Alden Designs carbon fiber aero fairing for Quarq-SRAM S975 powermeter crankset

Alden Designs is a little one-man shop that makes custom carbon fiber aerodynamic covers for your chainrings and other parts of the bike.

Now, Glen and his son have expanded the offerings from his Columbus, IN, workshop to include a carbon chainring cover molded to hide the QuarqS975 powermeter crankset from the wind. As with the original, you can purchase a carbon shell and trim the holes and tap your chainring yourself ($50), have them pre-cut the diameter to fit anything from a 50 to 58 tooth chainring and cut the crankarm hole ($70) or send your crankset in and have them tap, drill and cut everything to fit so you only have to mount it back to your bike ($125 plus shipping).

The cover is held in place with nine stainless steel button-head screws, which allow you to remove the cover to replace the battery. Glen says you won’t need to recalibrate the power meter after installation. It’s made with standard 3K woven carbon and maintains a 1mm to 1.5mm clearance over the crankarm and electronics. The unit shown here is a prototype and final trim will have tighter tolerances.

Alden Designs carbon fiber aero fairing for Quarq-SRAM S975 powermeter crankset

Their molds provide a very smooth finish, then they apply a silicone shine rather than a clear coat. Their website says a clearcoat isn’t used anymore because the finish is good right out of the mold, and because some chain cleaners and other chemicals used down there can damage the clear coat.

Over the top? Perhaps. Competition legal? Maybe. Awesome? Absolutely. Check them out at


  1. Does this have to be carbon? There are no stresses. Couldn’t you do the same job with a $1 plastic dixie plate? Or is that not cool enough?

  2. @pmurf Man I’d take a mahogany laminate for my sweet classic fixie conversion. it’d be the perfect final touch for running red lights.

  3. @jimmy – You just don’t get it, do you boy?

    Go get the stick! Go get the stick! Who’s a good doggy? You are! Yes you are!

  4. I don’t like the thought of drilling a chainring, but the execution and finish are great. Item is really nothing more than a premium and most can’t be bothered unless there was a simpler install. Still nice.

  5. All, thank you for all the comments, some good, some not so good, input is good, that’s what drives new and improved products. Actually, a crank cover could be made of almost anything and still work. The hardest, most time consuming, and expensive part of the process is getting the mold tooling produced so that it is accurate to ensure everything will fit together well. Actually, if I could get a thin enough piece of wood laminate, I could make a cover, that might look pretty cool :o), or for that matter, almost any thin material. Carbon is nice as it only makes the cover weigh in at about 20 grams and is very stiff. Also, I am testing industrial adhesive back tape to hold the cover in place as well right now, I expect to have results soon , then this will truly be a plug and play product.

  6. lies
    UCI Illegal (although not sure how relevant ‘UCI legal’ is these days) and WILL change the structural properties of the chaining (although a small amount)

  7. Cool and good price. Needs simple plug and play (no holes in chainring)
    I dont get why not carbone fibers? all high end cranksets has that finish
    Maby price is too low !
    Check stupid lightweight seatclamp in carbon fiber for 50$(or more)

  8. I do not believe any one ever claimed it was UCI legal, it is certainly a fairing and if you were doing a UCI race they would probably take issue with it. Most people on TT bikes likely aren’t doing UCI races but rather triathlons, even if they do TT’s only nationals and a handful of TT’s in the US does it matter.

    Looks awesome, installation is a bit invasive and with the power meter battery changing is a bit of a pickle, but both can probably be solved! Thanks for the awesome products.

  9. Whats the measured aero benefit w/ a rider on the bike? Why would you bolt this on your bike w/ out knowing that? Seems unnecessary to me.

  10. Andy, based on research I performed a couple of years ago (before starting this project) for a variety of cranksets in the past (Zipp, FSA, and others), the claimed time savings over 40Km by having an aerodynamic cover on the crankset is anywhere from 30-45 seconds. The biggest time savings were for the higher yaw angle wind conditions. With this being said, and all of us looking for a little less drag, every little bit helps. I am hoping at some point soon, I will be able to get my cover into a wind tunnel so see what the real numbers are for my cover designs. Glen

What do you think?