Middleburn RS8 X-Type Cranks - Reviewed

Middleburn RS8 X-Type Cranks

Being from the British Isles you might expect me to rave about how good Middleburn products are, and on one point you'd be right. But it's not because I'm British that I do this, definitely not. Give me something made and designed by a monkey in the swamp of a far flung land and I'll use it and recommend it, but only if it's actually any good. If it's not then it either doesn't get used or we say it isn't any good. In the case of Middleburn I have bought products of theirs in the past with my own money and, in the case of their RS7 cranks, have raced downhill on the same pair since the start of 2006. Five years of solid abuse on the same set of cranks is good in anyone's book. Unfortunately, whilst these cranks are superb, the bottom brackets they use are less so and, in the case of 83mm bottom bracket shells, not the easiest to track down. Two bottom brackets a season has been the average and this is far from ideal when they're not exactly cheap. So it has been with baited breath that we eagerly awaited the release of the new external bottom bracket compatible cranks.




With Middleburn, everything except for the crank arms is open to change and custom spec'ing, so we'd best start with the basics. With everything designed in house, Matt at Middleburn has worked hard to maintain the uniqueness of Middleburn whilst stepping up the game significantly over the previous RS7 & RS8, themselves still very good cranks. Based on a very similar design to that of the lightweight RS8, but with greater strength than the RS7, this has clearly been successful. With an increased Q-factor to clear wider chainstays, the bare 7075-T6 crank blanks are forged in Italy before the final machining work is carried out at Middleburn's headquarters in Hampshire, England. With each manufacturer having its own subtly different take on the whole X-Type setup, Middleburn has come up with a modular design that enables one set of components to work across a number of different fitments with just one key part change. This means that a set of cranks can easily be assembled to suit your specific needs with the minimum of delay simply by pulling together the individual parts required. So how does it all link together? Well, at the heart of it all is the aluminum axle we discuss below.

Featuring a taper spline fit on both sides, the non-drive side is held in place by a bolt and bonded in place using 603 Loc-tite bearing retainer. In short, it isn't going anywhere once it's torqued up and set using the hefty bolt that holds it all together. And that leaves the drive side to also fit onto the same taper, this time using a self extracting bolt to aid removal. In use it all fits together smoothly with just the thinnest smear of anti-seize on the axle to make removal in the future just as pain free as the assembly.




Rather than utilize press fit spiders, the beauty of Middleburn has always been the modular system with which you can tailor the crank arms to suit your specific needs by changing the spider, either at the time of purchase or at a later date should you want to try something different. It also means that if you damage the spider it is a simple and quick job to change by simply unscrewing the lock ring with a Truvativ/XTR BB tool and swapping it out. Far cheaper than having to replace the whole crank assembly as a result of a wayward hit on a rock. With our downhill bike yet to be built up we elected for a Two-by set up for our all-mountain rig to replace an aging pair of M952 XTR cranks that were already being run with a similar arrangement of cogs. Whilst we could have gone for a standard 4 arm arrangement and just missed off the inner ring we instead decided to go the whole hog and fit the fantastic Middleburn Duo arrangement which you see here. Although this is clearly aimed at those willing to climb too, gravity merchants fear not for we will also be arranging for a pair of these to be fitted to our newly arrived Intense M9 as well. The arrival of 83mm compatible axles should coincide perfectly with the new rig too so as soon as that arrives we will be out punishing these cranks to see what they're capable of in downhill terms. Based on our experiences with the older RS7s we have no doubt that they will stand up to all the abuse we can give them and still come back for more.




So the Duo - what exactly is it? Well, simply, it's a two ring setup aimed at all mountain and cross country riders. The inner ring attaches directly to the splined crank arm, acting as the spider for the outer ring which is attached by three bolts. It's neat, feels stiff and seems strong. With standard sizes coming in at 27t/40t and 29t/42t, we elected for a slightly oddball 29t/40t which highlights the flexibility that Middleburn are able to offer with their products. The shifting isn't quite as good as it is on a 26t/39t arrangement (something that Middleburn should soon be offering) but the benefit is that it allows us to even out the chain ring usage and then use a closer ratio 11-28 road cassette at the back.

