Venn 259 THL gravel Disc

Description

The Venn 259 is probably the rim you actually want for your gravel bike – but it just isn’t the one that you think you want.  Why is that?

1. It is hookless – which is naturally lighter by design.  So a hookless rim is stronger for a given weight.
2. It is shallow.  Shallow rims are also…lighter by design – so they are also stronger for a given weight.
3. Being shallow it is also naturally more compliant by design.  Flat rims do comply better AND they require longer spoke lengths and those spokes comply more.
4. The design of the 259 is specifically intended to deliver maximum compliance.  When I first rode this rim, I thought I had a puncture.  However despite the incredible compliance, it is laterally very stiff owing to its width and again the nature of the layup.
5. It is internally wide but not excessively wide.  There is a growing trend for gravel rims to be 30mm internal and more.  These come with problems – they make the sidewall of the tyres much more vulnerable and they start to reduce the height of the tyre making impacts more problematic – you are more likely to bottom out.  Narrower rims help with this but when you go too narrow the tyre becomes less stable and the air volume inside the tyre is reduced which reduces comfort.  23-27mm internal is around the optimal dimension for gravel depending on your tyres of choice – don’t take my word for it – this is also the guidance from the ETRTO and in line with what most tyre manufacturers recommend.
6. It isn’t aero…..I know you think that an aero gravel rim sounds like a great idea.  On a gravel bike you can get aero gains – you could wear aero oversocks or an aero helmet or a skinsuit, you could have an aero bar and you could change your position getting lower for example.  You probably don’t want an aero frame as these tend to be heavier, less stiff and less compliant (not great for a gravel bike) and you don’t want aero rims because:
   1. • They won’t be.  The gains, if they exist, are tiny – because you have to think of them as a system and its virtually impossible to make an aero system with a gravel tyre which is big with lumps on it. The best thing you can do to have aero gravel wheels is run a 35c tyre or less and let it be a slick one….i.e. – put a road tyre on.
      • Aero rims would undermine the benefits outlined above – compliance, adding weight but in addition – while they may not be aerodynamically lower drag – they definitely can be aerodynamically unstable – i.e. caught in cross winds making your handling much more challenging.  These things are easier to handle on a gravel bike but an aero gravel wheelset isn’t what you want at the top of an exposed windy bridleway on a ridge.

The Venn 360 is a good alternative compromise if you wanted a rim which is a little deeper.  It is still compliance focused, it’s still light – it is hooked which allows the use of any tyre you wish (hookless rims cannot be used with all tyres) – it is 23mm internal – it will give you an aero benefit with the right sort of tyre pairing – e.g. a 30c road tyre and it is shallow enough not to be unstable.

Some people do like deeper rims for muddy riding.  If mud closes over the top of the rim it weighs down more than if it isn’t able to.