What’s faster DISC or 88mm

Equipment
1

Hi people I Have a quick question,
I have a national 25km TT coming up in 1 month, going through bike setup, have a question…

I have access to a disc and 88mm wheel.

Disc is an older zipp with used conti competition TUB
88mm is a generic rim shape with ceramic bearings, latex tubes and s-works cotton clincher tyres . I ride this wheel day to day for training also

The course is undulating, and has 9 significant Turns
Any thoughts on what would be faster
Have no idea of my CDA or anything like that, just thought the TR forum might be able to help …

Thanks in advance

2

Generally the disc will be faster

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3

I believe rule of thumb is if you’re averaging over 27mph then disc is faster otherwise deep dish will be… I’m pretty sure I heard this on an older podcast not sure… I feel like @Nate_Pearson would know

4

That’s what enve told us, although other manufacturers say a disc is always faster:

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5

FYI dish relates to the wheel being centered on the axle not the depth of the cross section.

6

I meant deep section/rim was just a bit of slang… but thank you :+1:

7

The difference between a disc and a deep section isn’t as great as that between different skinsuits, helmets and of course your position. Get the latter three correct and the wheel difference will be marginal in comparison.

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8

Thanks everyone, my ski suit, helmet and position are all at the best possible point they can be
I’ve found the best balance of power out out and speed I think.
Appreciate all the input, I think I’ll just run my 88 as it will give me more price of mind as I ride it regularly

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9

Just throwing it out there, but NOTHING is faster than the sound of a disc wheel. The sound alone must add about 30 watts to ones ego :stuck_out_tongue:

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10

The aero expert in the newest FLO Cycling Podcast episode (#24) says: disc wheel. I’ve heard this opinion more times than I can count. The disc can even create a net negative drag (i.e. propel you forward) when the wind speed and direction is right.

Unless of course it’s an uphill TT, or a super duper windy course with violent gusts, Kona-style.

11

Easiest way to save watts and go faster… just look faster :call_me_hand:t3::call_me_hand:t3::stuck_out_tongue_winking_eye:

Err. Red velotoze shoe covers and rule 28 black socks

I didn’t know if this was supposed to be a pun or not (“price of mind”) but the point is you know you’ve got all the relatively low hanging fruit (skin suit etc.)… if u have access to the disc maybe find a stretch of road and do couple 5-10min efforts in both set ups and then plug into BestBikeSplit aero analyzer to compare cda.

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12

Aerodynamically, the disc is the faster option in most setups . However, the tyres are an issue. Continental tubular, that’s with a butyl inner tube? I can’t speak for the rolling resistance och the conti tyre itself, but I would guess that the turbo cotton w. latex tube rolls faster than the conti tubular by a few watts. In this case, I would go with the clincher wheel.

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