Deda Fast Pro Extensions

The Deda Fast Pro Extensions sit at the premium end of the aero extension market, combining a full carbon construction with an impressive range of fit adjustments and compatibility with electronic shifting systems. While there are a few compromises, they provide a highly adaptable solution for riders wanting to add an aerodynamic position to a conventional drop-bar bike.

The Fast Pro Extensions are supplied as a complete kit, with a range of optional extras available. The standard extensions use conventional end grips that are compatible with bar-end electronic shifters from most major manufacturers, while dedicated grips are also available for SRAM Blips – as fitted to our test setup – and Shimano SW-R9150 bar-end shifters. These 3D-printed grips position the shifters neatly and securely. Deda states that the Fast Pro is only compatible with electronic groupsets, although given the price point and intended market, that is unlikely to deter many potential buyers.

Only one extension length is available, although it can be adjusted between 330mm and 410mm. The standard kit includes a 60mm rise spacer set at a 30-degree angle, but alternative height spacers are available in 20mm increments from 20mm up to 120mm. Angle spacers are also offered, reducing the extension angle in 5-degree steps down to 10 degrees. These are optional extras, costing £40 per height spacer and £34 per angle spacer, meaning fine-tuning your position can quickly become an expensive exercise.

Included in the kit is a computer mount compatible with Garmin and Wahoo quarter-turn mounting standards.

The overall weight depends on the chosen spacer configuration and whether the extensions are trimmed to length. With the supplied 60mm spacer, computer mount, armrests and both SRAM Blips installed, the uncut test setup weighed 1,007g.

Weight is unlikely to be the deciding factor here, as the aerodynamic gains and increased comfort offered by the extensions will outweigh the penalty of a few extra grams for most riders. Lighter alternatives do exist though, including the USE Boost Bar clip-ons with carbon extensions, which weigh around 500g, depending on configuration.

Assembly is refreshingly straightforward compared with many other aero extension systems. One particularly welcome feature is that both the handlebar clamp and armrests bolt directly into the aluminium spacer, eliminating the need to use different bolt lengths when changing spacer height.

The circular handlebar clamp makes the Fast Pro compatible with a wide variety of handlebars. Deda states the diameter is 31.7mm, which is effectively the same as 31.8mm handlebars.

They are compatible with many of Deda’s own range – both road and gravel bars. The key measurement is the 19mm clamping width, which may limit compatibility with some integrated aero cockpits where clamping space is restricted.

For testing, I paired the extensions with a Deda Superzero RS carbon handlebar and a Syntace F109 aluminium stem, which provided just enough usable clamping area. Deda also shows the Fast Pro fitted to gravel bikes, reflecting the growing number of riders using aero extensions to improve comfort during ultra-endurance races and bikepacking events.

Anyone who has fitted adjustable aero extensions will know that achieving the ideal position can often be a long and occasionally frustrating process. Thankfully, the Fast Pro is easier to install and fine-tune than most.

The handlebar clamps tighten with a maximum torque of 6Nm before the height and angle spacers, if being fitted, are added. The armrests then bolt on top, with 12 mounting holes providing extensive fore-aft and lateral adjustment. The armrest brackets also allow the pad angle to be adjusted independently, making it easy to sit on the bike, experiment with different positions and tighten everything once satisfied.

Although Deda does not mention rotating the base clamps to alter the extension angle further, it would theoretically be possible. However, keeping the spacers vertical ensures the load is transferred directly into the handlebar and is likely to provide the strongest and most stable setup.

The armrest pads are attached using adhesive backing and align with the mounting holes to allow adjustment. One area that disappointed me was their thickness. The padding is minimal and on longer rides I could feel the bolt heads beneath my forearms. It never became painful, but it was noticeable enough to affect comfort.

Another small criticism concerns the open-top design of the height spacers. Depending on your chosen setup, they can collect water during wet rides. This was unavoidable with my preferred configuration because of the limited lateral adjustment available at the handlebar clamp. A simple cap or cover would have been a welcome addition and certainly neater than the electrical tape I eventually used to seal the openings.

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The extensions are only available in a maximum length of 410mm, with adjustment down to 330mm. To get a fit I was comfortable and happy with, I needed to mount the bar at the shortest setting of 330mm, which could mean that some riders might want a shorter setup.

For reference, my forearm measures 44cm from elbow to the tip of my middle finger. I suspect other riders would also appreciate the option of a shorter extension.

Conversely, I found the 3D-printed hand grips relatively short. They suited my riding position well, but riders with larger hands may prefer a longer grip area.

The SRAM Blip mounting positions are excellent, allowing easy shifting whether resting your thumbs on top or wrapping your hands fully around the extensions. The textured finish produced by the 3D-printing process also provides good grip, although adding bar tape would be straightforward if preferred.

The computer mount is also 3D-printed and features a removable insert that can be rotated between Garmin and Wahoo mounting standards. It works well with a narrow extension setup, although riders using a wider armrest position may find the mount sits rather close to the left armrest. Deda currently only offers one length of mount, and there are no aftermarket alternatives available to move the computer further forward.

With the supplied kit offering only either no rise or the 60mm, 30-degree spacer, I had limited opportunity to experiment with fit. Fortunately, the standard configuration proved very comfortable and closely matched my preferred riding position.

Given the £505 asking price, however, it would have been nice to see at least one additional spacer included – perhaps 20mm or 40mm – to provide more flexibility. As mentioned above, the cost of height and angle spacers means the cost of optimisation soon escalates.

Aaron previously reviewed the FastTT aero bar system, which retails for $1,095 (around £830) and offers extensive adjustment and customisation.

While basic aluminium clip-on extensions remain available for under £100, including Deda’s own Parabolica Uno at £105, the market has shifted significantly towards highly adjustable, premium carbon systems costing £1,000 or more. The AeroCoach Ascalon is another example, offering extensive customisation and multiple mounting options for different bikes.

Although the Fast Pro has a handful of minor shortcomings, it is ultimately an extension system that proved exceptionally comfortable during testing, and fortunately, the standard spacer height suited me perfectly. The additional spacers arguably should be included at this price, but even so, the Fast Pro remains competitively priced against many comparable full-carbon systems.

If you’re looking for a fast, comfortable and highly adjustable aero extension system for a standard drop-bar handlebar, the Deda Fast Pro is among the best options available. It’s undoubtedly a significant investment, but it compares well against similarly equipped rivals and is one of the few premium aero extension systems equally suited to both road riding and off-road gravel events.