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The one million and first post on disc vs. non-disc rear wheel
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While the title is stated in sarcasm, I'm sincerely interested in opinions here...

Currently riding a combination of Bontrager Aeolus 7/9 TLR's, tubeless, with Schawlbe Pro 1's. Was considering a FLO disc for IMFL 2018, but when looking at their site, I noticed the difference between their 90 carbon clincher (4:48 benefit at IM distance) and their disc (5:19 at IM distance) is 31 seconds. I see a legitimate argument for purchasing the disc if someone was coming from a standard-ish rear wheel, but not so much from where I am at currently.

I guess the question is less around whether or not to buy the disc, but more around the analysis provided on the site. If in general, the difference between a 90 depth wheel and a disc is that small, I see no value in the purchase. 31 seconds for a FMOP/MOP guy in his middle 40's isn't worth ~$1,000.00. If people think the difference is greater, like upwards of a few minutes, please let know...

Thanks!
-Mike
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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I agree with your analysis, which I think it is more important for MOP folks (me included) to buy what they think looks the best on their bikes! :)
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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Read this
http://forum.slowtwitch.com/..._triathlon_P6391715/
and substitute "flo" for "ENVE".
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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Go to wheel builder and buy a cover to tape to your rear wheel. 30 seconds is worth $100
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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I could be mistaken but I do not believe Flo's data takes into account rotational drag (watts to spin). Their study is just takes translational drag into consideration. There will be additional savings with a disc that isn't accounted for.

Flo can correct me if I'm wrong though.

That all said, if you want a disc wheel, buy one. If you feel you don't need one, then don't buy one. It's a personal choice. At the end of the day, all that matters if you are happy and having fun.

blog
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Re: The one million and first post on disc vs. non-disc rear wheel [rjrankin] [ In reply to ]
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rjrankin wrote:
Go to wheel builder and buy a cover to tape to your rear wheel. 30 seconds is worth $100

I always thought this was dumb. If you're going to use a wheel cover, you may as well use a super shallow climbing wheel with it. No point in running a heavy deep wheel if you're going to use a wheel cover.
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Re: The one million and first post on disc vs. non-disc rear wheel [jmjtri] [ In reply to ]
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jmjtri wrote:
rjrankin wrote:
Go to wheel builder and buy a cover to tape to your rear wheel. 30 seconds is worth $100


I always thought this was dumb. If you're going to use a wheel cover, you may as well use a super shallow climbing wheel with it. No point in running a heavy deep wheel if you're going to use a wheel cover.

If you already have a deep wheel is it not more aerodynamic to cover it? Serious question.
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Re: The one million and first post on disc vs. non-disc rear wheel [rjrankin] [ In reply to ]
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rjrankin wrote:
jmjtri wrote:
rjrankin wrote:
Go to wheel builder and buy a cover to tape to your rear wheel. 30 seconds is worth $100


I always thought this was dumb. If you're going to use a wheel cover, you may as well use a super shallow climbing wheel with it. No point in running a heavy deep wheel if you're going to use a wheel cover.


If you already have a deep wheel is it not more aerodynamic to cover it? Serious question.

Yes, but as the OP said about Flo's data, the diff between a deep wheel vs a disc ( or cover) is pretty minimal.
I had a wheelbuilder disc cover a while ago, I hated it. I thought it looked cheap. I didn't like have a plastic covered wheel on a bike I spent 6k on. Just spend $400 on a used HED Jet disc if you want a disc and don't want to break the bank.
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Re: The one million and first post on disc vs. non-disc rear wheel [SBRcanuck] [ In reply to ]
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SBRcanuck wrote:
rjrankin wrote:
jmjtri wrote:
rjrankin wrote:
Go to wheel builder and buy a cover to tape to your rear wheel. 30 seconds is worth $100


I always thought this was dumb. If you're going to use a wheel cover, you may as well use a super shallow climbing wheel with it. No point in running a heavy deep wheel if you're going to use a wheel cover.


If you already have a deep wheel is it not more aerodynamic to cover it? Serious question.


