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Thomson's Carbon Dirt Drop bar is light and stiff, but for me the drop position – which on a bar like this is much more about control than aerodynamics – is a bit too low.
Like most things Thomson, this is a very nicely made handlebar. It's made from Toray carbon fibre and uses 'tailor-made Nano Epoxy Resin for very high impact resistance', which will please you when you're binning it on a loose gravel corner, although as it's £230 you'll probably be hoping you stay rubber side down.
The bar is pretty light at 294g for the 44cm width that I tested; it's also available in a wider 46cm width that's about 10g heavier. It's internally routed with ports for hoses and shifter cables on opposite sides, and you can use it with a Di2 bar-end junction box too. There's a textured section where the levers sit to give them a firm grip on the bar when tightened.
Shape-wise, it's quite long on the tops, with a reasonably sharp transition to the hoods. It's designed to be 31.8mm diameter for as long as possible along the top, and that gives you bigger than average real estate for GPS computers and bar bag straps and lights and the like. It also means it's a bigger bar to hold there, which I preferred, but I do have enormous hands.
The drops are a 25-degree flare, which is about what I'd want, and the 90mm reach to the hoods is a bit more than I'm used to, which would probably make me dial back the stem length by 10mm to keep my usual position; the reach on my normal gravel bar, by comparison, is 76mm.
The drop to the bottom position on this bar is 130mm, and I'd say that's a bit too much for this type of bar. To put that into perspective, Salsa's Cowchipper has a 116mm drop and Ritchey's WCS Venturemax 102mm. The Venturemax is my go-to bar on a gravel bike, and the lower position is mostly for comfort and control. Let's face it, on an endurance geometry bike, with a 44cm bar with a 25-degree flare, you're not going to be that aero however big the drop.
If you're genuinely racing the gravels and you want a lower position to hunker down into then this might do the job, but it you're concerned enough about aerodynamics for that to be the case then you'll probably be speccing a narrower, less flared road bar, and sacrificing a bit of the extra control a gravel bar gives you for a nudge of extra speed.
The deeper drop doesn't really affect my ability to reach the levers for control on steep or technical stuff, although if you have smaller hands than me then the levers are marginally further away.
I got a position I was pretty happy with in the end by angling the bar so that the drops were slightly north of horizontal (don't tell the rule nazis), and fitting the levers quite high, at the top of the textured mounting section, to shorten the reach. The long 31.8mm section on the tops makes the bar pretty stiff, which is good for control, but means it's not the most comfortable; it benefits from a nice plush bar tape over the top.
You can spend a lot more on carbon gravel bars, for example the Enve G-Series is £360, though the carbon version of the Venturemax is just £20 more at £250. Both are significantly lighter, and the Enve that we tested is more comfortable, with a less aggressive drop shape. If you're looking for extra stiffness and a more aggressive drop position, though, the Thomson might be just the ticket.
Overall, I've been getting on pretty well with the Dirt Drop Carbon bar, but given the choice between this and my alloy Ritchey WCS VentureMax for mixed surface riding I'd definitely go with the latter. It's a better shape for off-road control, it's more comfortable and there's only about 50g in it weight-wise… and you’d save a stick of cash.
Light and stiff gravel bar for good control, if you like a deep drop
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road.cc test report
Make and model: Thomson Carbon Dirt Drop Handlebar
Size tested: 44cm
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Upgrade, Thomson's UK distributor, says, 'Carbon Fibre drop bars bring the performance and dependability you have come to expect from Thomson. The lineup is available in 3 profiles and varying widths, each made from Carbon Fibre produced by Toray and uses tailor-made Nano Epoxy Resin for very high impact resistance. The Carbon Dirt Drop bars are available with a mild flat, a round profile, or new to Thomson, the Flared Drop bar. The Dirt Drop shares a similar top to the round road bar, measuring 31.8 as wide as possible. Each profile has exceeded the ISO 4210-2:2015 requirement.'
The Dirt Drop is available in 44cm, and 46cm, with 25° flare, Drop 130mm, Reach 90mm ready for your next adventure, regardless of the road you choose.
Tell us some more about the technical aspects of the product?
* Available in 44cm and 46cm widths.
* 130mm Drop.
* 90mm Reach.
* 31.8mm Clamp.
* 25 degree Flare.
* Toray grade Carbon Fibre.
Tell us how the product performed overall when used for its designed purpose
It was okay but not ideal in terms of bar shape.
Tell us what you particularly liked about the product
Light, stiff, plenty of places to put things.
Tell us what you particularly disliked about the product
Expensive, drop is too deep.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
Not cheap, sure. But a lot cheaper than an Enve G-Series bar (£340) or a Ritchey Venturemax WCS Carbon (£250).
Did you enjoy using the product? Not my favourite bar, but we're getting along okay.
Would you consider buying the product? No
Would you recommend the product to a friend? Maybe, if the shape suited their needs.
Use this box to explain your overall score
An interesting bar, but for me not quite as well suited to the job it's being asked to do as some of the other options out there. Your mileage may vary, of course.
About the tester
I usually ride: whatever I'm testing... My best bike is: Kinesis Tripster ATR, Merida Scultura, Dward Design fixed
I've been riding for: Over 20 years I ride: Every day I would class myself as: Experienced
I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, club rides, sportives, general fitness riding, fixed/singlespeed, mtb, Mountain Bike Bog Snorkelling, track
Dave is a founding father of road.cc, having previously worked on Cycling Plus and What Mountain Bike magazines back in the day. He also writes about e-bikes for our sister publication ebiketips. He's won three mountain bike bog snorkelling World Championships, and races at the back of the third cats.