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To disc or not to disc

Old 01-07-11, 06:39 PM
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To disc or not to disc

The guy at my running shop told me that I must get a rear disc because the difference it will make is huge. I won't buy a wheel but a cover from wheelbuilder is doable. Convince me that it is $90 well spent
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Old 01-08-11, 12:22 AM
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It is.
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Old 01-08-11, 12:40 AM
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compare it to what you could get for 90 bucks. tires? water bottle cages? i would say for 90 bucks why wouldn't you?
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Old 01-08-11, 01:31 AM
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For what race? Sprint? Not so much, Iron man, oh yea!
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Old 01-08-11, 12:09 PM
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Why the difference, you think that the time savings are just too minimal at the Sprint distance. For the record, I'll be doing Sprints and an Oly this year.
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Old 01-08-11, 12:15 PM
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Dude..the wheel cover is as about the cheesiest thing ever........get good wheels or save your pennies for the $1k needed for a disk....unless your a cycling beast save the $90 bucks for tires, gel, tubes & sun block..


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Old 01-08-11, 12:17 PM
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I haven't seen one in person, but cheesy?
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Old 01-08-11, 04:31 PM
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hammerdog...have you seen the wheel covers from wheelbuilder.com? Definitely not cheesy and tested better than the Zipp disc in '09. The only thing you get with that extra $900 is the cool disc sound.

Oysterboy...I'd agree that a disc isn't going to make much difference in a sprint and would only worry about it if you need to eke out every second in order to make the podium. It will save you some time in an Olympic and once you get to Half Ironman, it can add up to some good time savings.
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Old 01-08-11, 07:10 PM
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I am sorry......I never saw this cover before...Not bad. I recall the old school 90's cloth version.....I may just get one for my Tri bike. I run Rolph Vector pro's and these would look cool.

https://www.wheelbuilder.com/store/aero-disc-covers.html
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Old 01-08-11, 10:22 PM
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get the cover, but be sure there are not predicting high winds on race day!!!! have you noticed why the pros are not using disc wheels in KONA...its because of the winds...but 90 bucks well spent otherwise
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Old 01-09-11, 06:04 AM
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Originally Posted by spinalrx
get the cover, but be sure there are not predicting high winds on race day!!!! have you noticed why the pros are not using disc wheels in KONA...its because of the winds...but 90 bucks well spent otherwise
No, it's because disc's aren't allowed at Kona, regardless whether they are pros or age groupers.

The disc is faster regardless of what speed you are doing or distance the bike leg. As cjbruin has already alluded to, a well fitted disc cover is as fast as a regular disc.

As to managing a disc in winds, your weight is more over the back wheel. Unless you are a super flyweight the disc is fine to control in most winds, it's the front wheel you have to worry about in blustery winds... Since getting a disc back in 2001, I have not raced a tri or road TT without the disc on the back and this has been in some nasty conditions. It's only the front wheel I swap out from the Stinger 90 to a Zipp 404 if the winds are really up and gusting.
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Old 01-09-11, 07:11 AM
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Originally Posted by Dalai
No, it's because disc's aren't allowed at Kona, regardless whether they are pros or age groupers.

The disc is faster regardless of what speed you are doing or distance the bike leg. As cjbruin has already alluded to, a well fitted disc cover is as fast as a regular disc.

As to managing a disc in winds, your weight is more over the back wheel. Unless you are a super flyweight the disc is fine to control in most winds, it's the front wheel you have to worry about in blustery winds... Since getting a disc back in 2001, I have not raced a tri or road TT without the disc on the back and this has been in some nasty conditions. It's only the front wheel I swap out from the Stinger 90 to a Zipp 404 if the winds are really up and gusting.

I stand corrected....i guess I misunderstood an interview I watched with Macca or another pro this year on this years coverage!!...thanks
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Old 01-10-11, 05:52 AM
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coincidentally in this months Triathlete magazine there is a supplemental section regarding the ironman and half.

They discuss the disc wheel issue. It is correct that disc wheels are not allowed, but they state the reason the rule is in place is due to the high winds that can blow the rider to the otherside of the road
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Old 01-10-11, 05:29 PM
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Yes, Kona can have exceptional winds across the exposed lava plains. Even though some riders would be still able to control their bikes with a disc on the back even there, it is simpler from a safety perspective to just ban the use of the disc for everyone...
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Old 01-11-11, 03:26 PM
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You want a disc because you want to go faster. Great. Lots of other ways too - primarily your position (flat back, can you comfortabely stay in aero?), fast tires and tubes (Mich ProRace and latex tubes, for example), an aero helmet, tight-fitting clothing.
Oh, and your engine. Always work to be done on the engine!
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Old 01-12-11, 06:10 AM
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But to go faster, the disc and other equipment or positional changes are not mutually exclusive. Agreed the rider is estimated to account for 70-80% of the total drag, so getting a comfortable (no point going with a super aggressive position if you are forced to sit up for half the bike leg) optimised aero position.

Although a disc on it's own is suggested to save ~30 seconds over 40km, a wheel cover is a cheap investment and the sum of all the little changes can add up to a considerable saving in time / watts required on the bike.
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Old 02-22-11, 06:58 AM
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May I ask..

I'm pretty new to this kind of riding but from what I've seen, disc wheels are more popular in time trial events not ironman or triathlon events and why is that? Or it's just my misunderstanding? Please advise..
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Old 02-22-11, 02:34 PM
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In general it's due to misunderstandings and misconceptions. Lots of triathletes are told discs are too heavy, hard to handle, or uncomfortable or not fast because they don't go fast enough. In general though:
1. a disc's extra weight is far exceeded by the increased aerodynamics.
2. A disc is generally(at most wind speeds) handling "neutral" because it actually pushes the person against the steering axis, so in essence when your disc gets "pushed" by the wind it is counter acting the effect. In REALLY gusty conditions, discs can be more hard to handle but I do mean REALLY GUSTY.
3. Depending on the disc, it may be more uncomfortable but it's negligible.
4. A disc helps people at slower speeds as much as a person at faster speeds. Only down around 12-14mph do the aerodynamics become negligible.

So what you've seen is probably correct, i.e. road riders ride discs more often. However, I would say there is not a good basis for this difference.

Also, two ironman races don't allow discs due to conditions. Ironman Hawaii and Ironman in Mexico. These races tend to have conditions on the gusty side. It's probably not necessary but if everyone is penalized equally, it works out in the end.
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Old 02-23-11, 11:48 PM
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I wasn't aware IM Mexico also didn't allow discs.

Another possible reason you won't see as many discs at IM's is quite a few competitors will have flown to race. Easier to just carry two wheels rather than three just in case it is on a very rare off chance too windy to ride it...
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Old 02-26-11, 02:16 PM
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Not sure if it's IM Mexico. I should have been clearer; an IM owned event in Mexico, could be one of the 70.3 races.
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Old 02-28-11, 05:53 PM
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IMV discs are excellent - for elite athletes. If you're looking for gains of seconds against a tight field and you've maxed out other options, go a disc when conditions permit. Otherwise, just have good quality wheels that are well maintained and pumped up.
Moreover, learn to be a better rider; more flexible with a lower riding profile. Various people that I've read and spoken to estimate that once you're moving over 30km/h, 80% of your effort is wind resistance and the bike is 10% of this. Spend the $900 on a personal yoga trainer so that you have the core/lower back flexibility to hold a cancellara/contador/evans/zabriskie/martin-like riding position for several hours. That is where you'll gain speed & time. Minutes and minutes. Whats more, your running will be better too as you won't be nursing a sore back.
30 sec gained with a wheel cover is lost if you can't get your shoes on first go.
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