The gravel trails we ride can include lots of climbs, that range from gentle valley routes on shallow gradients to more challenging climbs on steep gradients. The gravel can be hard-packed or loose. It can be finely groomed or it can be more rocky. We also have strada bianchi style chalk road, farm tracks, double track, single track and unspecified concrete tracks. On many of our off road routes, there’s also little to no requirement to ride on any of the perfect tarmac roads for which the region is famed, and it’s easily possible to spend the whole day off road gravelling In the mountains, the Tuscany of Valencia hills and farmland.
Our gravel bikes
We are lucky to have a range of gravel bikes for personal use as well as bikes in our hire fleet. Our GT Grade’s sport an 11 speed GRX 1x Group set, aluminium frames and carbon forks, running on Vittoria Mezcal 38c or 44c tyres. The head tube angle varies between frame sizes and ranges from 69.5 and 71 degrees. They have long 455mm chainstays.
The Topstone Lefty also has an 11 speed GRX 1x group, a carbon frame with 30mm of fork suspension and 30mm of rear leaf spring frame suspension, running on 44mm Mezcal 700c tyres. It can take 47c tyres in 650b mode, which would be awesome option for some riders. The head tube angle varies between frame sizes and ranges from 69.5 and 70.5 degrees. They have short 420mm chainstays.
Fun youtube bike review
Our first gravel bike, a Whyte Saxon Cross, ran with an at the time slack 70 degre head angle and mountain bike inspired geometry – long reach and a short stem. It was a little more limited with regards to rear tyre clearance and sp we usually ran 35c or 38c out back and something bigger up front.
Gravelling on our MTB’s is also great fun and oftentimes is a safer and a less limiting option, allowing for bigger tyres, lower pressures, flat bars for descents and a really wide range of gears. We’ll usually use fast rolling Mezcal XC tyres and not trail tyres to cover the ground quickly.
Gravel bikes for our gravel
Sometimes we could ride a Synapse fitted with large tyres and cover some gentle gravel and broken roads, sometimes we could ride a Grade, Topstone or even a full suss MTB and each would be better optimized for different kinds of trails, but what does a gravel bike made to cover the whole spectrum of our trails look like?
Gravel Frame Geometry
To cope with the steep climbs and descents, a slack head tube angle and a generous wheel base adds a huge amount of stability. We’d rather a bike with modern geometry too, that sports a longer reach without having really long chainstays, to maintain fun handling in every situation.
Our Perfect gravel geometry – is less than 69 degree head angle. Not so long back, this was rare even on an XC race bike (mostly 29ers), but the very latest XC bikes now boast 66.6 to 68 degrees, often dependent on fork length and travel. Around 430mm to 435mm chainstay length is the sweetspot. It's worth remembering that travel can affect the geometry when riding and putting a fork on a bike with a steep head angle will make it even steep under compression.
Gravel fork Suspension
Gravel bikes with suspension you may ask?
Well it’s already here, has been around for while and is likely to start trickling down from the few, mostly high-end gravel bikes that currently sport suspension, to more mid-level bikes.
Cannondale has is its 30mm Lefty Oliver fork for it’s gravel bikes and Ocho forks (80mm upwards) on its MTBs, as well a King-Pin frame suspension.
Specialized has its 20mm fork steerer and 30mm rear Future Shock suspension.
Fox makes 40/50mm gravel forks based around the FOX 32 MTB forks.
Rockshox make 40mm gravel forks based around the Rockshox Judy MTB forks.
Companies such as Redshift, Cane Creek and PNW offer ‘suspension’ stems and seat-posts that are popular with many gravel riders seeking to add more comfort and confidence to their riding via after-market accessories.
Our Perfect Gravel Suspension – lies somewhere between 50 and 100m of front fork travel, with rebound and compression (lock out) adjustment. The stanchions do not need to be the bigger and burlier type found on latest the crop of XC race machines, sporting 34 and 35mm diameter tubes from Rockshox and Fox, necessary to cope with increasingly technical MTB terrain and bike parks. We’d also like tune-able air springs and lightweight materials i.e. not steel or coil springs.
With the bigger tyres we’d recommend, we’re also happy to have no rear suspension to keep the bike and frame simpler, lighter and easier to maintain. Sometimes cheaper too!
Gravel Frame Material
For a racing gravel bike running skinny tyres on smooth gravel, we would recommend carbon if budget permits. But as we are also recommending bigger tyres, we’re perfectly happy with a modern aluminium frame, designed with flex zones for comfort.
