Wheels for my TT bike

Hello everyone. I have just bought my first TT bike. I am looking for advice on wheels depth. I am 164 cm tall and 55kg. What depth of the wheels would be good for me? My biggest concern is the wind. I live in Ireland so it is windy almost every time the TT competition is on. I would say, what would be the best up to wind blowing 35km/h (if it is more I will just not take part). I was thinking about 85mm (or disk - would it be a big difference?) back wheel and 60mm front wheel. At the moment in my road bike I have 45mm front and back and I need to admit that front wheel is managable but most of the time I would prefer to have something lower at the front. I wrote 60mm front because I assume that in TT position front wheel is better pushed down than on the ordinary road bike (but I may be wrong of course). Thank you in advance for all your comments.

The question is… How deep are your pockets?

There is a saying when modifying cars

“Tell me how much you have and I’ll tell you how fast can you go”. This apply to cycling as well…(sadly)…

Anyway… For windy I would get something like 65 for the back and 45 to 50 in the front… Is a good combination of you don’t want to go full disc in the back

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A rear disc or deep wheel is not unstable in the wind. The front whee is what is impacted by the wind.

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I mean… Not totally true…

If you get cross winds the wind will get trap on the wheel and if the week happen to be a disc it will act like a sail…

That said, The deeper the wheel, the more unstable it will be with cross winds.

Now, the front is where you can see big problem if you go too deep and get into strong cross winds…

@pawcyb15954 as you may or may not know, not all 60mm or 80mm etc…rims perform the same with respect to cross wind stability. I’ve experienced 80mm front rims handle way more cross wind than a competitors 50mm. You can probably do a little research and see the same brands bubble to the top as far as stability is concerned. Unfortunately, those wheel sets seem to be on the more expensive end of the spectrum. I do think paying top dollar for wheels is worth it. Test, test, test if possible. Take your time buying…

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You’re right that there is more weight on the front wheel of a TT bike. Even more for a triathlon or non-UCI TT setup. This weight downwards on the front wheel doesn’t stabilize it. In fact, it probably makes it feel less stable.

The thing that stabilizes a deep front wheel during gusty crosswinds is your ability to apply a bit of forward pressure on the bars.

Riding 80mm depth wheel on a road bike is easier than 80mm depth on a TT bike for this reason.

I’m 94kg and ride 80mm front and disc rear (if my wife isn’t using the disc) no matter the conditions.
My wife is 63kg and rides 80mm front and disc rear, no matter the conditions. Occasionally I’ll encourage her to run a shallower front if it’s really gnarly out and performance isn’t mission-critical. It’s a hard sell. It is slower.

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For the rear, always a rear disc unless it’s not allowed in an event (e.g. Kona) or has an insane amount of climbing and technical descending (like Alpe d/Huez triathlon, or savageman in the states).

Front, I would actually go against the grain and recommend a mid-depth (50-60mm). Yes you may be giving up a few seconds in a 40k vs 80mm+, but in windy conditions, you’ll gain that back by not having to make as many corrections due to wind. If you’re events have any hills, mid depth from wheels are often 100g lighter than deeper wheels (not a ton but not nothing either).

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To echo everyone else, it really depends on your budget. My thought is if you can afford it, buy two front wheels: as fast and deep as you’re comfortable with (80-100mm or trispoke), and a mid-depth (50-60) for windy days. For the rear, always disc as long as it’s allowed.

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I am a relative light weight at 57-59kg and 175cm tall but I’d always use my disc. When the winds are over 50kph I’ve swapped out my 62.5 mm Hadron front wheel for my 35mm aluminium Hunt wheel. At 35kph I’d still be riding the 62.5mm deep front wheel though and just be wary of gaps in hedges etc

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Two ways to go…

Way the First: Disk wheel on the back tri-spoke on the front. This used to be the go-to setup but it’s fallen out of favor for the…

Way the Second: Disk wheel on the back & 60mm+ on the front.

If the wind is sketchy swap out the front wheel for a training wheel…you’ll still get substantial aerodynamic benefit from the rear disk wheel. You may not believe it (I didn’t) but having a disk on the back doesn’t impact handling that much in windy conditions.

I like the tri spoke/disk combo but I’ve never had the chance to test a 60mm/disk combo.

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BTW if you just want to try a disk on the back you can get a wheel cover for about 100 bones…a very, very good dollars per watt investment.

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For sure a disc on the rear - a decent cross wind will turn it into a sail and push you along (well, kinda…). It pushes the centre of pressure rearward (because the wind is blowing on a large surface area at the back of the bike) which makes the front more stable. As above, disc covers are a great budget option.

I’d go for around 50-60mm in the front - you might be a tad faster with a deeper rim but the key is getting the tyre width to match the rim. A well-matched 50mm rim and tyre is more than likely faster and will handle better than a badly-matched 80mm rim and tyre. Wider U-section rims seem to have the edge over narrower or V-section rims, because they cope with cross-winds better. Also using a super-fast tyre and latex tubes can save you more than you’ll gain with a deeper rim.

It always makes me laugh when people choose not to use a rear disc wheel in the wind. Didn’t realise their bikes were that kind of “rear wheel drive” (I know RWD doesn’t mean the rear axle has steering components…)

What wheel covers do people recommend? I’d like to try one before I drop £1k on a real rear disk.

I’ve settled on wheelbuilder.com aerojacket. Seems like just about any wheel…they know exactly what size to cut the aerojacket. Plus, if you’re supporting some Jr riders that might be on 650 wheels aerojacket has ‘got you covered’ no prob.

https://wheelbuilder.com/aerojacket-disc-covers/

FLO cycling just blogged about disk wheels vs wheel covers, btw. So, some timely info from somebody who is in the industry.

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