The Tubolight Diamana tyre insert has a unique shape that is different from other inserts on the market. The SL version is the lightest in the range (it's competitive in weight with other options) although that is not the primary goal. Tubolight uses terms such as airflow, venturi and ground effect, and dimples to describe its Diamana tyre inserts. We tested them to find out if the benefits could be noticed.
- Vittoria Air-Liner Light tyre insert review
- Cushcore Trail tyre inserts review
- Tubolight EVO HD tyre insert review
Tubolight Diamana SL tyre inserts – Technical details
Tubolight makes three variants of the Diamana, each aimed at certain riding categories. The SL (pictured here) has the shortest profile and lowest claimed weight at 97g each. The HD has a higher density and deeper profile at 145g, while the XHD goes up to 220g.
The company established itself by developing the lightest tyre inserts available with the now-discontinued original EVO SL weighing only 60 grams per insert. Although they are no longer the lightest available, the Tubolight Diamana are still lighter than the majority of other alternatives. Cushcore inserts for mountain bikes start at around 160g, whereas Rimpact's original V2 starts at 110g.
Where things begin to differ from other options on the market is Tubolight's claims about the shape and benefits it provides within the tyre carcass.
Tubolight has examined how the tyre compresses and rebounds when riding, resulting in inconsistent tyre pressures and reduced traction. The claims of a 9% reduction in rolling resistance, a 55% improvement in vibration damping and a 60% increase in tyre pressure on the ground are all bold.
Aside from the claims, the tyre has a broad profile that extends the insert beyond the rim's edge. Brands such as CushCore have inserts that provide wide coverage but not quite to the same extent. However, the area covered is quite slim and, with a lightweight foam composition, the SL version is unlikely to be the best choice if rim protection is your primary concern; the HD and XHD may be better options.
Tubolight Diamana SL tyre inserts – Installation
Tyre inserts can be difficult to install, with factors such as the insert itself, tyre type, wheel size and width all affecting the process. The Tubolight EVO gravel insert was straightforward but the Diamana's structure is different, with a closed-cell EVA foam and less stretch than the EVO inserts it wasn’t quite as simple.
The wider shape and profile, as well as having less stretch, make these a little more difficult to install than the EVO versions – but they did not leave me shouting and swearing as some others have. I found a different method for fitting them that worked well because of the shape of the insert. I positioned the insert so that one raised area was inside the rim and installed the final at the same time as the tyre, rather than simply having the full insert in place before the final tyre bead.
A potential cost saving comes from not requiring a specific type of valve that some other tyre inserts require, which allows air to flow laterally instead of vertically. This is because the insert does not sit flush against the valve top and should always allow air to pass through.
Tubolight Diamana SL tyre inserts – Performance
The foam material is firmer and denser than the EVO versions but with a lower height within the tyre. Pinching the sidewall (a very unscientific test, yes) resulted in what felt more supple than a tyre with the Vittoria Air-Liner Light fitted. The lower profile and form are most likely the main reasons, while other inserts take up more volume and have a more circular shape within the carcass.
While riding, I was happy to continue to ride with the low pressures that I had been testing with the Vittoria Air-Liner Light and went as low as 18psi (1.24 bar) on the front tyre. I was still able to ride at the same speeds on the downhills without stressing about rim hits.
Despite riding at lower pressures and on rocky terrain, I didn't have any harsh rim hits but this is always a tricky and subjective area to test. To directly compare to the Vittoria Air-Liner Light, I deflated both wheels and rode side by side to check how they differed in terms of support and feel. The Diamana inserts feel closer to the rim and, when completely flat, you notice more impact but they also provide a more connected and secure ride. Both inserts kept the tyres in place without losing any sealant and I was able to ride on both when flat – they ride differently, however, and provide different levels of protection. The Air-Liner Light is more cushioned but it drifts when turning, while the Diamana SL has better steering but less cushioning. After this short deflated test there was some damage noticed – you could expect more damage if you needed to ride for an extended time when deflated or when off-road.
There are, of course, debates about enhanced airflow, the venturi effect and the possible benefits they offer. There is no process to quantify these claims and Tubolight provides no information on how they were tested either. We cannot dismiss the claims and no performance benefits can be attributed solely to these areas. In terms of performance alone, the Diamana SL works well and, for cross-country use, they provide a very good balance of rim protection and tyre support. Then there's the benefit of being able to nurse the bike home or to the pits with a deflated tyre.
Tubolight Diamana SL tyre inserts – Verdict
Diamana inserts cost £99 for a pair and are not sold individually. You can get them in pairs or mixed sets, SL/HD and HD/XHD, which may be suited for some riders.
The price for a pair is the same as the Vittoria Air Liner light, which is probably the main competitor. Other options include the Cushcore trail inserts priced at £170 per pair which include valves. Rimpact inserts start from £60 for the Gravel/XC, while the Rimpact Pro/Original mix that Liam tested is now £75.
With the Vittoria Air-Liner Light as the main alternative for XC riders and racers, which is best? After riding both, I believe it depends on what your top priority is when choosing an insert. The Vittoria is lighter and larger, and I believe it will provide better rim protection. Both allowed me to use the tyres at lower pressures while still providing some sidewall support, but the Diamana SL delivers a more stable ride when deflated, which could be useful for races whose primary goal is to get the bike back to the pit area for a change as quickly as possible.
Does the extra volume of an insert have a negative effect? Surely it must, otherwise we would be using something other than air.
Tubolight isn't holding back on making bold claims about the Diamana tyre inserts and I'm sure many will be suspicious of any benefits the dimples and shape will have on airflow inside the tyre carcass. Aside from the claims, the insert has been proven to be a very good, and trustworthy tyre insert.
Some inserts provide better protection and if that is your primary concern, the Diamana HD or XHD versions may be better but, for riders who want a low-weight insert that can still provide some rim protection while allowing the wheel to be ridden flat, the Tubolight Diamana is one of the best mountain bike tyre inserts and priced competitively against other brands.