Our Perfect Gravel Frame – we’re happy with premium aluminium and are not too worried about shaving a few extra grams of weight from the total ride package. We’ve already saved a few grams by omitting rear suspension.
Gravel Tyres We want 700c diameter, bigger volume tyres and don’t mind a small increase in rolling resistance and weight by choosing a size, compound and tread that allows us to run tubeless at lower pressures, without rim protectors. We’d also spec a different tyre on the front than on the rear. The rear needs to be fast, the front needs to offer a little more traction. We also only like tubeless setups on bigger tyres, but find them not worth the hassle on smaller tyres e.g 35c or smaller Our Perfect Gravel Tyres – on the rear we’d opt for something from 47c to 2.1” inch, so either Mezcal or Terreno Dry tyre or similar. Up front, we would run anything from a 2.1 to 2.3 Mezcal tyre or similar. Tan wall's are a bonus.
Gravel Groupset
It’s here where we struggle with much of what is available from the likes of Shimano and SRAM, suppliers of the most premium gravel groupsets. Gravel has evolved and is continuing to evolve from cyclocross and road gearing, where 46:36 and 50:34 double chainsets were the standard, paired with perhaps a 32-34 cassette to where we are today.
We now have 1x or 2x, but with a wider range of gearing than before, to accommodate most riders across more varied terrain. However, we feel it’s still not enough for many riders and nothing like the range previously offered and used by riders when MTB triples were de rigeur. For example in a 2X Shimano GRX system, the recommend max cassette sizes are 34T or 42T, although you can run larger quite easily in both options. However, neither is going to give you an easier gear that’s anywhere close to MTB 30T chainset and 51T cassette.
Let’s do some maths and look at what different combination of chainsets and cassette’s offers us.
* GI – Gear Inches calculated by Sheldon Brown - using 700c wheels, 170mm cranks. A bigger number is a faster gear, better for high speed riding. The lowest number number makes for the easiest climbing. What do this show us?
GRX gears don’t offer the super easy gears for steep climbs that Deore does
Go for GRX 2x - if top end speed probably on tarmac is of highest importance
GRX 1x – needs a 46T cassette to match GRX 2x easiest gearing
Go for GRX 1x if you don’t need a really easy gear or super-fast gear
Deore 1x / 34T offers a similar top end to GRX 1x but has much easier easiest gear
Deore 1x / 30T offers a similar top end to GRX 1x using the 12T (second smallest cassette sprocket) and the absolute easiest gear available.
Our perfect gearing?
We’d love something like a 24/40T 12 speed system with a tighter ratio cassette than 10-51. This doesn't yet exist ... but we've been experimenting with something similar on a 10 speed build.
Now of course there are pros and cons when looking at 1x and 2x, but all things considered, the Deore system is the only one that is going to be able to conquer the steepest climbs we have at our disposal and we’d gladly sacrifice a fraction from our top speed on the road in return for much less hike a bike. Your mileage may vary.
Dropper Posts
Entirely optional for a gravel bike! However, we’d be tempted with a PNW Coast dropper, that offers some suspension too. However, having a frame with provision for the internal cable routing for fitting dropper at a latter date would be most welcome.
Cockpit – flat bars or gravel?
We’ve got bikes with both and as far we’re concerned, it’s quite simple for off road riding.
Narrow road bars are not good off road, flared bars are better and flat bars are the best; significantly, better downhill and on technical sections. On the road, flared bars are less good than road bars, but better than flat bars. On a flat bar, we do like inner bar ends to give us another hand position and one that is a little more stretched out. But what about the area benefits? Well the faster you’re travelling the more important being aero is. If you’re Lachlan Morton, he’s riding an MTB with aero extensions when the course demands it. If you’re promoting gravel bikes on a Youtube channel, the usual form is to show that a rider putting out 300W FTP is going to be faster with gravel bars than flat bars.
However, even if you have a 300W FTP, chances are that your zone 2 is around 200W. Most riders have never raced ad are not putting out anywhere 200W at Zone 2 on a 4-6 hour ride. If you’re riding along at say 100-150w, speeds are much lower and all those purported aero benefits become much more marginal. It’s much more important to be comfortable on the bike, flat bar or gravel bar.
So what are the options?
Surly make a Moloko bar that’s popular in bikepacking circles. They also make an Adventure bar with drops, that uses MTB brakes, called the Corner bar. However, it’s very heavy and needs a 25.4 stem. Surly they'll release a light weight aluminium version compatible with a standard stem, as no one wants to run shims on an off road handlebar.