Yes, but as the OP said about Flo's data, the diff between a deep wheel vs a disc ( or cover) is pretty minimal.
I had a wheelbuilder disc cover a while ago, I hated it. I thought it looked cheap. I didn't like have a plastic covered wheel on a bike I spent 6k on. Just spend $400 on a used HED Jet disc if you want a disc and don't want to break the bank.

I get that. Was just offering a suggestion to get those 30 seconds while spending 1/10th the cost.

The person I quoted made it seem like it's a wash. I understand that a shallower covered wheel would be lighter, but is there no benefit to covering the OP's current wheel?
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Re: The one million and first post on disc vs. non-disc rear wheel [stevej] [ In reply to ]
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stevej wrote:
I could be mistaken but I do not believe Flo's data takes into account rotational drag (watts to spin). Their study is just takes translational drag into consideration. There will be additional savings with a disc that isn't accounted for.

Flo can correct me if I'm wrong though.

That all said, if you want a disc wheel, buy one. If you feel you don't need one, then don't buy one. It's a personal choice. At the end of the day, all that matters if you are happy and having fun.

+1. Rotational drag is hard to pin down. There are some pretty different/conflicting estimates of the overall magnitude. There are different protocols as well as the validity of individual wheel vs on bike estimates, bike+rider...

The good news is that only 1 test seems to have shown a deep wheel being faster and that was using an ENVE 9 on a Canyon Speedmax with no watts-to-spin adjustment. Whether you save 3 watts or 10 watts will depend on a ton of variables, but a disc will almost certainly be faster, which is what really matters.
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Re: The one million and first post on disc vs. non-disc rear wheel [rjrankin] [ In reply to ]
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rjrankin wrote:

The person I quoted made it seem like it's a wash. I understand that a shallower covered wheel would be lighter, but is there no benefit to covering the OP's current wheel?


There absolutely is.

Over all the years I've tested (you can see my ST posts going back 13 years), I've never found anything faster than a "bump disk" -- that is a deep ovoid wheel (Zipp 808, etc) with a disk cover. Believe me, I've tested a dozen or so different disks.

There's a reason Hed makes their Jet disks in that shape and that Zipp created the Sub 9 after denying for a long time that "bump disks" were better.

If you poke around the wheelbuilder site, I think you can find a wind tunnel test that pretty much confirms my extensive field testing. Keep the deep wheel and get a cover.

My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
Last edited by: jens: Aug 22, 17 1:31
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Re: The one million and first post on disc vs. non-disc rear wheel [jens] [ In reply to ]
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jens wrote:

There absolutely is.

Over all the years I've tested (you can see my ST posts going back 13 years), I've never found anything faster than a "bump disk" -- that is a deep ovoid wheel (Zipp 808, etc) with a disk cover. Believe me, I've tested a dozen or so different disks.

There's a reason Hed makes their Jet disks in that shape and that Zipp created the Sub 9 after denying for a long time that "bump disks" were better.

If you poke around the wheelbuilder site, I think you can find a wind tunnel test that pretty much confirms my extensive field testing. Keep the deep wheel and get a cover.

Thank you all for the feedback, much appreciated. I have to admit, I have historically been in the camp of wheel covers not being aesthetically pleasing (as someone said, they look cheap). With that said, and based on the bold text above, I'd have to believe my current rear wheel (Aeolus 9 TLR) falls into a similar category as an 808 so in theory, a disc cover would create this "bump disk" you are referring to?

Based on these comments, my existing wheel with a disc cover would be faster than a HED or FLO disc?

Thanks,
-Mike
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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MJGuswiler wrote:

...
Based on these comments, my existing wheel with a disc cover would be faster than a HED or FLO disc?

Thanks,
-Mike

I actually own a Hed disk because I do some UCI-sanctioned races, which prohibit disk covers.

The Hed tests very close to an 808 with a cover (to close to call), which is no surprise, since they have nearly the same shape. The Hed disk has more graceful transitions. But the 808+cover is somewhat more lenticular, which probably makes up for it. I can't speak for the Flo disk.

