|I can see the sea from here!|
The only 29+ tyres available as I type are Surly Knards. There’s 2 flavours available, 27tpi and 120tpi, they both share the same tread pattern and look exactly the same. The difference is in the carcass, the higher thread count of the 120 results in a more flexible (maybe even supple) tyre which is both lighter and more expensive than its sibling but possibly a touch more fragile too … you pays your money, etc, etc. Whichever you choose you can’t deny that they’re a pretty hefty tyre, the 27tpi weighs 1270g and the 120 is a comparatively feathery 970g. When you’ve spent years trying to shave weight from your wheels and tyres and are happily charging across the countryside with 500g tyres spinning at each end, the thought of adding a second 500g to each wheel seems crazy BUT in reality a 1kg tyre doesn’t turn your world upside down as much as you’d imagine. The reasons could be really complicated or as I suspect very straightforward.
I think a lot of the potential nasties are cancelled out by the rim. The Northpaw rims fitted to this bike are 47mm wide (lots of aluminium = heavy) but have very, very
large cut-outs (big holes = light) which means they tip scales at 600g each. While that’s not an xc race rim, it’s not that heavy either. I believe the second reason for the surprising lack of drag is the shape of the tyre when it’s fitted. The 47mm rim produces a nice rounded profile, so the tyres contact patch isn’t as big as it’s 3″ size would have you believe (obviously tyre pressure plays a part here). If you then take the tyres tightly spaced, shallow tread pattern in account, the lack of rolling resistance you might have expected comes as less of a surprise. I’m not going to tell you that you don’t notice the tyres when gravity isn’t on your side, you do but it’s not as much as you’d expect. As a comparison, the difference between riding an unloaded bike and one packed with a summer nights worth of gear is far more noticeable.
|Ti bike = Fanny magnet|
Before I carry on rambling there’s one thing you need to understand … A 29+ isn’t a fat bike! The 3″ tyres don’t provide the same levels of flotation as a fat bike tyre and they won’t offer the same ‘suspension’ (cushioning) effect either. I feel that the last point is actually a positive trait rather than a drawback. Any ‘suspension’ provided by a tyre is completely undamped and you wouldn’t dream of fitting an undamped fork to your bike – even if someone paid you. The ‘suspension’ action of the Knard is just on the right side of too much and while you can feel a tiny amount of uncontrolled rebound on fast rocky descents, it never gets out of hand or makes you think slowing down might be a good idea. The 29+ effect really comes into its own on rocky tracks when gravity is on your side. I’m not talking fields of football sized boulders, more rocky bridleways and tracks where the bike really does seem to float over the top of everything beneath it.
So what about grip? … Grip’s something that’s difficult to quantify in any meaningful way. Technique and individual riding style will play a major part in how much grip’s available, so all I can do is compare it to a ‘normal’ 29er ridden in the same conditions. Descending was never an issue, even when negotiating slippery off camber sections, I never experienced any ‘iffy’ moments but I very rarely do on 2.2″ tyres either, so I honestly can’t say whether the 29+ is better or not (sorry). Climbing on the other hand is something I can comment on with a little more insight. I’ve always found that 29″ wheeled bikes have the potential to grip better than 26″ wheeled bikes … and the 29+ has the potential to grip better than a 29er. The large contact patch of the tyre obviously helps but the bigger circumference does too. There’s much less traction breaking ‘snatch’ when climbing, your jerky, breathless on-off, on-off pedal action doesn’t get translated into on-off, on-off wheel rotation, so there’s less chance of the tyre breaking free. It’s worth bearing in mind that the Knard isn’t the most aggressive tyre in the world, so the bikes climbing ability certainly isn’t enhanced by it … it’ll be interesting to see what effect one of Surly’s soon to be launched ‘Dirt Wizard’ tyres would have.
The Travers bit.
|Full fat and the low fat alternative.|
|If you widen the drop-outs a touch?|
The Rudy Fat 29+ is available as a frame only or as a rolling chassis kit. Prices start from £1199. The Travers ‘Prong’ carbon fork is also available separately from £249 in both 26″ and 29″ versions.