For us, we’re happy with a flat bar on a gravel bike that’s focused for more exciting trails and terrain. When there’s a lot of road or flatter terrain, we’re good with road or flared gravel bars.
Controls
We’re happy with Deore gears and a flat bar, so it should come as no surprise we’re happy with MTB hydraulic brakes. Anything more than 2-piston brakes isn’t necessary. A 160mm sized rotor is more than enough out of the back and 160/180mm is enough at the front.
Obviously with flared bars an STI shifter is necessary, but with our flat bar configuration a single MTB thumbshifter will do just fine and save a bit of weight.
Conclusions
Let’s summarise what makes a great gravel bike given our preferences and trails and what the criteria we are looking for.
The Cannondale Topstone Lefty is clearly a great match and meets many of the criteria. It’s still going to need a custom build, to add some easier gearing and will need 650b wheels to fit the biggest tyres. For many trails and many riders, it’s a great albeit expensive premium option.
The Cannondale Scalpel, as raced by Lachlan Morton, in both hard tail and full suspension options, is also another candidate and one which ticks every box short of the fastest speeds possible on the road and anyone's strong preference for STI shifters. Again, the Scalpel, especially with a signature Lefty fork will serve many riders on any gravel trail and most MTB trails too. If you’ve not tried one and would like one bike to cover gravel and serious MTB riding, there are few better choices on the market. Other brands premium 29ers include the Orbea Alma, Specialized Epic HT, Trek Super Caliber, BH Ultimate, Ghost Lector SF, Mondraker Podium and any other premium hard tail might be worth of your attention too.
A left field option would be the YT Szepter, which does tick most boxes including a premium carbon frame, suspension and a gravel 1x group with a slightly wider range of gears than a Shimano 1x GRX bike. If you’re not a bikepacking type and would like a gravel bike designed by MTB riders for MTB riders,, this could be the ticket. It’s also a great looking bike too and good value in comparison to other brands.
Obviously, a premium carbon hard tail 29er with a decent component spec is only going to be a little heavier than gravel bike, but with some sensible compromises on frame material and high end components, a good 29er will give you a fully a capable bike on gravel and XC trails at a much more affordable price point.
Our hardtail 29er gravel bike of choice is the Cannondale Trail SL. More specifically the Trail SL2. It comes in slightly lower and higher spec variants too.
Let’s have a look at components and overall bike specification. It has a premium light weight aluminium frame, made by the company with the perhaps the longest and most storied history when it comes to building aluminium frames. The frame itself is bang on trend, sporting a 68 degree head angle when paired with the supplied 100m forks. It’s also a boost frame, offering a thru axle 148mm rear end, 435mm chainsets, routing for dropper posts and hidden cables running full outers and a traditional BSA bottom bracket. In short, all on point for 2023 and into the future.
The fork is a Rockshox Judy Gold, which offers an improvement over the Judy Silver and Suntour forks found on many hardtails. This means you get snazzy black 30mm stanchions, aluminium fork uppers, compression and rebound adjustment, boost hub spacing and adjustable travel from 80mm to 120mm, in a package that’s significantly lighter than much of the competition and not much heavier than a dedicated shorter travel gravel specific suspension fork. The drive train is mix of 12 speed Deore and SLX, with Shimano hydraulic brakes. How do we make them a little more gravelly? Pictures to come .... Well, firstly we run gravel tyres that can be setup tubeless, as well as fitting inner bar ends and the option of a longer/lower stem. We also adjust the suspension travel with a gravel specific tune, resulting in a 69 degree head angle and a little more stiffness than would be case for MTB use. Apart from, not much else. Everything else is pretty much ready. It has room for two full sized water bottles unlike many MTB’s and the official description from Cannondale even lists its intended use for gravel roads and low impact trails. In short, it bridges the gap between the Topstone gravel bikes and the high-end racing Scalpel carbon hardtails, whilst being a significant step up In quality from many entry level hard tail bikes, in terms of frame and component quality. They’re absolutely awesome for a full day of gravelling on every single gravel trail we ride. As a hire bike platform, it’s a great option for us and we’re proud to offer them across the size range. We are also more than a little fond of the way they’re look. I midnight pearl finish, that sparkles when it catches the sun, it’s a stunning frame finish. For serious MTB trail usage, we’d run the forks at 120mm for more slackness and compliance, with fatter wheels, bigger tyres and a dropper post, but that’s another story for another day.
So for you and your gravel riding, do think about the trails that you want to take it on. If a roadbike with fat tyres works, go for that. If you need something more trail focused, consider some suspension, a dropper post, bigger tyres and possibly a 29er frame if you don't plan on much road use.