Assuming an average speed of 20 mph on a relatively flat course would a disc give any real advantage over a deep rimmed wheel, say… a 404, on a non-aero frame road bike? I would think that the seat tube would be generating most of the drag and the rear wheel would just be sitting in its wake.
it won’t make you any slower… if you already have the disc, run it. If you are looking at buying one and trying to decide between the 404 type wheel or a disc, consider the prices you can get a RENN disc for.
Thanks. I currently have 404’s but have been offered use of a friend’s 900 disc. Not sure if I want to go through the hassle of swapping cassettes and stressing about ruining someone else’s wheel if there is no advantage to be gained.
In general the disc will be faster. Factors such as wind will play a major part. A disc can have a sail effect at certain wind angles. I’d say give it a shot. It takes about 20 seconds to swap a cassette and in a Tri or TT the chances of destroying or damaging a wheel are greatly diminished. Plus, having a disc is just extra cool points.
I ride a road bike, and I use a Hed3 front and disc rear. I raced Saturday with that set up without aerobars. I had a pair of Vision Tech shorties on my bike, but those things are horrendous. I can’t stay down in the bars for very long, so I just decided to take them off. I didn’t have time to get another pair, so I just raced with regular drop bars. I don’t see a problem with racing with a disc and a road bike. 99 percent of the time, a disc is faster, no matter what kind of bike it’s on.
RP
Which race are you considering using it for?
It was mostly a hypothetical question, but since it was offered I was thinking of borrowing it for IronMan Brazil… which is still a long way off.
Most of the stuff i’ve been reading on wheels is that there is very little to be gained on the average…i’m not talking perfect wind conditions etc…just your everyday type of racing…besides most discs or high end aero wheels won’t stand up to repeated high speed braking like on a road course …
Considering that the bike is causing the least aero drag of the set up you would be better off with, for example…a skin suit or an aero helmet or dropping a pound or two…
Mike Hutchinson one of the fastest TT riders today said it best…“A world championship has never been won by the choice of a wheel”…
Most of the stuff i’ve been reading on wheels is that there is very little to be gained on the average
It depends on what you consider ‘very little’. In the TT’s I do a disk is often worth the difference between 1st and 3rd.
Considering that the bike is causing the least aero drag of the set up you would be better off with, for example…a skin suit or an aero helmet or dropping a pound or two…
A disk will save much more than all the things you mentioned combined.
Scott Martin
Remember folks…this is not a TT bike but a road bike…having a better aero position would be much faster than a disc in this case…
I am also not saying it wouldn’t be the difference between 1 or 3rd place , but if your bringing a sword to a gun fight your already at a disadvantage…
I i beg to differ about the disk being the most important…if you read the suggestions by the current world champion Micheal Rogers his view is the fork and handlebars are the most important aerodynamic pieces that should be on a bike…
And a direct quote form Hutchinson on disc wheels " These are all marginal gains…You look at the internet message boards and they’re full of people who have bought a new disc wheel and can’t understand why there not going a minute per 25 miles faster"
FWIW… I am on a Felt F35R with Oval R900 fork and drop bars with Oval Clip-ons. My position was dialed in at a FIST certified shop. I hadn’t even considered getting a disc until I upgraded to a full on Tri-bike but having access to one for my second IM this spring got me to thinking:
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I didnt know if the benefits of having a disc appliled if you had all sorts of drag from a fat, round down tube and seat tube.
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I had not seen a disc on a road bike and did not want to become the velo-equivalent of the guy who rides around in a front wheel drive hyundai with a monster wing stapled to the back
I have no illusions about getting third, never mind first… but if it meant the difference between breaking 11 or not, I would do it.
Remember folks…this is not a TT bike but a road bike…having a better aero position would be much faster than a disc in this case…
I am also not saying it wouldn’t be the difference between 1 or 3rd place , but if your bringing a sword to a gun fight your already at a disadvantage…
I agree that a more aerodynamic position (which a TT/Tri bike may or may not afford depending on how it is set up) would provide a bigger benefit. But that wasn’t the question. The question was if a disk would make a difference when used with a road bike. If the question was: “which would be faster, a road biek with a disk, or a well fitted, well positoned TT/Tri bike”, I’d agree wholeheartedly. A disk provides a fixed aerodynamic benefit, regardless of bike type or position. Any bike, with any rider, in any position will be faster with a disk than without.
