e*thirteen has something special inside the rear hub on these Sidekick wheels. Seven years in the making, the brand’s innovative new design claims to end pedal kickback on a full suspension bike and deliver a chainless feel to your ride. Quite a boast then.

It’s done this by building in a deliberate float or deadband to the drivetrain, soaking up the chain growth that pretty much all full-suspension bikes experience. It means as your bike moves through its travel and the suspension starts to tug on the chain and move it backwards, the cranks can still remain motionless and without passing on that kickback to your pedals and feet.

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e*thirteen’s Sylvan Sidekick wheels are my favourite wheel package of 2024, giving a true chainless feel to your bike

Inevitably then, building in this extra float can’t help but build in more lag time when you’re pressing on the cranks to engage the chain and drive the bike forward. Think of it as the exact opposite of a fast-engaging hub then, something we’ve got pretty used to on the best mountain bike wheels of the past few years. And because Sidekick also interacts with the gearing system it’s going to bake in extra lag or hesitation before you engage a gear, more so than rival products doing the same thing, like O-Chain and Rimpact’s Chain Damper, which work on the crankset end of the drivetrain.

Interestingly it’s not the only brand working on the problem though, earlier this year we uncoverd Fox’s plans for a decoupling freehub. Check out the explainer video for that below…

What is pedal kickback?

In order to better understand this review and Sidekick, here’s a quick run down pedal kickback. As a full suspension bike moves through its travel the rear axle wants to move further away from the front chainring, which puts the chain under more tension and effectively pulls the cranks backwards. More than that though, the lengthening chain can exert torque on the rear wheel and turn it forwards.

Kickback can happen when you’re motoring along, but also at slow speeds too where you’re less likely to notice it as your body weight tends to resist the movement. It’s generally considered a bad thing on a mountain bike because it’s fatiguing and reduces the efficiency of the suspension to absorb bumps.

On the brakes and through rough sections of trail is where pedal kickback is most obviously felt on almost any bike

Details and specification

e*thirteen’s design is available as a hub only, wheel only or built up into different complete packages like this enduro and trail-targeting Sylvan with compliant asymmetric carbon rims.

Much like a regular freehub design, Sidekick uses a ratchet ring with teeth that would translate to pawls engaging in 8-degree intervals if the brand hadn’t added another element to enable its unique design to do what it does.

Like any hub, Sidekick disengages when coasting. The difference is there’s a floating ‘pusher’ to control when the pawls reengage with the ratechet, which can be user-set without tools to offer 12°, 15° or 18° of float.

And, because the pawls retract while the ‘pusher’ part is floating, it also means the e*thirteen hub is near silent when freewheeling and offers much less drag than a normal hub where the pawls are continually ticking through the ratchet. I’ve not timed it, but my World Cup mechanic pal tells me this aspect is significant in terms of trail rolling speed.

The Sidekick hub with the usual ratchet pawls and a silver ‘pusher’ to engage or disengage to create that deadspace or float

Setting the amount of deadband is simple. Unscrew the opposite end cap on the steel axle, pull the cassette and freehub body out and set the degrees of float by hand on the red anodized pusher piece. Incidentally, this part doesn’t carry any extra drivetrain loads, it just engages the three traditional pawls on the freehub.

Unlike chainring spider-based solutions where the float is fixed wherever you set it, Sidekick is more complicated and is hugely affected by the gear ratio you’re in. Let’s say you have a regular 32T chainring and you’re in the 16T cog on the cassette, giving a ratio of 2:1. That means with Sidekick set to 18° of float you’ll actually only get 9° of movement at the crank.

Hopefully you’re still following, because the other part of this relationship is that in the 52T cog there is a much broader ‘angle’ of ‘deadband’ compared to the 10T cog because the gear ratio has changed.

It’s a complex concept and the Sidekick effect will be different in every gear. And unfortunately for e*thirteen, the physics works the opposite way to ideal for an MTB, as you’d likely want less lag when you’re higher up the cassette and climbing, and more lag when descending at faster speeds and in a harder gear lower down the cassette.

