Vision is a perennial name in the aerobar game. I speak from experience as an early adopter of their products, starting with their early-generation clip-ons in the early 2000’s. I remember seeing their bars being used in route to countless victories by Team CSC in the ProTour circuit. Vision was at the tip of the spear, with products such as their full integrated aerobars (including an integrated stem), their mini ‘crab claw’ brake levers, and their mini aerobars for road bikes and draft-legal triathlons.

One of those products, in particular, has been an interesting category for Vision: aerobars with an integrated stem. If it’s not self-explanatory, bars like this are made as a single piece, with the stem molded, cast, or welded right in. This is a source of great controversy and heated debate. Stems are an important tool for properly fitting a bicycle to the rider. If the handlebars are too close, install a longer stem. If the handlebars are too far away, install a shorter stem.

However, that’s a reductionist view that doesn’t quite apply to triathlon bikes. For a road bike, the stem IS your reach adjustment mechanism. For tri bikes, there’s a lot more going on. Your reach to the base bar (a.k.a. pursuit bar) isn’t a tremendous deal. We’re more concerned with the specifics of the aerobar pads and extensions. If an aerobar has an integrated stem, but builds in massive amounts of adjustability elsewhere for aero extensions and pads, you’re probably just fine.

Why bother with the integrated stem at all? It’s an aesthetic thing. It might lead to tiny improvements in aerodynamics, but this is an utterly insignificant issue for 99% of the buying public. Even if that air flows slightly smoother over a clean integrated stem – it’s heading right for a large, turbulent human body with moving legs.

Vision offers aerobars with an integrated stem, such as the Metron TFA. This bar has a very wide range of fit – but what if that’s just not enough for you? Or what if you’re just not sure, and want to take every precaution to be sure that your new aerobar investment will absolutely fit?

Chuck the stem. Get the new Vision Trimax Carbon SI 013.

What we have here is essentially a new version of the TFA, minus the stem. It works with any 31.8mm stem, including the Vision ACR system. The ACR family is interesting in that it gives you an integrated “system” without actually making the stem a permanent fixture.

Take a look at my sample bar above. There is a hole right in the center of the stem clamp area – this is what makes it work with the ACR system. The cables route through this hole and into a ready-made stem, for a completely hidden look.



The video above shows the highlights of how ACR works. If it’s not obvious from the video, Vision makes road options and full integrated stem options for ACR, too. The point is that the cables make their way through the stem and into the frame, without seeing the light of day. Note that the Si 013 doesn’t require that you ONLY run an ACR stem. You can run a standard stem, too.

By the way, I’m going to point out our collective need to say ‘thank you’ to aerobar engineers across the globe. Slowtwitchers tend to think from a bike fitter’s lens. The bars must fit a wide range of people. However, the engineers of these bars must put an equal emphasis on compatibility with an insane array of drivetrains, brake systems, brake levers, frames, headsets, stems, battery and junction box placements… and probably more things I’m not even thinking of. The fact that anyone pulls this off is a small miracle.

There are three extension options with the Si 013, seen above.

My bars came with the JS bend, which I imagine will be popular, along with the J-bend. I’m a traditionalist when it comes to aero extensions, and none of the straight or s-bend styles have ever worked for me.

The extensions and arm pads angle together up-to-16 degrees.

You want spacers and bolts? You got ‘em.

The instructions include a handy table to help you select the right parts for your particular arm pad stack height.

The arm cradles have a large surface area and a bevy of mounting holes.

The ‘wings’ on to which the arm cradles mount may be flipped forward or backward. The mounting holes allow for a huge range of possible positions, and up-to-13 degrees of angle adjustment.

They also have a very detailed PDF hosted online with several detailed fit charts – too numerous and extensive to list here. If all the numbers seem overwhelming to you - that's what you pay a bike fitter for.

The above chart shows the basic specs that you or your bike fitter will need. Quoted weight for the bar is 695 grams without armrest spacers.

The Vision Trimax Carbon SI 013 bars are available now. They come in at $600 USD, or a savings of $250 compared to the TFA with integrated stem. This tells me that, unless the TFA comes stock on your bike or you just gotta have that integrated stem, the SI 013 is the bar for you. I’m looking forward to getting more familiar with these bars, and the fit options that they have to offer. Learn more at the Vision website.