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Now Avalanche has a coil conversion kit

mykel

closer to Periwinkle
Apr 19, 2013
5,068
3,778
sw ontario canada
Have been thinking about finding a 36 in good shape and adding the Ava cart and spring for a new build this winter.

Using 2 springs of same or differing rates in combination to get various final rate for differing rider weights.
Limited to 140 - 210 lbs.

Interesting, but there must be a downside to using two equal length springs stacked.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
Have been thinking about finding a 36 in good shape and adding the Ava cart and spring for a new build this winter.

Using 2 springs of same or differing rates in combination to get various final rate for differing rider weights.
Limited to 140 - 210 lbs.

Interesting, but there must be a downside to using two equal length springs stacked.
A downside to having a spring in each leg? Not that I've ever heard. A lot the old school MTB forks had dual springs.
 

mykel

closer to Periwinkle
Apr 19, 2013
5,068
3,778
sw ontario canada
A downside to having a spring in each leg? Not that I've ever heard. A lot the old school MTB forks had dual springs.
I am under the impression that they are not separate legs, but physically stacked one on top of the other in a single leg with what looks like some type of isolater between

There are 2 spring rates and 2 springs giving 3 separate final rates

soft + soft = Rate 1
soft + firm = Rate 2
firm + firm = Rate 3

Thoughts?
 

4130biker

PM me about Tantrum Cycles!
May 24, 2007
3,882
447
I am under the impression that they are not separate legs, but physically stacked one on top of the other in a single leg with what looks like some type of isolater between

There are 2 spring rates and 2 springs giving 3 separate final rates

soft + soft = Rate 1
soft + firm = Rate 2
firm + firm = Rate 3

Thoughts?
Could be either way, I suppose. But it seems like even mis-matched springs would put less force on an arch/ lowers than a single side spring. Could be a nice way to fine tune the rate
 

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,005
Seattle
I am under the impression that they are not separate legs, but physically stacked one on top of the other in a single leg with what looks like some type of isolater between

There are 2 spring rates and 2 springs giving 3 separate final rates

soft + soft = Rate 1
soft + firm = Rate 2
firm + firm = Rate 3

Thoughts?
No, it has to be separate legs. For example he says that 24 lb/in + 24 lb/in = 48 lb/in. Which is only true if the springs are in parallel (I.e. In separate legs).
 

mykel

closer to Periwinkle
Apr 19, 2013
5,068
3,778
sw ontario canada
Could be either way, I suppose. But it seems like even mis-matched springs would put less force on an arch/ lowers than a single side spring. Could be a nice way to fine tune the rate
Ya, I guess that would work as well.
It is shown side by side, not stacked on the website.
I guess I just have compound spring stacks that have been used in vehicle coil-overs on my brain.
Hell I have no idea what I'm talking about :busted:

Either way, I'm interested in stuffing this in a 36 for a trailbike build I'm contemplating for this winter.
 
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lobsterCT

Monkey
Jun 23, 2015
278
414
2 cents regarding the Fox 40 and avalanche: I have a 17 float 40 with his damper. Earlier this year, he was willing to change my fork over to coil using fox parts and do a service for about that price.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
On the site it says you turn the air spring assembly into a dummy rod the coil spring sits on top of. There wouldn't be any uneven tension at all from having two different springs in the legs.

What I find interesting is if you go to mtbr, A LOT of people find coil sprung suspension to be a completey foreign concept.
 

HardtailHack

used an iron once
Jan 20, 2009
6,628
5,443
It probably makes the loading worse running hydraulic bottom out with two springs rather than one.
Still better than an air sprung fork with no hyd bottom circuit though.
I'd love to see how much an air sprung fork twists at bottom out on a test rig, surely RS have done it to show how beneficial torque caps are.......
 

Loki87

Monkey
Aug 24, 2008
181
146
Salzburg, Austria
What I find interesting is if you go to mtbr, A LOT of people find coil sprung suspension to be a completey foreign concept.
Same on the youtube.
They can't wrap their head around how air is not the superior spring medium :brow: and how in hell a coil sprung fork would have better performance than air because naturally air forks have more dials to play with so they must perform better. Don't even try to explain the difference between damping and spring to most cyclist.
I've had heated arguments over how a boxxer WC is worlds apart from a Boxxer Team because "it has air dampening" and "therefore is more plush"...:wait:
Also "you can't adjust coil forks" so "they're always too hard for most people" :clapping:
 
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tacubaya

Monkey
Dec 19, 2009
720
89
Mexico City
Ugh that system is pretty lame... 160mm max travel and only two spring rates (24 and 26 lb/in). You guys know these springs are usually rated with 5-10% tolerance right? That is going to cause overlaps and incorrect ratings unless Craig verifies every single one.

Also that HBO system requires a retarded amount of oil for it to work (heavy).

Not a fan, I'd much rather use Vorsprung's Smashpot system with an on-the-fly external HBO adjustment and spring rates from 30 lb/in to 80 lb/in, lower weight and cost.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
Based on the description, it looks like Avalanche is checking on the interest before they go all out on this system. As for weight of oil, my Avy'd 888 takes a lot of it. My Avy'd Fox 36 doesn't take a whole lot but I never weighed the before and after. At the end of the day, I'm too heavy for this kit anyway.
 

