Piggyback v Non Piggback Shocks

Longer travel bikes have become the norm these days, rewind to 2004 and my 170mm bike (weighing in at over 40lbs) was a monster. Despite costing around £3,000  (a fair amount at the time) it was pretty terrible and not much fun anywhere without an uplift, “big fat wallowy mess” is how I remember it.

Anyone who has been riding for a decade or more has probably noticed how much more flexible bikes have become. This has in part led to the popularity of Enduro racing, bikes that soak up the big bumps with ease can now be pedalled back up a hill too. Most frames of 140mm and above have sufficient clearance for a piggyback, the bigger question is whether you need one?  So apart from appearance what are the main differences and why make them in the first place?

Piggyback v non piggyback shocks, mtb suspension servicing, lancashire, mtb shock service

A great piggyback shock – Fox Float X CTD

Piggyback V Non Piggyback shocks – Advantages

Why have a piggback at all? The important thing to remember is that just because a shock has a piggyback doesn’t necessarily mean it has more features than a non-piggyback shock. A non piggyback shock can still have the same range of compression and rebound daming adjustment. Primarily the aim of the piggyback design is to increase performance, the thinking is thus:

  1. By keeping the IFP and damper charge (usually nitrogen) away from the main body of the shock, heat build up over a long descent isn’t as much of an issue. The build up of heat can dramtically change damping characteristics and can cause the charge in the IFP chamber will expand. Pressure will increase as a result and effectively speed up the rate at which the damper will try to return. Nitrogen has a lower expansion rate which is why it is used in rear shocks. At the same time the heat build up means that the damper fluid is becoming less viscous (thinner) and is less able to slow down the shock. From the rider’s perspective the shock will become faster, both in compression and rebound, this is called “shock fade”. The fact that the IFP is seperate from the shock body means that area will be cooler. In addition because of the greater oil volume in the piggyback shock more heat energy can be absorbed for relatively smaller amount of viscosity reduction. Basically more oil means it stays thicker and more capable of doing it’s job for longer.
  2. Splitting the load of a shock between two compression circuits can make a shock feel less harsh especially under fast compression and generally more active at the start of the stroke. In our experience this can be quite pronounced. For example the Rockshox Monarch Plus and Fox Float X CTD usually appear smoother at the start of the stroke than the non-piggyback Rockshox Monarch RT3 or the Fox CTD.
  3. Many piggyback shocks have a larger IFP volume that their non-piggyback counterparts. This greater volume translates into a more linear stroke and the amount that the shock “ramps up” towards the end of it’s stroke may be less in a piggyback shock. It’s the same priciple as volume spacers in your air can, the more space there is, the more “linear” your shock will feel. This in itself isn’t necessarily a disadvantage, you may prefer the shock to ramp up more, but starting out with a shock that is more linear gives you the opportunity to adjust the shock to your preference.

    Piggyback v non piggyback shocks, mtb suspension service, preston, lancashire

    A very technical drawing – the layout of a Piggyback and a Non Piggyback Shock

Piggyback V Non Piggyback shocks – Disadvantages

The advantages that piggyback shocks can afford us aren’t relevant to everyone. Whether you will benefit from a piggyback shock depends upon where and how hard you ride.  Disadvantages will also include:

  1. Piggyback shocks cost more to buy in the first place, for example the current RRP on a Monarch Plus RC3 is currently £469 versus £366 for for the RT3.
  2. Piggyback shocks cost more to service, service kits cost quite a bit more and the labour charges for servicing will be higher.
  3. Some people may not like the more active feel of a shock that is more active or linear. For example you might have one bike that you use for everything, if you are a cross country mile muncher who loves to beast the climbs and you may find a piggyback shock a bit “wallowy” for your liking.
Fox Shock service, Fox CTD service, RP23 service, Float X service

A non Piggyback Fox Float RP23, quite a bit more technology going on than some realise.

If you ride natural trails in the U.K. for example, dipping into trail centres and maybe one or two Enduros per year then spending the extra money and taking the maybe 120g weight penalty (Monarch Plus RC3 335g v Monarch RT3 215g) won’t necessarily mean that you will enjoy your bike more with a piggyback shock. You may not have the luxury of a descent long enough or be comfortable to ride hard enough to have experienced shock fade, but those who have will probably want to do all that they can not to repeat the experience. Then again maybe you haven’t experienced shock fade but just like the magic carpet feeling that a well set up piggyback shock can give you.

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I wouldn’t necessarily go charging out to buy a new piggback shock unless you know why you want it. If you run a basic shock with only rebound adjustment then something like a Fox DPS or a Monarch RT3 will be Worlds apart without delving into piggyback money/servicing costs. If you get the chance, riding a friend’s bike or a demo bike may help you decide. If you haven’t had your shock serviced in a long time a much cheaper option that may yeild dramatic results is to just have your current shock serviced, you may be surprised. We supply shocks and service them so we are completely unbiased, up to you guys and girls. 🙂