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Home > Forum > Triathlon Forum > Geeky Rear Wheel Question? Deep v Disc

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Geeky Rear Wheel Question? Deep v Disc
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Jwwilkins
Mar 2, 21 2:52
Post #1 of 10 (942 views)
Hi Ladies and Gents,

Currently I'm training for a full Ironman an have intentions of doing the bike spit in around 4:45/5:00 based on the course I'm racing at.

I run a Enve 95mm rear wheel, but I am contemplating getting a rear disc wheel. As I already have a deep rim does anyone know if the Disc Wheel will reduce much drag in comparison to the 95mm wheel therefore saving watts and saving my legs for the run which is my worst discipline of the three. The course I'm doing which is IM Finland the ride is lined by trees majority of the time so there should be no/not much cross wind.

I am running a Cervelo P5 TT bike with Di2's, Qring crank, I have had a bike fit and own an aero helmet. This is so you have some concept, before someone says just buy an aero helmet.

I'm just wondering the difference between 95mm and Disc? If anyone has some interesting stats or some analytics I love looking into that stuff.

Thanks
James
Last edited by: Jwwilkins: Mar 2, 21 3:17
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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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SBRcanuck
Mar 2, 21 4:58
Post #2 of 10 (899 views)
Based on Flo's data here:
https://flocycling.com/pages/aerodynamics

You -might- save about 30 seconds? Of course lots of other factors involved - speed you are traveling, tire selection and pressure, etc.

If you've spent much time on this forum, you already know a disc is pretty much always faster, just hard to tell how much.
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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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rcmioga
Mar 2, 21 5:22
Post #3 of 10 (876 views)
One thing that might be counter intuitive is that a disc rear wheel generally doesn't make you less stable in cross winds--the bigger issue is the front wheel. There are some rear discs in cross-winds that actually provide forward force (much like the keel in a sail boat)....Deep rear wheels can do much the same, just not as much....

They are expensive and of limited use beyond racing.

I have always used them (except in Hawaii of course) but it's more of a mental thing--I want to take advantage of every advantage and I'm willing to pay the $s for it because I value my time (training investment) more than my $s....
Randy Christofferson(http://www.rcmioga.blogspot.com

Insert Doubt. Erase Hope. Crush Dreams.
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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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desert dude
Mar 2, 21 6:34
Post #4 of 10 (843 views)
This topic has been coming up a lot recently. Several great threads on it if you search back even to just the beginning of February.

Since this has come up so much start here. Then if you feel the desire to read further just search. Lots of good thoughts in those threads.

Finally if you really want to see the difference in watts and time savings hit me up for some aero testing. Plus we'll sort out that helmet and kit while you're there.
Brian Stover USAT LII
Accelerate3 Coaching
Insta

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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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Rideon77
Mar 2, 21 6:44
Post #5 of 10 (833 views)
Jwwilkins wrote:
Hi Ladies and Gents,

Currently I'm training for a full Ironman an have intentions of doing the bike spit in around 4:45/5:00 based on the course I'm racing at.

I run a Enve 95mm rear wheel, but I am contemplating getting a rear disc wheel. As I already have a deep rim does anyone know if the Disc Wheel will reduce much drag in comparison to the 95mm wheel therefore saving watts and saving my legs for the run which is my worst discipline of the three. The course I'm doing which is IM Finland the ride is lined by trees majority of the time so there should be no/not much cross wind.

I am running a Cervelo P5 TT bike with Di2's, Qring crank, I have had a bike fit and own an aero helmet. This is so you have some concept, before someone says just buy an aero helmet.

I'm just wondering the difference between 95mm and Disc? If anyone has some interesting stats or some analytics I love looking into that stuff.

Thanks
James


95 is pretty deep. A disk is always faster but the question is "how much faster" compared to your 95? The answer is not much compared to the cost assuming you don't own the disc already.

Aero really doesn't care about that your drive train is Di2 or that you run a Qring crank.

Aero does care about your fit, your helmet, and your kit that you plan on wearing. Which, if improved from your current baseline, will make a bigger difference vs a 95/disc decision.
Last edited by: Rideon77: Mar 2, 21 6:45
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Re: Geeky Rear Wheel Question? Deep v Disc [SBRcanuck] [ In reply to ]
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Jwwilkins
Mar 2, 21 8:33
Post #6 of 10 (800 views)
Thanks - hadn't come across this brand before. Some relay interesting content.
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Re: Geeky Rear Wheel Question? Deep v Disc [desert dude] [ In reply to ]
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Jwwilkins
Mar 2, 21 9:00
Post #7 of 10 (786 views)
Thank you so much for the link to the other forum.... really interesting content and very valuable in my decision.
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Re: Geeky Rear Wheel Question? Deep v Disc [Rideon77] [ In reply to ]
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Jwwilkins
Mar 2, 21 9:03
Post #8 of 10 (783 views)
I know aero doesn't care about the gears or drivetrain, but I do know that a couple of people might comment saying spend the money on a better bike or aero helmet or new gears... so was trying to pre-empt that.
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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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Rideon77
Mar 2, 21 12:44
Post #9 of 10 (724 views)
Jwwilkins wrote:
I know aero doesn't care about the gears or drivetrain, but I do know that a couple of people might comment saying spend the money on a better bike or aero helmet or new gears... so was trying to pre-empt that.

Gotcha. Your kit/suit makes a huge difference.
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Re: Geeky Rear Wheel Question? Deep v Disc [Jwwilkins] [ In reply to ]
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Titanflexr
Mar 2, 21 14:37
Post #10 of 10 (696 views)
As mentioned, the disc is marginally faster (ride a disc for any race that allows it and doesn't contain the word Huez). If you already have the deep rear wheel, the question is really if you want to spend for a disc to get that last 30sec. Certainly in the aero hierarchy there are things to spend on first....but if you have done all that and have the desire/means....
ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)
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