Profile’s 43 ASC Comes in a Second Length

September 19, 2023

Profile Design now has a second size of its 43 ASC extension. Let me tell you why I think this is a big deal.

What we want in an extension is to rest our forearms along its entire length, or as close as possible to it. Among the most ergonomic I’ve used are these, and ergonomics are the point. These extensions – all of them, from all the companies – look more aero and they might be. Or not. But what we can know is that they’re a lot more comfortable.

This new style of extension comes in 2 mounting formats. One style has the armrest pad and the extension all in one piece. The other style is what you have here with Profile Design and it’s very typical of what you’re used to. You have a bracket that attaches to a pursuit bar, the pad attaches to the bracket, and the extension separately attaches to the bracket. The reason this is important is that many or most of you buy your tri bikes assembled, compete, and they come with “original equipment” aerobars. They almost never come with that first kind of full forearm extension I described above. They’re likely to come with typical aerobars with round extensions of some shape or another.

Because these 43 ASC extensions mount into the typical clamp that we’re all used to, you can use these to convert your existing tri bike front end into one that has a full forearm rest.

If you don’t have these, then you need an adapter plate of some kind to get that super-duper sexy system onto your bike and that’s not always easy; it takes a lot of McGuyvering; and are you sure that your bike is engineered for that cantilevered weight once you get that system on it? Mind, I’m not throwing cold water on Drag2Zero, Sync, AeroCoach and similar systems. It’s just that we’re in kind of a transition period right now where we have bikes, and we have these new cool aerobar systems, and we don’t have a blueprinted system of getting all these bars onto all your bikes.

But the 43 ASC had one problem: it was one length. Now there is a shorter version, at 340mm, to go with the original 400mm. The angle is the same; the difference in the long and short extensions is between the forearm and the wrist. I do believe the round hand-hold piece has gotten longer, a running change in all the extensions Profile will release of this style, to accommodate the (badly conceived) carrier for the (well conceived) SRAM Wireless Blip. This makes the handhold too long in most cases for most uses, but you cut it to length (miter block, Sawzall, done).

This is a particular boon to certain proprietary systems that need that 43 ASC to be shorter, notably the tri bike by Kú Cycle. That bike has its own bracket system and you must (as of this writing) slot in a set of round extensions. If you want a full forearm rest you’re limited to the Profile Design 43 ASC, but that clamp system from Kú Cycle (above) sits "proud" of the armrest (sits several cms forward of the pad). That made the 43 ASC too long for most folks, though it worked for me and I’m 6’1” tall. This new shorter version of the 43 ASC will make the Kú system work with this extension for 90 percent of the buying public rather than 30 percent of it.

As a bonus, the MSRP on these extensions has gone down. When I first reported on these the price was $300 a pair. You’ll see these on Profile Design’s website now for $285 a pair. The good news is, they have these in stock. The bad news is, I don’t see the new shorter versions listed anymore on the site. Check this brand’s official fit assistance thread on our reader forum for forecasts on when the shorter version will be back in stock in the U.S., and/or where you can find it in stock.