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The context here is an endurance setup, with a fit optimised for the hoods/drops. Clip-on aerobars are being fitted to give an additional hand position especially into sustained headwinds; this very different position relieves pressure and stress on the hands and wrists. We (it's me helping a friend - I've done my own by trial and error) don't want to compromise the rest of the bike fit, which was done professionally, and which will be applicable for the majority of the time.

I've seen some advice about height (example, but that's in a TT or tri context, aero above all else, to the extent that they recommend a reduced crank length so the knees don't come up as high. Even then they don't say much about the reach on the aerobars (when that's adjustable without changing the stem). I know from my own recent adjustments putting mine out too far that it can be quite important, as my thighs contact my ribs.

For other aspects of DIY bike fitting there are plenty of more-or-less accepted approaches, but what about for aerobars, whether that's for endurance or a TT novice? I know a bit about the principles (I discuss them in an answer along with some more details on my setup) but wonder how to match those principles to a user. We don't have a turbo trainer available, but have good roads for test-riding, and I'd be interested to hear if trainers added something significant.

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  • I suggested a title clarification, but feel free to refer the edit if it doesn’t convey your meaning.
    – Weiwen Ng
    Jun 16, 2022 at 10:05
  • Thanks @WeiwenNg - I didn't think about non-clip-on ones having never used them. Anyway a reader can often bring more clarity than an author with a narrow view.
    – Chris H
    Jun 16, 2022 at 10:41
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    It’s more about indicating that you are asking about aero bars on a road bike, as opposed to a dedicated tri/TT bike.
    – Weiwen Ng
    Jun 16, 2022 at 12:50

4 Answers 4

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For clarity, the OP is asking about fitting clip-on aero bars to an endurance road bike. I have no personal experience with this.

I will say this: there are at least two relevant parameters. One is the bar's length. The other is the stack height, i.e. how far above your handlebars are the elbow pads. Here, it's possible that lower may not be better, based on this post by Torsten Frank where he addresses their use in ultra-distance cycliing. Basically, too low a stack height may mean you have to lower your torso angle in the aero bars, and this could strain your upper arms (supporting the body), and change the angle of your neck. I believe he advocates a slightly higher stack height for the bars.

It's true that all else equal, a higher torso should equal a higher coefficient of drag area (CdA). However, with aero bars, you are also putting your arms in a narrow position and you're shielding your forearms from the wind. And if you are thinking about long rides, comfort is a higher priority than it would be in a time trial (to be fair, comfort in an Ironman tri bike leg is also a very high priority).

One unmentioned point: many long-distance riders may stash snacks in handlebar bags. Aero bars block your access to most handlebar bags. I know that Apidura makes handlebar bags compatible with aero bars. This isn't a product recommendation, it's merely one brand I'm aware of.

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  • The bit about the Ironman bike leg is slightly subjective. It holds true for an amateur looking to survive inside the time cut. However the top male athletes are completing the bike leg in around 4 hours so comfort isn't really much concern.
    – Andy P
    Jun 15, 2022 at 20:36
  • I've just come indoors from fitting one set of bars to the brackets from another, because those brackets had 30mm spacers to raise the stack. The specific issue here was more one the back than the arms (though I need to undo the last adjustment to my own setup for the sake of my arms (possibly also my neck though I didn't use them for a long enough stretch at the weekend, riding in company)
    – Chris H
    Jun 15, 2022 at 20:52
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    When I used my for a 1200km tour in just over a week, I had a bar roll, but my accessible snacks were in a toptube bag and one of two stem-mounted bottle bags.
    – Chris H
    Jun 15, 2022 at 20:54
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Decent aerobars offer many degrees of adjustability. You can move the elbow cups in/out and fore/aft (peel off the padding, and the cup base should look like a colander). You can adjust the reach and in/out rotation of the extensions, rotate the whole assembly up/down in front, and use spacers to raise the elbow cups.

Make sure to order a set of spacers. I started with no spacers on my aerobars and could only hold that position for 10 minutes. When I added 30-mm spacers, I could hold the position indefinitely.

Position the elbow cups so that your arms are supported near the elbows, and so that your upper arms are close to vertical—if your upper arms are reaching forward, that means you're doing more work to support your upper body, and you want to avoid that. Position the cups far enough outboard so that you can breathe comfortably—too close and your arms constrict your chest.

Now position the extensions so that you've got a comfortable grasp near the ends. Many aerobars are available with J-bend and S-bend extensions, and I prefer the J-bends myself. I also prefer to have the ends rotated inward at the top--it puts my wrists in a more comfortable position.