All this said, e*thirteen’s design still has the potential to offer much more of a chainless feeling than any other product on the market. I’d also agree with the brand’s claims that it also has extra benefits in the ability to fully disconnect the drivetrain from the suspension temporarily.

To go deeper still, e*thirteen’s puller takes a certain amount of rotation to engage the pawls. Couple that with the normal hub engagement lag inherent in all ratchet systems these float numbers aren’t totally fixed.

What that all means is Sidekick can have between 12° and 26° of float just in the hub with a 1:1 gear ratio, in other words when you’re in fourth gear in a SRAM T-type cassette, with a 32T chainring up front. Right, before I lose you, let’s call time on the theory and get to something concrete.

The Sidekick rear hub is bulbous to accommodate the extra moving parts inside

Sidekick construction and spec

Sidekick hubs themselves are made from machined aluminium and use J-bend spokes only with either 28 or 32 spoke drillings. Axle widths are either Boost 148mm or SuperBoost/DH 157mm. The technology inside makes the inner side and central portion much bulkier and the Sidekick design also adds weight. The 148mmx12mm Boost hub with an XD driver body is 450g, compared to around 275g for a DT Swiss 350 hub.

Even with a heavier rear hub, E*13’s Sylvan wheels aren’t exactly heavy as a complete package though. The carbon wheelset I tested (that’s rated for enduro use and light e-bike use) is 1,895g a pair with carbon rims and the brand’s quick fill Presta tubeless valves. That means it isn’t much heavier than many equivalents, plus when it comes to wheels, a heavier hub at the centre will always be less impacting on acceleration and perceived weight than a heavier rim.

The Sidekick hub adds weight and lag to any bike, but I think the payoff is worth it for a super smooth ride

Performance

After all that theory, how does the design actually feel on your bike? Before I delve into the performance (spoiler alert – Sidekick is immediately noticeable and effective) what bike you use E*13’s hub on will obviously affect how noticeable it is. Bikes with higher amounts of chain growth will gain the most benefits, and riders coming from a faster-engaging rear hub will also notice the most difference. These kinds of bikes are most likely to exhibit the negative effect of pedal kickback as a tugging on the chain or the rear wheel driving forwards in g-outs or deep berms.

I’d think about riding your bike without a chain and seeing if you like the feeling first, as Sidekick isn’t a cheap product to get wrong. But it doesn’t take a genius though to see there’s clearly something in it for pure downhill performance when the vast majority of elite DH racers are now using something similar for a calmer and potentially faster ride.

I set the Sidekick hub to the biggest amount of deadband as I wanted to feel the biggest difference, and e*thirteen’s design is noticeable straight away. I don’t just mean in the hesitation before the cranks drive you forward either, I’m also talking about the influence when freewheeling and riding over bumps, where most experienced riders will also notice a difference.

Whether this difference you feel mainly in your feet and suspension is night and day will depend on how tuned in you are to your machine and how much chain growth your bike has, but you’ll definitely notice (and hear) an effect.

From the first lap, the Sidekick hub significantly changed my Santa Cruz Tallboy’s ride feel, it clearly delivers that chainless feeling. It also makes the bike roll noticeably faster, my favourite test track was smoother and quieter down the first fast straight, one that’s absolutely laced with roots and square edge hits.

With Sidekick, the Tallboy shrugged off one particularly big root on my test track that’s always impossible to go light over. No tyre bottoming out, no violent clanging of the rear tyre hanging up and no jabbing at the feet.

The rear wheel just seemed to ride straight through it and over it, which was a shock having ridden this section on most test bikes I’ve had in recent years. None have absorbed this particular section so smoothly and quietly, regardless of how much travel they have or whether they are light and human powered or heavy and electric-assisted.

Short and sweet, Hope’s 155mm Evo cranks are also mechanically effective at reducing pedal kickback

This felt like a big deal, so I went back up to repeat and felt exactly the same thing. I also soon started to decipher that the suspension is so much freer, it feels like you need to add a bit of air to the spring or damping to retain the ride feel you are used to.

Because Sidekick makes the bike flow much more smoothly you aslo have to adjust how you ride. There’s less resistance to the suspension movement and that means there’s less work for you to do to control the bike in terms of pumping and pushing it into the ground. It’s the same kind of feeling I felt testing Hope’s 155mm Evo crankset, but of course it was much more pronounced here.