I i beg to differ about the disk being the most important…if you read the suggestions by the current world champion Micheal Rogers his view is the fork and handlebars are the most important aerodynamic pieces that should be on a bike…
I might agree with the handlebars in so much as it might allow a more aerodynamic position. But as pieces of equipment alone, a disk provides more aerodynamic benefit (of course it depends on what you are comparing…a disk compared to a Zipp 808 wouldn’t help as much as say a full aero fork compared to an old, round steel fork). And while fork have been shown to be a pretty significant upgrade (since they touch undisturbed air), handlebars are more complicated as the rider is draped accross them is some fasion or another(in other words the relative difference between different aero bars is smaller than is suggested by wind tunnel testing them without a rider).
And a direct quote form Hutchinson on disc wheels " These are all marginal gains…You look at the internet message boards and they’re full of people who have bought a new disc wheel and can’t understand why there not going a minute per 25 miles faster"
Well, again, it depends on what you are replacing when using the disk. The fact is a disk will always be faster, no matter what (though Zipp’s data shows their new 808 slightly outperforms a disk at some wind angles). The amount of time you save with a disk depends on wind direction, wind speed, and how fast you’re going (the slower you go, the more time a disk will save!).
Scott Martin
Most of the stuff i’ve been reading on wheels is that there is very little to be gained on the average…i’m not talking perfect wind conditions etc…just your everyday type of racing…besides most discs or high end aero wheels won’t stand up to repeated high speed braking like on a road course …
Considering that the bike is causing the least aero drag of the set up you would be better off with, for example…a skin suit or an aero helmet or dropping a pound or two…
Mike Hutchinson one of the fastest TT riders today said it best…“A world championship has never been won by the choice of a
wheel”…
anyone who rides a world championship TT is using a disc and a deep rim front. no world championship has been won by using, say, a Zipp disc over a Campy disc. however, Levi beat Ullrich by 31 seconds. if Levi used a set of 32-spoke wheels in the time trial, he’d have lost (well, probably).
and a skin suit will not save you as much time as a disc. yes, the rider causes the most drag, but skin suits don’t reduce drag that much. the loss of a few pounds of excess weight, of course, will help more than just about any equipment.
and a skin suit will not save you as much time as a disc. yes, the rider causes the most drag, but skin suits don’t reduce drag that much. the loss of a few pounds of excess weight, of course, will help more than just about any equipment.
The loss of a few pounds of excess weight will do very little. Unless it’s a hillclimb, a few pounds dropped will do diddly actually. The difference of a 180 lb bike/rider and 190 lb bike/rider with the same power might amount to a second or two over 40k. A skin suit or aero helmet will save you at least an order of magnitude more. Wheels - 2 orders of magnitude.
well, lose a couple pounds and you’ll probably gain a lot of fitness.
well, lose a couple pounds and you’ll probably gain a lot of fitness.
Depends on what you define as “a couple pounds.” I’ve been stuck at 148-150 lbs for quite awhile. If I drop down to 144 (my target), I won’t be gaining any fitness. The fitness is already there.
Now if you are at 250 lbs and your ideal weight is 160-170, then yes, I agree that you’d gain a lot of fitness. But that’s not a drop of a couple pounds.
I’d say not worth the hassle. Difference would be pretty small, particularly at 20 mph (404 is pretty good). That said I use a 900 and it sounds and looks pretty cool.
John Cobb used to have a website that would calculate time differences for different wheels at different distance/condition/speed based on wind tunnel data. Seem to remember difference between 404 and disk was maybe 20 sec over 40K at 40 kph but could remember wrong.
Difference would be pretty small, particularly at 20 mph
The slower a rider is, the more benefit they gain from any aero advantage due to being on the course longer.
Any watts you save on the bike you can use for the run. Use the disk.
my tests of a Hed Jet deep vs. a CH Aero cover, on a Trek 2500 (1999) show minimal difference over 15-25miles. So far I would hesitate to say the difference is even statistically significant. On the other hand, every trial I’ve done the disk time is faster, if only by 15-30sec.
For an IM ride, you have a lot of time to accrue benefits, if the disk is even marginally better than the deep rim. I’d go with the disk…