease the reservoir volume or even add a boost valve to add some end stroke progression. I'd pick it over a coil X2 in this frame also, thanks to a better suited compression damper + better ramp opportunities.
- Axle path. Good modern DH frames have more rearward axle paths than the Sunday, and it shows when it comes to bump absorption. Without an idler, this affects AS curves and acceleration performance, but this is a firmly secondary consideration compared to bump absorption on a DH bike.
- Geometry. BB has a tendency to dip too low when updating things like the head angle, and the lack of independent adjustment (of anything) on this frame aside from the HA makes it easy to make poor compromises. This won't be an issue with 650b however, since you'll be fighting the opposite problem.
- Chainstay length. Good for flatter tracks, but on steeper tracks there's a tendency towards rear traction loss, and converting the frame to 650b is only going to make this harder to correct.
- Seat tube length and gusset on the large is hideous, it's only human to want to change that if we're fixing the rest.
- Cable routing, which isn't a big deal to fix, but also the least of your worries.

If you do something like designing new links (to correct leverage), you'll likely create as many new problems as you'll fix. If you don't understand each output curve in detail then you won't even know which problems you are fixing and creating. Leverage, AS, BS/AR, axle path, all these curves are interdependent on this frame. With enough time and effort you *may* be able to come up with a decent solution, but in my opinion it probably won't be worth it.

By all means go ahead if you like, I'm just providing a realistic opinion. If your goal is to build something that "looks sexy" with a "sick Float X2" to people who have no idea and get a bunch of social media "likes" from the same then you'll be really successful. If this is some kind of university thesis then I'd advise against it, although it'll probably get marked politely well at undergrad level.

Just the fact that you want to run an air shock when it is clearly the inferior choice suggests to me that you're probably more interested in something other than achieving ultimate performance here - if that's the case then I'm sure the project will be a success.

Apologies for being blunt, but I personally feel if you have significant time and resources for a cool project, it'd be nice to create something that improves upon what currently exists - rather than choosing something outdated and trying to improve it to not-quite-current levels. If you have the resources to build a rear triangle and machine linkages, you can probably just build a new frame (which could be truly impressive) and use the Sunday for inspiration without being physically restricted by it.

 

[bengxe]

For riding bike park trails the lack of endstroke progression is a bigger issue than the lack of beginning stroke progression. I run an air shock to get more pop off steep lips, I don't care much about rear traction or how "plush" the shock feels. I've tried several different coil shocks on this frame and while the dampers with some progression were better than those without, none of them felt as good as an air spring. It seems to me that progressive damping doesn't contribute to "pop" as much as a progressive spring or leverage rate does.

 

[Udi]

The lack of endstroke progression is actually grossly exaggerated on the Sunday, based on inaccurate linkage graphs. We measured my personal frame on a purpose-built jig @ Vorsprung Suspension and the resultant curve showed only a very minor digression at a point in the stroke that wouldn't affect much unless you were literally bottoming out on the lip of a jump.

Numbers omitted, but the EOS leverage values stayed between 2.55 and 2.6, matching DW's claims.

I'd say your issue has little or nothing to do with end-stroke LR behaviour.

It seems to me that progressive damping doesn't contribute to "pop" as much as a progressive spring or leverage rate does.

Progressive damping actually contributes *nothing* to pop - damping is literally a dissipation of energy, so it reduces the amount of stored spring energy (i.e. elastic potential) that is returned to a rider off a lip. I do think LR curve issues are best addressed via spring rate curve (and vice-versa) rather than damping, but definitely not at the cost of adding spring curve digression at the start of the stroke.

I don't really agree that using an air shock will make it jump better either (there's a million variables here, trying 'several' coil shocks doesn't really indicate that you tried the most ideal one or the best setup), however I know for a fact that there will be losses in traction and bump absorption.

I don't care much about rear traction

Evident if you're running an air shock in this frame - not the best generic advice to give someone for DH or race usage though.

 

[bengxe]

not the best generic advice to give someone for DH or race usage though.

This is why I started my post by specifying what type of riding I'm doing. I don't race much, I've never tried to setup my bike for racing.
The coil shocks I've tried were a fatshaft rc4, vector hlr coil, and a vivid coil. The vivid felt terrible, way too much lsc. I couldn't tell a difference between the rc4 and the vector. Both were set to minimum chamber volume and minimal lsc. My air shock is also a vector hlr, and I put extra oil in the air can for volume reduction.

 

[bengxe]

Progressive damping actually contributes *nothing* to pop - damping is literally a dissipation of energy, so it reduces the amount of stored spring energy (i.e. elastic potential) that is returned to a rider off a lip.

I understand that, but I definitely felt like the progressive damped coils I've tried were easier to jump than the vivid. Maybe "pop" isn't the right word for the feeling I'm trying to describe.

 

[Hambowbow]

Snippity snip

Thanks man! Trust me I get it, heaps of people have told me I'm wasting time but like I said on RB, just trying to learn. Not actually for uni, but I've got the resources and wanna take advantage of that. As for form/function, yeah it's a bit of both but if air really won't work I'll go coil. I'd like it to perform better but also just something cool I can say I did one day. Thanks for some real input that actually helps, I'll still go a long with it all, I'll have a spare rear tri if I ever want to go back to stock 26" but I can get a Phoenix through Aus dist. pretty cheap which is the plan eventually anyway.

Cheers!

 

[bengxe]

I'd say your issue has little or nothing to do with end-stroke LR behaviour.

Maybe I should have said overall progression rather than end of stroke, but I was referring to the last half of the travel. And I'm not having an issue here, I just wanted to describe my experiences in case there are other people using their Sundays more for jumping than for racing.

 

[Gary]

I haven't raced any DH since 2004... I like jumps. My 2008 Sunday has behaved absolutely faultlessly on every jump I've ever hit with it. Infact I don't recall meeting any other Sunday owner who's had an issue with their bike's suspension when jumping. Take from this what you will.