{"id":49453,"date":"2023-05-13T13:00:26","date_gmt":"2023-05-13T11:00:26","guid":{"rendered":"https:\/\/www.bikeradar.com\/?p=724389"},"modified":"2023-05-13T13:35:46","modified_gmt":"2023-05-13T11:35:46","slug":"whats-the-best-tyre-size-for-gravel-riding-40mm-and-50mm-tyres-tested-back-to-back","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/whats-the-best-tyre-size-for-gravel-riding-40mm-and-50mm-tyres-tested-back-to-back\/","title":{"rendered":"What\u2019s the best tyre size for gravel riding? 40mm and 50mm tyres tested back-to-back"},"content":{"rendered":"

Tyre width is one of gravel\u2019s hot topics \u2013 but what\u2019s faster, 40mm or 50mm? <\/p>

By Liam Cahill\n \t\t<\/p>

Published: Saturday, 13 May 2023 at 12:00 am<\/p>

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Huge tyre clearances are one of the hot trends for gravel bikes, but the question many riders are asking is, are wider gravel tyres actually faster?<\/p>\n

As the gravel category has grown, so have tyre clearances. Gravel bikes<\/a> cover a broad spectrum but, at the \u2018any terrain goes\u2019 end of that spectrum, clearances upwards of 50mm are now common. We\u2019re heading into mountain bike<\/a> territory here.<\/p>\n

So, what\u2019s the best tyre size for gravel riding<\/a>? Well, the answer\u2019s complicated and depends, as ever, on where and how you ride \u2013 but matching an appropriate tyre size to your riding intentions is one of the most important factors in gravel bike setup<\/a>.<\/p>\n

To shed some light on the issue, I tested 40mm and 50mm tyres back-to-back. First, I rode a test lap to challenge the bike over a mix of terrain, so that I can comment on how the bike rides with the two different tyre sizes.<\/p>\n

Then I headed to a new location to complete a series of timed roll-down tests to find out which tyre size is the fastest.<\/p>\n

Between these two tests, I\u2019ll aim to shed some light on the tyre size conundrum for gravel riding, but first, let\u2019s take a closer look at the test mule.<\/p>\n

The bike<\/h2>\n
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The Lauf Seigla has space for 57mm tyres on 700c rims.<\/span><\/figcaption> Joe Norledge \/ Our Media<\/i><\/span><\/div>\n

To help me carry out this testing, Lauf sent over its Seigla gravel bike<\/a>.<\/p>\n

To test wide tyres, you\u2019ve first got to have space for them in the frame and the Seigla can comfortably accommodate our tested sizes. In fact, the Seigla, launched last year<\/a>, has space for 57mm (or 2.52in) tyres on 700c rims<\/a>.<\/p>\n

Given that I would have to get myself back up to the top of our roll-down test hill, the lightweight carbon frame would come in handy, as would the 10-44t cassette<\/a> on the SRAM Red XPLR groupset<\/a>.<\/p>\n

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Lauf sent us two sets of wheels for the test.<\/span><\/figcaption> Felix Smith \/ Our Media<\/i><\/span><\/div>\n

Lauf supplied the bike with two sets of wheels and tyres, enabling me to quickly swap over to what was needed for all 24 runs of the roll-down test.<\/p>\n

The wheels themselves were e*thirteen\u2019s XCX Race<\/a> carbon gravel wheels. With an internal rim width<\/a> of 24mm, they\u2019re an ideal match for the latest gravel bike tyres<\/a>.<\/p>\n

In terms of the rubber, I opted for a set of Maxxis Rambler tyres<\/a>, chosen because they\u2019re a relatively common choice for all-round gravel riding<\/a>. They have a tight tread pattern, well-suited to the roll-down test, while the 120 TPI, tubeless-ready bead makes for a supple combination capable of handling the low testing pressures. Crucially, they\u2019re available in 40mm and 50mm sizes.<\/p>\n

The test protocol<\/h2>\n
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Tyre width was the only change between laps.<\/span><\/figcaption> Felix Smith \/ Our Media<\/i><\/span><\/div>\n

The lap test took in a variety of off-road terrain, including loose corners, a steep pitch and muddy ruts. Here, just one variable \u2013 tyre width (40mm and 50mm) \u2013 changed between the two laps.<\/p>\n

For this test, I optimised the tyre pressure for each width using Silca\u2019s pro tyre pressure calculator<\/a>, which takes into account system weight, gravel surface and a range of other influencing factors.<\/p>\n

For the roll-down test, two variables were tested: tyre width (40mm and 50mm) and tyre pressure (25psi and 35psi). I also tested each combination on two lines for the roll-down test: a smooth line and a rougher line.<\/p>\n

The aim here was to establish the fastest combination for gravel riding. It\u2019s worth noting, however, that, while rolling resistance is often the main focus, the weight, aerodynamic profile and casing tension of the two tyres would have an impact on performance, too.<\/p>\n

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For the roll-down test, I changed the tyre width and pressures.<\/span><\/figcaption> Joe Norledge \/ Our Media<\/i><\/span><\/div>\n

I rode each line three times \u2013 making for 24 runs in total \u2013 to provide an average time for each setup.<\/p>\n

