Egerie Aston-A-Tron - PT5 Suspension
Avalanche Suspension is something I’ve wanted to get my hands on for years—a mythical brand from the US which I’ve heard many great things about and something suggested to try out by many of my US-based followers. I’m no web expert myself, but their website looks like it was built pre-internet and is difficult to navigate. I’m also no PR expert, but email communication can be tricky too.
The product was initially estimated to arrive after 7-10 weeks but finally arrived after 16 weeks due to a delay with Avalanche receiving some parts from a supplier. It wasn’t cheap either, with the total bill coming to £3,227 / $4,110 after all shipping and taxes were paid.
However, the product has been exceptional.
Getting Started
Getting the suspension out of the box and onto the bike was easy as I already had a Boxxer installed so I didn’t need to change crowns, and the shock came with a spring and the correct hardware mounted.
The first problem was the usual one, and why I always reiterate to “find a good local tuner and build a relationship with them.” After I dialled in the base air pressure (30psi in the fork) I jumped on the bike and checked the sag, and there was too much bias towards the front, with sag being about 37% front and 23% rear. It’s easy to change the sag if you have air shocks, but more difficult with coils front and rear.
I can’t blame Avalanche for this, as I approached them with a unique bike they have no experience with - I’m guessing the main difference is the XL chainstay and not having a 70/30 weight bias on the rear wheel as per their calculations. If I were buying locally, I could have had the products fitted in their workshop, checked the sag, and left with the correct springs (or shipped a short distance instead of across the Atlantic).
Rear Shock
The rear shock is a base Marzocchi CR with the Avalanche SSD internals, chrome steel shaft, hard-coated aluminium IFP, and hybrid progressive bumper. Basically, I went with all the upgrades they offer, and it came in at $798 USD plus shipping and tax.
Keeping it simple, this shock only has spring preload plus single compression and rebound adjusters to worry about. If the shock is well-tuned to suit you and your bike you shouldn’t need any more knobs to turn. I would like to have a little more compression force (like 10% more), as I ended up fully closed, but this is probably due to the need for a lower spring rate, I tested this on the dyno and the damping was also a little softer compared to the settings I have found to work well on other shocks. This would be easily adjusted with a few shims except, again, for the hassle of shipping across the Atlantic and back.
For pure park and downhill riding, the shock has been excellent, but but nothing out of the ordinary compared to a tuned shock from J-Tech, NovyParts, NSR, or Rulezman. Part of me missed having the climb switch I’m used to on the Kitsuma to stiffen up for technical ups and road climbs. I wouldn’t get another one of these shocks personally, as it’s a lot easier to get a tuned shock from one of my locals. If I was in North America however, I would use them again in the future.
Avalanche-Tuned BoXXer
The fork, on the other hand, is mind-blowing, which is expected at $2,377 USD plus shipping and tax.
Avalanche ordered a Boxxer Select to install their custom parts. Interestingly, I asked for a Bomber 58 to match the shock, and they refused, saying it would be too stiff for my weight and recommended the smaller diameter Boxxer instead. I was never a huge fan of the Marz 58 chassis (I’ve only tested it in Fox 40 form) and it’s nice to see they don’t just sell you anything you ask for.
Image: Courtesy of Avalanche - there’s loads more interesting stuff to read on their website about this product
In this chassis, they fitted their custom open bath Boxxer Cartridge with the high-speed blow-off system (FvAT) and their hybrid coil system wrapped around it. This is part of the EFS (Equal Force System), which uses a coil spring to make up half the spring rate and the existing air cartridge at about half pressure to take up the rest (more on this later).
As mentioned, after the first setup the sag was about 37% on the fork, which was obviously silly, but I did a quick lap with the standard recommendations from Avalanche. I thought it would be nearly impossible to ride, but as soon as I dropped in, I was surprised by how much support the fork had and how it didn’t seem to wallow at all. Thanks to the huge sag, it was extremely smooth and cut through everything—I was thoroughly impressed by this start.
