Doing your Archery well Oiled

CAD design image of the XM1

Occasionally, we let our editor off the leash and let him run loose on the internet. Don't worry, his monomania doesn't let him search for anything but archery related subjects and he has found some doozies. Like the crossbow with no limbs, the 5 round magazine for a compound (the Fenris) and a "golf driving simulator" for archery! When we heard him muttering about "hydraulics" and "viscosity", we did get a little worried ... but there was no cause for alarm. He'd just found another outlandish yet oddly practical archery innovation.

Todays topic is the XM1 Hydraulic Recurve Riser from Italian company Smartriser. The basic characteristics of this riser are pretty straight forward. An attractive 25" riser available in left and high hand. ILF limb fitting (as it should be - none of this hoyt formula rubbish). CNC milled from a 10kg billet of 6000 series aluminium alloy**. Custom wooden handle and anodised colour coating as befits a top end priced riser. On first glance nothing stands out from it being well-made riser from a smaller manufacturer till you get to the riser type description:- Hydraulic Recurve Riser. Hydraulic? What the hoyt!?

After a browse of the manual and a look at some pics .. the mystery of the hydraulic riser is revealed. The riser has 4 sealed carbon fibre chambers inset into the riser and filled with fluid with the aim of dampening vibrations after the arrow is shot. Pretty neat. So, let’s take a deeper dive into just what this entails.

exploded diagram of the tubs

The HFVD (High Frequency Vibration Dampening) system makes use of the laws of fluid mechanics to reduce the vibrations you feel in the riser on release of an arrow. Four sealed carbon containers called tubs are inset permanently using the riser as a frame - 2 above and 2 below the handle. How permanently? They are epoxied in using Araldite, curing for 60hrs via pressure from TORX screws using torque wrenches for correct tension. These screws are fixed in place with Loctite. This ensures the tubs are permanently attached and maximise efficient transfer of energy from riser to the tubs. Now that's pretty permanent! The total capacity of these tubs is 70cc's (70ml) and filled to 80% capacity with "technical fluid" of a high viscosity (thick, sticky, and semi-fluid). This liquid, we're assuming is some kind of silicon-based oil, dissipates vibrations post shot. These sorts of oils are effective across a wide range of frequencies or so fluid mechanics assert (editor: has anyone ever meet a fluid mechanic?) This built in weighting and vibration suppression system should reduce any hand-shock felt and provide a considerable amount of noise suppression with minimal sticky out things. Ideal for barebow even if it was originally envisaged as a normal recurve riser.

close up of the QuickClick limb bolt

There is also the addition of a system that SmartRiser call "QuickClick" to the limb bolts. This is an innovative and pretty unique system which we think is awesome. You don't need to unlock, turn and relock limb bolts when changing tillering and draw weight. Adjusting the bolts can be done with your fingers. Each 90' click of the bolt equates to +/-0.5% change in the draw weight of your limbs. There appear to be 14 clicks in either direction from the midpoint which means your draw weight can vary by +/-7% of your limb weight. For example, on 30lbs limbs this would equate to about 2lbs up or down. The QuickClick system can be locked in place with the tightening of a grub screw. This predictability means the zero (mid) point can easily be found by turning all the way to one extreme then coming back 14 clicks. The QuickClick system really needs to be licensed and put on every single bow. It's so damn useful!

Looking at the downside of the HFVD system. It is susceptible to the cold. Now admittedly it has to be pretty damn cold to affect the fluid .. -20'C/-4'F. The manufacturers advise not storing or using the bow at these temperatures due to the liquid freezing and rupturing the tubs! However, few archers store their bows in the freezer and even fewer who would want to shoot at those temperatures!
(Yes, the GA archers you are thinking of would shoot in that weather, but they aren't normal!. Actually, just thinking about it, will you need a dipstick to check the oil levels in your bow? If you are at a competition and your bow's check oil light comes on, do you need to call the AA/RAC? ... Or are we overthinking this and need to cut down on the late night caf? ;o)
There's is also a little bit of a "hmmm" regarding the weight of the riser. It’s listed at 966g which is extremely light for a 25" aluminium riser. Not sure that's really enough to absorb a lot of vibration even with the tubs at least according to current recurve and barebow meta. The current trend is pushing aluminium risers up into the 1400g+ range but as usual extra weights/stabilizers can be added for a custom feel and there's nothing wrong with challenging accepted thinking.

So what can we take away from the above. Well, we were bemoaning the fact recently there were no new ideas in recurve archery for stabilisation and vibration suppression. Can't complain about it now as this is quite a radical departure from the recurve norm of "bushings everywhere" or even bare bow's "just add weight". The riser does have the standard top/bottom rod bushings and capacity for a long rod/side rods/V bar. However, the designers obviously have faith in their hydraulic system as there aren't any more (that we can see). For Barebow, it looks like they have lots of new parameters to play with in their set-ups. The suppression system will radically improve their post shot feel. Then the quick tillering process on the QuickClick system means they can run all sorts of weird tillering set-ups for different distances and have them quickly and reliably to hand when required. Fun times indeed for those who shoot bare (oh matron!).

In conclusion this is a pretty radical departure from the norm and usable by both recurve and barebow archers. The QuickClick system alone would make this a riser of note but coupled with the hydraulic tubs makes this an extremely groundbreaking product. The high price we've seen hinted at (actual ££££ as yet unknown) might be a bit of a hard break on large sales volumes but we haven’t actually seen them in the archery shops yet so no hard data to go on. Thinking about it, a high price tag might not be that big a deal for this sort of boutique riser - specialist, unique, groundbreaking. There are always archers willing to spend to get something different. Encouraging that we support innovation but a little sad that we are such slaves to archery marketing!

Final word: Somewhat impatiently, we are looking forward to seeing one on a line somewhere .. should be pretty interesting as this might actually be a potential future for vibration suppression and tillering in bows. As usual, time will tell.

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Smartriser's website can be found here with a very interesting gallery containing pics and some video.

**6000 Series Aluminium - Containing manganese and silicon, allows the alloy to be solution heat-treated which improves the strength of the material