HardtailHack

used an iron once
Jan 20, 2009
6,628
5,443
Not a fan, I'd much rather use Vorsprung's Smashpot system with an on-the-fly external HBO adjustment and spring rates from 30 lb/in to 80 lb/in, lower weight and cost.
Is there a weight listed for the Vorsprung?
If you chop a spring in half and you double the spring rate so having two springs at half half the length of the Vorsprung's kit should make that part a bit lighter.
I doubt they would be too concerned about having a some extra CCs of oil in the fork, it would help keep the oil temp more consistent anyways and people seem to be happy to add weight to gain performance since that e-Bike article came out. A cartridge damper would have to get pretty warm after a long descent as they have almost no ability to cool inside a fork leg, you'd probably run a touch more LSC with a coil conversion too.

Do any of the coil systems use a neg spring at all?

EDIT- I'm an idiot, 350-450g.
 
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Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
Do any of the coil systems use a neg spring at all?
There is no real need for one. The only force one has to counter to start the thing moving is the friction between the seals and the stanchions and maybe the bushings. When you preload the spring that adds to it. But there is no inherent starting pressure and therefor force like on an air spring.
Some systems use a topout spring too, but that can be done by a bumper.

I've been on a Float air spring in my '15 36 TALAS RC2 for 2 weeks now and it already started to feel worse than freshly after the service and install by Fox. It was especially noticeable in the wet on slippery off camber roots. Also, when I enter my bike shed and simply push down on the fork after it has been standing there for >24 h there is a whole lot of stick slip - a thing completely unknown on my 36 Vanilla.

I really can't wait to get my hands on the Vorsprung kit. When you ride coil all the time and then ride air springs on your bike for the first time you can't believe why anybody ever would! I don't even start to talk about the air shock I rode for the first time ever since owning my Reign.

I don't care about those stupid grams anymore.
 
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HardtailHack

used an iron once
Jan 20, 2009
6,628
5,443
There is no real need for one. The only force one has to counter to start the thing moving is the friction between the seals and the stanchions and maybe the bushings.
Yeah but the wheel, tyre, CushCore, and fork lower is probably 6.5lbs and having it come to a stop without a thud makes the fork feel quite a lot nicer and makes the front end feel like it tracks better through fast rough stuff.

My current fork is able to run 180mm travel but I have it at 130mm and because it has heavy neg springs it has 30mm of negative travel but the air spring is shit and seems oddly sticky. I'm pretty sure I'll have some random fork bits that will let my try a ghetto coil conversion for my Suntour, will report back with one eye at a later date.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
I was halfway tempted to go back to air with my aftermarket piston and try the 'Runt' by Diaz suspension. Overall though, with a Fox DHX2 and Fox 36 with Avalanche cart and Push ACS3 coil, I think I added about 1.5 lbs total to the bike. Not bad I guess.
 

Electric_City

Torture wrench
Apr 14, 2007
1,993
716
How are the Avalanche carts compared to modern major OEM dampers? It's been over 15 years since I was last on an Avalanche fork.
A buddy of mine bought a new bike that was supposed to come with the Yari, but the bike manufacturer upgraded it to the Lyric for no charge because they were out of the Yari at the time. He already ordered the Avy cartridge though. I thought he wasted his money. When he brought the bike down to me to put the cartridge in I realized how huge of a difference it made just pushing down on the bar in my basement. I've been wanting to get one myself, but $400+ little too much for me at this time. We went on a ride together the following day and just watching him go across a washed out access road was impressive. The bar or his body didn't budge, but the wheel was fully active. I'll take the weight penalty for a better ride any day. The 3 rear shocks Craig did for me made a world of difference in the way the bikes handle.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,991
45
Whistler
Is there a weight listed for the Vorsprung?
If you chop a spring in half and you double the spring rate so having two springs at half half the length of the Vorsprung's kit should make that part a bit lighter.
I doubt they would be too concerned about having a some extra CCs of oil in the fork, it would help keep the oil temp more consistent anyways and people seem to be happy to add weight to gain performance since that e-Bike article came out. A cartridge damper would have to get pretty warm after a long descent as they have almost no ability to cool inside a fork leg, you'd probably run a touch more LSC with a coil conversion too.

Do any of the coil systems use a neg spring at all?

EDIT- I'm an idiot, 350-450g.
Cutting a spring in half also halves its available travel (actually less than half, since you have to now have two lots of closed/ground inactive ends), so for a given max travel & combined rate two springs are invariably heavier than one in that regard, which is why all the major manufacturers (even Marzocchi) eventually ditched twin spring systems.

Fork cartridge dampers actually stay quite cool (usually not more than 10C above ambient), because they have quite low damping force (ie little heat generated), lots of surface area, huge aluminium/magnesium heat sinks to absorb radiant heat, and they also have oil splashing over them all the time. Heat is a moderate concern for rear shocks (depending on the shock) and virtually zero concern for forks. Aeration of the damping oil however makes a considerable difference to damping consistency.