Middleburn offer a number of different ring types as well, with a couple of finishing options dependent on budget and what you're after. At the top of the tree is the Hardcoat Slickshift which manages to combine smooth shifting with longevity matching that of the very best steel rings. We feel that the ultimate shifting performance is perhaps a couple of fine points down on the very best that Shimano and Race Face have to offer when new, but that it more than makes up for this by working far better when the conditions deteriorate or after the initial newness has worn off the others. In fact, whilst some point out that the Middleburn crank set up is heavier than XTR, it is worth noting that the arms themselves aren't, and that the extra weight comes from those tough, stiff and ultimately long lasting rings. Worth pointing out too that many UK riders replace their stock XTR rings with Middleburns when the time comes, thus negating any weight saving anyway.




So what exactly are Hardcoat and Slickshift? Hardcoat is a Teflon impregnated ceramic coating that is oh so slippery if you're using an oil coated chain and is very resistant to wear. The teeth are also tough, surviving rock strikes well and generally taking abuse in their stride based on our experience when we've run these rings extensively. Slickshift is slightly simpler and refers to the chain rings being ramped and pinned for smooth shifting, obviously de rigour nowadays, but this wasn't always so and the name has stuck. As well as the Duo, there are the normal triple, single speed and downhill spiders available which means you can pick a style specifically for your needs.




Utilising a standard fit external bottom bracket assembly, you have the choice of many because this crank set doesn't actually come with one. We chose to fit it using a cheap and cheerful Shimano Deore item we had in the toolbox, but if you want something a little longer lasting or with a bit more bling then there are plenty of options out there. With these cranks, the usual 2mm axle spacers are eschewed in favour of a threaded collar on the non drive side to both take up the slack and preload the bearings correctly. This is necessary as the drive side crank arm tightens up onto a fixed position on the splined axle and thus takes no part in the preloading, other than to give the collar something to push against. In reality it's very similar to the system used by Shimano on the XTR, but the collar on these Middleburns doesn't need any specific tools to tighten thanks to its design. Instead it can all be done by hand before nipping up the small pinch bolt to keep it all in place.





Some reviews have cited a lack of stiffness in the arrangement, but it is simply not something that came up as an issue for us during testing. Even the RS7 cranks we have fitted to a V10 which has spent plenty of time racing doesn't make us think that the cranks are too flexible - far from it. Whilst it depends on the type of rider you are these things are all subjective and there is a limit at which it ceases to be an issue or even noticeable. Saying that one stiff crank is slightly less stiff than another stiff crank is a moot point; they're both stiff enough to prevent a 'blind tester' actually telling them apart. There is also, in the opinion of this tester, the potential for a part to be too stiff as the force that would otherwise have been absorbed at one point is simply passed along the chain to the next weakest point. As with all things in life the answer is not clear cut black and white, but if you were to ask if there's noticeable flex in the product when you're using it then the answer would be no. Well, not unless you're either Jabba the Hut (in which case we aren't so can't comment) or you start comparing it either to Saint or Diablous, both of which are significantly heavier, significantly stronger than most riders need and have the downside of transmitting a lot more sharp un-damped shocks to the rider. It is also an unfair comparison given that these are trail/AM cranks that just so happen to be perfectly strong enough for more than the average downhillers cranking needs.

So what do we think? Being a fan of the older RS7 cranks, we had high hopes for these and we haven't been disappointed during the time we've so far had them on a bike. The shifting has been smooth and remained consistent regardless of the slop, mud, grit and general nastiness we've ridden them in and, once fitted, we simply haven't had to touch them. Fit and forget in the best possible way. In fact, the only thing we can find an issue with is that, as with all color anodized cranks, the black anodizing on these is wearing through on one crank from heel rub, but given that it was our choice to go with black it's no big deal. Bare silver arms are also available and, as these resist noticeable wear significantly better, would be our choice in the future. We're looking forward to the option of an 83mm axle being available so we can get them fitted on the downhill bike too, but in the mean time we'll keep running them as we are on the trail bike.




It would be nice to see a Middleburn bottom bracket included, but this would significantly push the price up and in this case gives riders the option of the full spectrum of those already on the market, from the basic we have fitted right through to those top of the line ceramic offerings. A lifetime warranty on the arms, a multitude of custom options for rings, sizes and spiders, downhill tough at a cross-country weight, at a price that isn't over the top, these are definitely high on our list of favorite cranks right now. Recommended if you're after something that is tough and durable whilst at the same time a little different to what some of the bigger manufacturers have to offer.



Prices with Harcoat and Slickshift rings as appropriate (not including BB):

• Uno XC £240 - 32/34/36t available.
• Duo XC £279 - as tested, 27/39t and 29/42t combinations are stock.
• Triple XC £317 - available in both 4-arm and 5-arm compact sizes.
• DH Single £213 - no chainring.


Check out the Middleburn website to learn more.

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