I've got a single speed and recently someone gave me some nice clip on aero bars. My bull horn handle bars are 26.1mm and the clip ons are for a 31.8 bar. Any way to shim the bars so I won't have to change them out? Ghetto style is fine with me-I'm cheap.

Use any handy thing you've got about for the shims as long as your ghetto is lined with foam... Ever seen what happens after a handle bar slips? There are proper shims for this purpose, I highly recommend that you use them. Or better yet just sell the wrong size bars and get the right sized ones. Lastly don't space out while on the aero bars, I have known a few riders how have found themselves on the ground and still don't know why. Andy.

I'm a bit confused by the post. Have you actually measured anything?

I ask because clip-on bars are usually mounted so the clamps are about 6" apart, or roughly 3" from center. That's beyond the clamp bulge, so both 26mm and 31.8mm bars would have already been reduced to the grip/brake clamp diameter of 15/16" (23.8mm), and that's what the clip-on bar clamps would be.

As I said, I'm confused as to why you think they need to be shimmed.

this might work or something like it. they come in various inside and outside diameters.

Doesn't have to be. I have a Profile Design Base Bar that's 26.0 mm all through the flat section where some aero would clamp on.
But shim to 31.8, yeah, can't see the need for that.

Which is why I said usually. The OP has to measure both the clip-on kit and the specific bars because there are many possible variations in both clamp position (distance from center) and bulge length and taper zone.

I thought that your "usually" referred to the spacing between, and the positioning of the aero bars, not all the possible variations in diameter.
My point was merely that there are bars - like my Profile Designs Base Bar - that are a uniform diameter from stem clamp all the way out to the horns. No bulge, no taper anywhere along the potential aero bar clamping section.

[QUOTE=FBinNY;17629106]I'm a bit confused by the post. Have you actually measured anything?

I ask because clip-on bars are usually mounted so the clamps are about 6" apart, or roughly 3" from center. That's beyond the clamp bulge, so both 26mm and 31.8mm bars would have already been reduced to the grip/brake clamp diameter of 15/16" (23.8mm), and that's what the clip-on bar clamps would be.
I obviously am not the best mechanic out there or I wouldn't be asking a stupid question like this. I tried to mount the clip ons on my handlebars and they will not tighten down nearly enough. My handlebars are 26mm. I know I could change the bars out relatively cheaply, I was just trying to find a way to make it work. I asked a mechanic at the bike shop and he said they usually shim it with something like another poster mentioned, but they are $15 apiece and they didn't have any. He said some people shim them with an aluminum (soda) can-honestly. I am pretty experienced with using aero bars. I have a TT bike and have done triathlons and many time trials. I'm not gonna be racing on the SS, just looking for a way to get in a different position occasionally. I'm doing a cross state ride in June (300+ miles in 3 days) and I'm doing in on the SS.

Yes To do the Math you must have numbers.. Measure .

take the outside diameter of the handle bar where you want to mount the aero bar .

subtract that from the inside diameter of the Aero bar clamp, then divide that in half..

that number is how thick the shim material must be..

maybe a section of aluminum tubing can be found with the right wall thickness , to use as that shim stock.



A digital caliper is very useful , and the china made ones are cheap enough..

i once cut a couple of 1 inch pieces off an old handlebar, then cut them lengthwise, giving me four pieces. i flattened them a bit and used those as shims. it marred the bar a bit, but the aerobars (Profile "jammers") held well enough on an 8 day singlespeed tour. good luck.

Ask at your local Trek shop or similar brand bike shop. They sold aero bars with 26mm shims for their 31.8 bars which were generally discarded. Or there are certainly Problem Solvers shims available.

However, you should really consider why you want them on your bike, outside of free take-offs. For comfort? Bzzt -- get your bike fitted. For speed/aero? Bzzt -- you ride a single-speed and are very often not operating at optimum efficiency where aero bars would boost that.

Sell them off on CL and invest than cash elsewhere.

+1. Andy.

Shims: I am not going to comment on your desires - that is your choice. I purchase aluminum tubing from Online Metals Order Aluminum 6061 Tube in Small Quantities at OnlineMetals.com to make the various shims I need - mostly front derailleur. Cut to length, then in half along the length to split the shim. A bit of very thin double stick adhesive holds them in place during the clamping operation.