nitewing117

Since the weather has been nice, I recently began commuting to the office twice a week with my Specialized Tarmac. The route I take is 25 miles one-way but is 80% bike path and with the only grade being a long bridge. I don't carry a backpack or any work related clothing since I store spare sets of clothes, shoes, and my laptop at work. I thought that maybe I could save some time and energy if I got an aerojacket from wheelbuilder.

Are there any negatives to running a rear disc cover that may be commuter specific? I'm relatively new to commuting and cycling as a whole, but I've read that there are a good amount of savings to be had from aero.

Leebo

Pics please? A solid wheel cover? Good luck with side winds. The bike path is not for racing anyway.

tjspiel

Somewhere on the interwebs is a list of cycling related time saving items and what each item would potentially save you on a 40k time trial. Everything from shaving your arms and legs to shoe covers.

I can't from memory tell you what a rear disc wheel or cover would save you but it's in the range of seconds, not minutes. It could be critically important in a race. Could mean the difference between reaching the podium or finishing back in the pack of also-rans. For a commute though it's probably not worth worrying about.

Edit: This may have used the same source and the page where I found it has other info, but this should give you an idea:




Interesting that a front tri-spoke saves more time than a rear disc. If you add it all up, it makes a significant difference, - depending on what you think of as significant. Whether it's worth it or not is another question.

DiabloScott

Do you consider being mocked relentlessly by other cycling commuters to be a negative?

nitewing117

I'm sort of expecting it. I'm a recreational road cyclist that just so happens to ride to work which is why I posted this question here. I see it less of a commute or race and more of a training ride that happens to get me from home to work.

Wilfred Laurier

The one major drawback that should not be glossed over is the effect of sidewinds on a disc wheel. Strong sidewinds can make the bike unrideable.
Also, the chart above gives the potential benefit for an elite racer at speed - for a commuter on a bike path you are not going as fast and will not get nearly the same advantage. And if you are going fast enough that you will benefit from a disc wheel, you shouldn't be on the bike path. And if you are on a road with car you should definitely not have a disc wheel because of the effect of side winds..

If you are concerned about maximising your aerodynamic efficiency and speed, a clip-on aero bar (even the cheapest and ugliest ones) will make a much bigger difference than a disc wheel.

Bandera

Like locking a rear wheel w/ a disc cover installed?

-Bandera

nitewing117

In retrospect, I should have posted this in the tri subforum since I just realized that I treat this more of a training ride than a commute.

Andy_K 

The time effect on a commute will be negligible. You'll probably use slightly more energy with the disc cover since you start and stop a good bit while commuting and the disc fairing represents extra weight that you need to spin up each time (not a factor in time trialing).

Probably the biggest benefit of using the wheel, from a training perspective, is that you'll get that many more miles to adjust to the feel of riding with that wheel.

caloso

I also use my commute as training time and I've occasionally ridden my race set-up to work. Like if I've just glued up some new tubulars, I'd rather check the glue job on my Friday commute than during my Saturday race. And I know guys who occasionally ride their TT bikes on the commute, mostly to just spend time getting comfortable in an aero position. But other than checking out handling, I don't think there's that much benefit to using a disc wheel or wheel cover on the commute.

nitewing117

There's actually only about 8 stoplights in the whole commute, with 5 of them being within the first 5 miles and the remaining in the last 2. Thanks for the training perspective tip - the seat time with the wheel is probably worth it.

Andy_K 

It's definitely in the realm of negligible, but I would guess that spinning that wheel up 8 times uses more energy than its aerodynamic benefits save you (both being very small numbers).

jfowler85

Concur. Is this a MUP you're riding? Are others present? That's not particularly responsible on a MUP to run at such a speed at which aero canards are beneficial.