Coil spring systems usually just have a top-out spring, which is effectively a negative spring only for the first few mm of travel (however much preload is applied).
 

Bike078

Monkey
Jan 11, 2018
561
405
Same on the youtube.
They can't wrap their head around how air is not the superior spring medium :brow: and how in hell a coil sprung fork would have better performance than air because naturally air forks have more dials to play with so they must perform better. Don't even try to explain the difference between damping and spring to most cyclist.
I've had heated arguments over how a boxxer WC is worlds apart from a Boxxer Team because "it has air dampening" and "therefore is more plush"...:wait:
Also "you can't adjust coil forks" so "they're always too hard for most people" :clapping:
To be fair, and judging by pics/videos that I've seen here, it would seem that the average monkey (excluding me) rides harder, goes bigger or is more skilled than the average mtbr forum member hence the appreciation for coil and aftermarket suspension products. It also seems that the monkeys are entering middle age judging by their proclivity for fanny packs, 29ers and enduro (I have no problem with these by the way).
 

HardtailHack

used an iron once
Jan 20, 2009
6,628
5,443
Cutting a spring in half also halves its available travel (actually less than half, since you have to now have two lots of closed/ground inactive ends), so for a given max travel & combined rate two springs are invariably heavier than one in that regard, which is why all the major manufacturers (even Marzocchi) eventually ditched twin spring systems.

Fork cartridge dampers actually stay quite cool (usually not more than 10C above ambient), because they have quite low damping force (ie little heat generated), lots of surface area, huge aluminium/magnesium heat sinks to absorb radiant heat, and they also have oil splashing over them all the time. Heat is a moderate concern for rear shocks (depending on the shock) and virtually zero concern for forks. Aeration of the damping oil however makes a considerable difference to damping consistency.

Coil spring systems usually just have a top-out spring, which is effectively a negative spring only for the first few mm of travel (however much preload is applied).

Awesome, always good to see a reply from somebody that knows what they are talking about, thanks for the info on the damper, not something you can really test at home or on the trail.

I ripped my Durolux apart to see how hard a ghettocoil conversion would be, I gave up as the piston kicks sideways and binds up if you remove the seal and it needs a proper coil top cap, didn't have anything that fit in my spares box, from memory X-Fusion had a different thread so their cap won't work.

I should just hunt down a used 36 and be done with it.
 
Oct 14, 2001
67
8
Colchester, Ct
Hopefully this answers some of the questions asked above.

Coil Conversion Option

Dual Coil ABS System
Equal force system​



Description

One spring sits inside the positive air chamber using the stock air cap with adjustable preload.
The other spring sits on top of the open bath damper hydraulic ABS system in the damper leg.
The air shaft system provides the support for the spring, the o-rings are removed and air flow paths are added to defeat the air spring affect.
Top-out support is provided by a coil top-out spring inside the open bath cartridge along with the bumper in the air shaft negative chamber.

Design Goals

Uneven compression from single spring systems adds friction and causes twisting of the arch and legs.
By placing a spring in each leg with very similar rates the fork can compress without twisting or leaning to one side.
Making two shorter and thinner wire springs keeps the weight of the coil system comparable to a single stiffer long heavy wire spring.
Shorter springs compress in a straighter line reducing rubbing forces and need less maintenance replacing shrink wrap and relubing.
Hydraulic bottom out has no affect on midstroke over pressurization compared to air ramp up systems.
The hydraulic ABS and linear spring system allows for full travel on deep stroke square edged ledge and braking bumps.
Using the air spring system in conjunction with coil can create a hybrid spring system for use with heavier riders and a more progressive ramp-up if desired.


Initial Offering

Currently we are offering a limited production 2015-19 Fox 36 front fork coil conversion option available now for 160 mm travel forks and rider weights of 165-215 lbs. This is an add-on option that installs as part of our open bath cartridge and is retro fit-able for current owners of our cartridge. Dual fork springs to reduce weight and torsion when compressing. Uses standard air shaft system with minor modifications to defeat the air chamber pressure system.

Current pricing is $249 installed. Total weight of system is 340 grams. Requires ABS hydraulic bottom-out system option with cartridge purchase.

The issue for coil conversion kits is the enormous amount of inventory required to suit all rider weights and fork travel differences. Currently we are only offering 3 spring rates and travel is limited to 160 mm for riders weights of 165-215 lbs. We can custom build the cartridge for 150 mm for riders weights of 160-180 lbs.

Spring rates available:

24 lb/in +24 lb/in=48 lb/in
24 lb/in +26 lb/in=50 lb/in
26 lb/in +26 lb/in=52 lb/in

Adjustable preload 3 mm increments from 5 mm to 11 mm. Oil height adjustment from 50 mm to 70 mm damper side add progression.
ABS bottom out resistance adjustment in 3 mm increments to reduce or increase affect.

Requires minor modifications to stock air shaft piston and seal head to defeat air pressure system.

We are hoping to expand the options for firmer and softer spring rates as well as all travels of the Fox 36, Fox 34, Yari, Lyrik and Pike.

Craig