I prefer having the whole assembly rotated upward maybe 10° from horizontal, and some people have them angled up much more steeply. My impression is there's no aerodynamic harm to that.

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  • That's close to what we've converged on. Part of the issue is so many degrees of freedom, and limited long rides to try things out. But the spacers seem to be the big factor. I've got mine set a bit narrower, but because they're used at cruising effort it doesn't matter - I'm not breathing very hard when I use them
    – Chris H
    Jun 16, 2022 at 5:43
  • For height adjustment, I think the term riser kit may be more common than spacers for clip-on aerobars.
    – Weiwen Ng
    Jun 16, 2022 at 12:55
  • @WeiwenNg yes, a "riser kit" consists of risers/spacers, screws, and any other necessary fittings - you want the kit because you're not likely to have the screws lying around. We used this Profile Designs one specific to the brackets I had spare, though the bars and armrests are Zipp (the Profile Designs bars were too long and pulled back got in the way of stuff mounted on the stem, but the diameter is the same)
    – Chris H
    Jun 17, 2022 at 10:23
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I'll start with a disclaimer. I have no particular knowledge about fitting aero bars and have never ridden with them myself (although have used 'puppy paws' fairly often so do have a rough idea how it feels.

Given that your friend doesn't want to compromise the rest of the bike fit, we'll assume that is the 'gold standard' and they can comfortably get into all the 'normal' positions (tops/hoods/drops/aero hoods). I'd also assume for this type of event the aerodynamic objective is to get narrow and hide the forearms rather than getting particularly low.

I'd start by getting your friend to get into both the drops and aero hoods positions and measure the position of the elbows relative to the headset top cap (most likely a little above and behind). I'd aim to get the arm rests in a position where the elbows were in roughly the same place (but narrower) as those previous 'normal' positions.

I'd then adjust the bars themselves to a position where the grips felt comfortably in reach and not too stretched. Given we have already placed the elbows in a similar position this probably places the grip area a fraction beyond the hoods.

The end result will be a position that is slightly higher and narrower than 'aero hoods' but more comfortable to hold and with a more open hip angle allowing better power production. I'd say this position has a very high chance of being comfortable because it's putting the body in a very similar position to how it normally would be.

Using that as a starting point your friend could then experiment with a slightly more stretched position if they felt it was beneficial/comfortable. I notice the position you have adopted on your own bike is a little more aggressive/stretched than my fitting approach would come to.

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  • That sounds like a really helpful way to start, thanks. My own position has stretched out a bit as I've got used to them, but is probably a bit less aggressive than it looks bearing in mind that I can hold the tops under the armrests, and that I didn't really take the bar tape low enough so hold them lower/closer than you'd think. Recently I've stretched out a bit too much further and was having a bit of a thighs vs ribs issue at the weekend. I've also set them closer together - yet another variable in some cases
    – Chris H
    Jun 14, 2022 at 15:34
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I tried aerobars for a while - they were useful when on a long straight empty road. For any riding where there is traffic or people or turns, not so useful. Main problem is you're a long way from the brakes for safety, and from the shifters for undulations in the road.

My main problem turned out to be neck pain - it wasn't obvious while riding, but after ~30 minutes in the tuck I had problems looking forward. Even with the helmet tipped way back on the forehead, forward vision suffered.

My top considerations would be comfort and safety. Aero gains and speed are third, at best.


They do make an excellent platform for bikepacking light stuff like sleeping bags. I once carried a 1RU ethernet switch on my aerobars for a couple kilometres - why? My bag was full.

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    For long rides, those aerobars also provide another position, which can be enough reason all by itself to use 'em. Jun 15, 2022 at 23:20
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    That's very much my view, plus you can't use them close behind someone, and they're of limited use after dark. But they're still useful enough to be worth having when you're spending 12+ hours in the saddle on consecutive days. The load on your hands, arms, shoulders, and back is very similar in the drops or hoods, so an efficient comfortable position that's very different is the goal (yes, you've got the tops, good for a stretch but inefficient for long periods - and the stretch is better if you hold the arm pads of clip-ons instead of the base bars
    – Chris H
    Jun 16, 2022 at 5:51
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    Also I had some neck issues at first.
    – Chris H
    Jun 16, 2022 at 6:23
  • I've also been sketching a design for a pouch that sits on/between the aerobars but flaps out into a larger bit of storage - for use when bikepacking, when I might want to buy fresh/bulky food for dinner, ride to my night stop, then eat it. It's complicated by the fact I mount my phone (navigation) there, or I would have tried something by now
    – Chris H
    Jun 16, 2022 at 10:44

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