Say, I found the Wheelbuilder page:

http://www.wheelbuilder.com/aerodisc-data.html


This pretty much confirms my experience. The only thing I find surprising is that the low profile wheel with a cover actually outperforms at 20 degree yaw. But I doubt most riders experience yaw that high very often.









My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
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Re: The one million and first post on disc vs. non-disc rear wheel [jens] [ In reply to ]
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jens wrote:
The Hed tests very close to an 808 with a cover (to close to call), which is no surprise, since they have nearly the same shape. The Hed disk has more graceful transitions. But the 808+cover is somewhat more lenticular, which probably makes up for it. I can't speak for the Flo disk.

Stumbled on this thread and wanted to ask your opinion. I currently race with a rear FLO 90 but would like to pick up a disc between now and next season. I've been thinking I'd sell the 90 and pick up either a FLO Disc (alu+carbon disc is a great deal) or HED Jet Disc Plus (more expensive). But your comments/experience make me wonder if getting a disc cover for the 90 would be a better idea. Thoughts? Would a dedicated disc be that much better or are gains over the 90 pretty much the same whether an actual disc or a disc cover?

This assumes a disc cover will work with my Scott Plasma. Wheelbuilder lists the Scott as one of the incompatible bikes because of narrow chain stays, but I think that the 90 is deep enough that the disc cover won't extend out enough for the narrow part of the chain stays to be a problem.

Thanks!
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Re: The one million and first post on disc vs. non-disc rear wheel [Northy] [ In reply to ]
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Northy wrote:
This assumes a disc cover will work with my Scott Plasma. Wheelbuilder lists the Scott as one of the incompatible bikes because of narrow chain stays, but I think that the 90 is deep enough that the disc cover won't extend out enough for the narrow part of the chain stays to be a problem.

or, if you get a nice year end bonus:



which i think is the HED disc being discussed here. looks pretty good on a plasma!

Dan Empfield
aka Slowman
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Re: The one million and first post on disc vs. non-disc rear wheel [Slowman] [ In reply to ]
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Slowman wrote:
which i think is the HED disc being discussed here. looks pretty good on a plasma!

Does look pretty good. Would probably look even better if those HED decals were yellow. Or maybe you just wanted to match Sika's bar tape?
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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MJGuswiler wrote:
While the title is stated in sarcasm, I'm sincerely interested in opinions here...

Currently riding a combination of Bontrager Aeolus 7/9 TLR's, tubeless, with Schawlbe Pro 1's. Was considering a FLO disc for IMFL 2018, but when looking at their site, I noticed the difference between their 90 carbon clincher (4:48 benefit at IM distance) and their disc (5:19 at IM distance) is 31 seconds. I see a legitimate argument for purchasing the disc if someone was coming from a standard-ish rear wheel, but not so much from where I am at currently.

I guess the question is less around whether or not to buy the disc, but more around the analysis provided on the site. If in general, the difference between a 90 depth wheel and a disc is that small, I see no value in the purchase. 31 seconds for a FMOP/MOP guy in his middle 40's isn't worth ~$1,000.00. If people think the difference is greater, like upwards of a few minutes, please let know...

Thanks!
-Mike
I have a set of Hed Jet 6+'s with Schwalbe Pro1 tubeless and I just rode IMLP70.3 still used my HED 7 Stinger with a disc and Vittoria Speed G's tubulars. Im 40 something MOP (2:57 bike split at LP 6:02 overall) and goofy enough to buy cool bike parts just because I like cool bike parts. Personally I would probably buy the disc but I've been a gearhead a lot longer than Ive been a triathlete.

I know technically the HED S7/Disc is faster than the Jet 6+ but I doubt it is anything I will ever see or notice in a race. I think the difference between a disc and a 90mm wheel would be even smaller. I think it boils down to personal preference I buy all the cool little stuff for the bike but still haven't shaved my legs lol!
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Re: The one million and first post on disc vs. non-disc rear wheel [Northy] [ In reply to ]
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Northy wrote:
Slowman wrote:
which i think is the HED disc being discussed here. looks pretty good on a plasma!