Now, this is a real-world test, not a lab test, but for both the lap test and roll-down test, as many variables as possible were kept the same. This is key to being able to spot differences in whatever it is you\u2019re testing, enabling you to be sure your results haven\u2019t been influenced by external factors.<\/p>\n

Given the nature of testing in the real world, especially during spring in the UK, finding a weather window to allow for consistent conditions was tricky.<\/p>\n

The pictures you see of the roll-down testing were shot on our designated filming day. The actual testing took place on a far calmer and sunnier day, as you can see from the GoPro footage in our video. It was important to record the data on the calmest day possible to keep it as consistent as we could.<\/p>\n

Lap test<\/h2>\n
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The lap test was designed to push Liam and the tyres.<\/span><\/figcaption> Joe Norledge \/ Our Media<\/i><\/span><\/div>\n

I kicked things off by riding a back-to-back lap test, on a trail designed to push the tyres, and myself, fairly hard so I could get a feel for their limitations.<\/p>\n

For the 40mm tyres, the rear tyre was set to 42psi, while the front was set to 40psi. For the 50mm tyres, my rear was set to 28.5psi, while the front was run at 27.5psi. The sealant level was kept the same.<\/p>\n

I focused this part of the test on ride impressions, and how the tyres felt over a variety of terrain, rather than lap times.<\/p>\n

The course was designed to be around five minutes long, with as many surface changes as possible, including the natural features, such as roots and rocks, that many riders will find on an off-road \u2018gravel\u2019 ride.<\/p>\n

Conditions were perfectly calm and the course was a mix of dry and wet. These conditions remained constant throughout the lap test.<\/p>\n

Lap test ride impressions<\/h2>\n
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The 40mm tyres \u2018felt\u2019 more sprightly.<\/span><\/figcaption> Felix Smith \/ Our Media<\/i><\/span><\/div>\n

The first thing I noticed was that the narrower 40mm tyre felt (and I should emphasise \u2018felt\u2019) faster on most sections of the course. Off the start line, the bike felt far more sprightly and, on the straight drags that made up the first half of the course, speed felt easier to maintain.<\/p>\n

Flying into the wooded sections, I didn\u2019t feel as though the narrower tyre lost much to the 50mm tyre in terms of cornering composure or grip, and on muddy sections I actually found the 40mm tyre to be a bit better.<\/p>\n

It seemed to bite down into the mud a little more, finding better traction, whereas the wider tyre floated a little, making it harder to track through ruts.<\/p>\n

Through the corners, however, I was far more confident on the wider tyre. It seemed to run wide a few times, but this may be because I felt I was able to leave the brakes alone. Even if I hit debris on the exit of a corner, the wider tyre remained planted.<\/p>\n

In contrast, the narrower tyre suffered from a little loss of traction as I winched my way up the steep kicker. Generally, it felt easier to climb off-road technical stuff on the wider tyre because it felt noticeably grippier.<\/p>\n

Roots, rocks and any impacts were also a lot smoother to ride on the wider tyres \u2013 something that didn\u2019t surprise me at all.<\/p>\n

Roll-down test<\/h2>\n
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The roll-down test was conducted on a 770-metre-long straight, losing 50 metres of elevation.<\/span><\/figcaption> Felix Smith \/ Our Media<\/i><\/span><\/div>\n

But what about pure straight-line speed?<\/p>\n

Rolling resistance, aerodynamics and weight are the three main forces acting against you during a gravel ride, and the traditional thinking is that wider tyres are slower, because they\u2019re heavier and less aero.<\/p>\n

Our test segment was 770 metres long, losing 50 metres of elevation in that time. The left-hand side was heavily rutted, with large stones and some significant impacts. This acted as my rough line.<\/p>\n

The right-hand side was our smooth line. For the most part, this was finely graded gravel with only a few patches of small, loose stones.<\/p>\n

I started each run rolling at 20kph. At the start line, I began a lap on my Garmin Edge 1040<\/a>. I didn\u2019t pedal after the start line, kept as close as I could to the same body position for each run, and also tried to keep my line choice as consistent as possible.<\/p>\n

Conditions on the day of testing were as good as could be expected for the time of year. I was treated to full sunshine, light winds and beautifully dusty gravel.<\/p>\n

Roll-down test results<\/h2>\n

Smooth gravel<\/h3>\n
<\/colgroup>
Tyre width<\/th>Pressure<\/th>Time 1<\/th>Time 2<\/th>Time 3<\/th>Average time<\/th><\/tr><\/thead>
40mm<\/b><\/td>25psi<\/td>01:02<\/td>01:04<\/td>01:03<\/td>01:03<\/td> <\/tr>
40mm<\/b><\/td>35psi<\/td>01:06<\/td>01:08<\/td>01:06<\/td>01:06<\/td> <\/tr>
50mm<\/b><\/td>25psi<\/td>01:05<\/td>01:03<\/td>01:06<\/td>01:04<\/td> <\/tr>
50mm<\/b><\/td>35psi<\/td>01:04<\/td>01:05<\/td>01:07<\/td>01:05<\/td> <\/tr><\/tbody><\/table>