Sidekick takes some some getting used to because you get used to the chain force or support you’ve got across the drivetrain on any given bike when you come to pump and gain speed out of compressions and little hollows. And honestly, I simply don’t know whether this chain force is making the suspension feel tighter or torquing the rear hub forwards under your weight at the crank to gain drive from terrain or what percentage it is a combination of both. Someone else will have to work out a way to measure all that with telemetry I guess.

What I do know is Sidekick means you adopt a slightly different riding style, kind of just standing on the bike and floating along with the suspension feeling like it will absorb everything more readily. On the Tallboy, it’s not as dynamic a ride though, so it can make a short travel bike feel less urgent and pumpy, which is maybe why you liked it in the first place. But it’s definitely more comfortable, quieter and calmer and feels like you get free ‘extra’ travel.

My test mule is the Santa Cruz Tallboy, precisely because it’s a short-travel and ideal for highlighting pedal kickback… or the lack of it

The Sylvan wheel package

Before I get too lost in the nuances of the decoupling part of this review, let’s talk a bit about the wheel package. I didn’t hear a sound or have a single issue over dozens of rides with the actual Sidekick engagement (once it engages), and the Sylvan wheels themselves have a nicely damped feel and are plenty zippy and easy to chuck about from side-to-side.

The wheelset also feels pretty light and very fast rolling, especially with the way the pawls disengage when coasting. I swapped the Sylvans between lighter Reserve SL carbon wheels that I rate as some of the fastest trail wheels around, and e*thirteen’s set up didn’t feel wildly different in terms of speed when pedalling. That’s high praise given how much I like the SLs and with the same tyre set up at the same pressure there are sections of flat, slightly downhill, bumpy trail where I reckon the Sylvan rolls even faster.

more grip and control and left me feeling really planted and stable on the short travel Tallboy

Another benefit from Sidekick can be felt on steeper and slower tracks, where e*thirteen’s design delivers much more active suspension under braking. It’s very noticeable and translates to having quite a bit more control and grip while on the brakes, with the rear tyre skipping much less over small holes and steps.

The biggest advantage is extra control on the kind of steep, rutted tracks where you’re continually controlling your braking and preventing your wheel from lockingand sliding. The set-up just seems to give more grip and control and left me feeling really planted and stable on the short travel Tallboy.

Everything I’ve described so far is largely welcome, but it’s not all rosy with the Sidekick as there’s a very annoying drivetrain lag (especially higher up the cassette) and an aspect of added noise and extra flailing in the chain. The bike is always much quieter and calmer with your wheels on the ground where it feels like the cranks are hovering and feet are floating. But when you touch back down from being in the air, you occasionally get a violent clang. I assume this is caused by a whip backwards in the chain into the deadband (where traditional pawls would engage), causing extra turbulence, disturbing the mech and whipping the chain into the stays. It certainly makes the bike even noisier than it normally is.

Noise is annoying, but the pause in engagement starting pedalling will be the biggest dealbreaker for many. If you mostly pedal continuously up fireroads or tarmac you might be OK with it as you only feel this when you try to engage the freehub. Plus, the engagement here is very solid (metal on metal), unlike the somewhat spongy feel of O-Chain engaging on the elastomer part of the design.

Where the lag is worse is when you go to engage the cranks on the sort of undulating ground likely in the upper part of the cassette. Here it’s quite a revolution before picking up onto the pawls again and the hub engaging. It’s a sensation not unlike having a really, really cheap free hub on a supermarket bike, but even worse, and it can upset your balance climbing so you might also bang your knee into the stem or even wobble off balance.

Riders who love technical climbing will particularly hate it. Approach an obstacle or wriggle point, you can’t just click your cranks back an eighth of a turn to adjust their position. Instead there’s still nothing there, so you almost jerk forward into freefall, which is a bit of a weird feeling like you could shin yourself on the pedals. This part of the performance means this is essentially a product that is all about downhill performance and to be fair, e*thirteen is pretty open about this aspect.