But the sag meant the bike was out of balance and not in an ideal dynamic position. I reduced the spring rate in the shock, achieving 30% sag at the rear, and increased the pressure on the DebonAir side of the fork to 57psi, resulting in 30% front sag. I consulted Avalanche about this, and they mentioned that while it's not perfect, they've found that this setup with Boxxer DebonAir springs requires at least 50psi due to stiction and some sagging into the travel from the negative air spring. Due to the sag issues and spring rate changes, I was probably slightly out of range from the original tune.
However, this didn't hamper the bike at all, and the fork remains the smoothest on small and medium bumps while providing the best bottom-out resistance I've ever experienced. I've never been able to run a fork with so much sag while still being rewarded with such robust support—it's nearly impossible to run any modern fork at 30% sag and still ride comfortably. You can push against it anywhere, and it holds firm. The support builds up quickly from the sag point, but there is never any harshness. You can literally ride this fork into anything at any angle, and it will plough through it. There's not much else to say, as it simply does everything you could dream of perfectly—the Holy Trifecta: suppleness, support, and bottom-out resistance.
If I spent more time on this fork, I would try to tune it to be slightly more linear at the end stroke by adjusting the spring and oil height to use a bit more travel more often, better matching the rear setup. Interestingly, it’s rare to find a fork that you know could be even better with some tweaking, but yet don't feel the need to make those adjustments because it already feels so damn good.
Having the option to run sag at the ‘perfect’ 50/50 is something I've been striving towards for a long time, and this fork made it easy. The graph from Avalanche clearly shows the overall curve of the fork: linear for the first two-thirds of travel and then ramping up over the final 30%.
Like the shock, there are few adjustments on the fork, with only rebound and single compression to consider. I finished testing and was really happy with the rebound at -14/28 clicks and the compression at -9/22.
An artists impression of the way your fork moves up and down with imbalanced pressures.
Does the EFS really work?
The hybrid coil system in this fork balances the existing air spring on one side (run at half the normal pressure) combined with a coil spring wrapped around the damper to make up the other 50% of the spring force needed.
Interestingly, in testing over the last few years, I have been using O-rings on both fork legs to check the amount of travel used on BoXXers. The standard Boxxer with an air spring always travels 2mm more on the damper side. This is due to the imbalance caused by air pressure and friction compared to the damper side. This means that the fork isn’t moving up and down in a straight line, creating more friction as the fork battles its way in an S-curve through the travel.
When we switched to the excellent NSR-tuned fork with the Race Only Springs coil conversion, this difference changed to 1mm, as the friction is lower (no air seals) and the spring rate stays the same at any speed on a coil but increases under high speeds in an air fork (adiabatic change).
This Avy fork has used the same amount of travel on each side every time I have measured it, even though I’m a little too soft on the coil spring and using extra pressure on the air side. So yes, in this fork, it seems to work exactly as it should.
This is why MX bikes use a spring and damper on each side, and why, when I have enough money, I will 100% be ordering again from Avalanche—next I will try the dual system, which puts one of these cartridge/coil combos in each leg of the fork = full moto!
How does it compare to Rulezman Dorado or NSR Boxxer setups?
This fork is the one if you just want to plough through anything and not care. A Rulezman Dorado has an overall firmer, more aggressive feel, and the NSR coil-tuned Boxxer is excellent for a finessed racer. It’s extremely hard to choose a favourite as they are all very similar in many ways and the differences come down to the bike I’m riding and the specific track conditions.
The ultimate solution could be the Avalanche dual coil system fitted into a Dorado, then fine-tuned by NSR Racing, the World Cup Wizard, or my go-to local Rulezman who knows exactly what numbers I need.
Verdict
If you are looking for something special when it comes to suspension, then you’re in the right place! If you are USA- or Canada-based, then I have no complaints at all. The hybrid coil kit was exceptional and would be a fantastic option to drop into most single-crown forks as well as DH options.
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