Does look pretty good. Would probably look even better if those HED decals were yellow. Or maybe you just wanted to match Sika's bar tape?

if the bike matches it goes slower.

Dan Empfield
aka Slowman
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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MJGuswiler wrote:
While the title is stated in sarcasm, I'm sincerely interested in opinions here...

Currently riding a combination of Bontrager Aeolus 7/9 TLR's, tubeless, with Schawlbe Pro 1's. Was considering a FLO disc for IMFL 2018, but when looking at their site, I noticed the difference between their 90 carbon clincher (4:48 benefit at IM distance) and their disc (5:19 at IM distance) is 31 seconds. I see a legitimate argument for purchasing the disc if someone was coming from a standard-ish rear wheel, but not so much from where I am at currently.

I guess the question is less around whether or not to buy the disc, but more around the analysis provided on the site. If in general, the difference between a 90 depth wheel and a disc is that small, I see no value in the purchase. 31 seconds for a FMOP/MOP guy in his middle 40's isn't worth ~$1,000.00. If people think the difference is greater, like upwards of a few minutes, please let know...

Thanks!
-Mike

I suppose there are so many variables, I'm not sure how much credence you can give some of this data. I have a 30km abandoned road that I use to do TTs and FTP tests on to see how I'm going. It's also good for testing out new gear. Going from a rear 1080 to Reno disc I dropped my PB from 50mins to 48mins despite not being as fit as when I did the 50mins 3 months earlier. So equating to 4mins saving for a 90.3. Not exactly a scientific study, but I instantly felt the difference.

I think Wheelcovers are just as quick as most discs, but look pretty average.
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Re: The one million and first post on disc vs. non-disc rear wheel [MJGuswiler] [ In reply to ]
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I haven't read anyone else's posts. So if some else said it - cheers.

Pick a wheel and train like crazy. Aero data is great but it takes about a terabyte (probably more) for one angle and most companies just figure out a way to justify the mold they've created. So, train. Train and then when the aero differences discussed on slowtwitch seem like a lot, train some more.

So, a disc might save you 40 seconds, maybe even more depending on which site you visit, on a hypothetical course (where, of course, all things have to be equal and you can't have come out of the aero position for any of this to have any validity) but, ride your bike, mate.

Wheels are great. Bontrager makes a phenomenal wheel (personal experience). But, the best wheel is the one you crush day in and day out. Show up on race day having trained the Sh!% out of yourself and your set up and then post your question. My guess is, disc won't seem so important.

Counter argument to the training stance........................Mark Allen dropped a 4:46 on a Huffy
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Re: The one million and first post on disc vs. non-disc rear wheel [Northy] [ In reply to ]
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If you're going to get a Flo disc, just cover the 90. The Flo disc literally is just that anyway. The HED disc is the same, although I don't know that one for sure.
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Re: The one million and first post on disc vs. non-disc rear wheel [imswimmer328] [ In reply to ]
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A cover didn't test so well in Aerocoaches data for their new disc - http://www.aero-coach.co.uk/...ubeless-disc-wheel-1

Guessing though this was a cover on a shallow rim.
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Re: The one million and first post on disc vs. non-disc rear wheel [Slowman] [ In reply to ]
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Slowman wrote:
Northy wrote:
Slowman wrote:
which i think is the HED disc being discussed here. looks pretty good on a plasma!


Does look pretty good. Would probably look even better if those HED decals were yellow. Or maybe you just wanted to match Sika's bar tape?

if the bike matches it goes slower.

False. Wheels + frame + helmet matching = 6 watts saved.

:)
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Re: The one million and first post on disc vs. non-disc rear wheel [Northy] [ In reply to ]
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Northy wrote:


Would probably look even better if those HED decals were yellow.

You can get yellow HED decals here: http://www.ebay.com/...047675.c100005.m1851
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Re: The one million and first post on disc vs. non-disc rear wheel [boing] [ In reply to ]
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pretty cheap disk...sub 700 US
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