Aero wheels for a small light rider

Well that was an entertaining
Well that was an entertaining read.

Being (as many people will be) an owner of 3cross 32 hand built wheels and 20/24 deep section alloy rim aero wheels (and indeed of many more wheels) I can state my *opinion* based on owning both sets for four years and *seat of the pants* and also a bit of *garminology* that the aero wheels are, not surprisingly, faster and that the 32 hand-builts feel more stable and more comfortable (not a contradiction – more spokes, round spokes and more crossing). They wheels sets cost within £20 of each other and were around £250 from memory.

The OP would certainly be better off with the aero wheels given their weight and intention. And guess what, I *change my wheels* depending on what I am about to do. I have training wheels and fast wheels. I don;t race so the fast wheels are *just for fun*. Cycling is a joy, I am allowed to indulge it in anyway I like. I have fun riding and buying and tinkering with bikes. It’s not an equation.

While I share a little of the cynicism above and am a bit of a scrooge myself (I mostly buy second hand) if I did race I would certainly consider a set of carbon rims in the aero format… but only if I were Cat2 or above 😉 Otherwise it’s much more useful having two sets of wheels which are ‘good enough’ at their respective jobs.

Also worth noting that open pros have pretty much had their day, they are a good cheap training rim but not a patch on the newer wider rims from Velocity (Pacenti and so on, but I don’t have those). I base this *opinion* on having ridden both, one after the other on the same hubs with the same lacing pattern and the same tyres.

Finally would recommend a good read of the DCR website as there is a lot of pretty well balanced commentary in there on relative strengths and weaknesses of materials etc.

Sorry, how rude of me, you
Sorry, how rude of me, you asked for a response on some ‘facts’ and I assume from an ‘engineering’ point of view.

1 aero wheels are weak: there is no inherent reason why this should be the case. Wheels with a lower spoke count will be less robust all other things being equal, however all other things are not equal. Deeper sections will have higher Section modulus and therefore resist bending better than shallow sections. The material is likely to have a higher tensile strength as carbon is normally used in preference to aluminium, although it may be more brittle. But more importantly, in the world of engineering we are normally trying to optimise conflicting requirements. The OP weighs 7.5 stone and proposes to use them for triathlon races. This suggests that strength is not the overwhelming priority for the intended use, so ‘strong enough’ should be well within the capability of well made aero wheels.
2 aero wheels are not very aero in most conditions: there’s pretty good evidence that they are more aero most of the time than box section rims, so I assume what you’re getting at here is that they’re not aero enough for enough of the time? I think that’s up to the purchaser but again looking at the intended use, triathlon, drafting is illegal, courses are usually not mountainous and the handling issues are limited because there is no bunch racing so if there is a situation where the benefits are most likely to be realised this is probably it.
3 they’re expensive: my first suggestion costs £400, roughly the same as your hand built open pro example. And there are non aero options up to the £1k limit given. So no, not necessarily. You can go cheaper than that if you’re willing to compromise on weight but given the budget available, there seemed no reason to. They certainly can be expensive like most things but it’s not a given.
In an engineering sense I think where you went wrong was to ignore the brief. It’s a tendency we engineers have to be vigilant against.

Martyn_K writes:

No, what i

Martyn_K writes:

No, what i meant was exactly what i wrote.

“They even climb very well in comparison to a set of lighter, low profile rims i also own.”

I know what you wrote. The clear implication was that they were better for
climbing.

At no point in my post did i imply that the Cero RC45 wheels i bought made
me a faster, better rider.

Good. Because they don’t.

I don’t think i should have to justify my purchase but because of the
tone of your previous posts i’ll play the game a little.

This isn’t some “game”. People come on this forum for information. As for your
assertion that you shouldn’t justify your (expensive) purchase, you should.
Readers want to know the pros and cons of products that poster’s have bought.

I like the look of carbon deep sections.

Translation: I’m a fashion victim.

For other general riding or fast flat rides i use the carbon deep sections.

Wouldn’t it be more economical to use cheaper wheels (ie. Al alloy rims)
for general riding?

If you trash your wheel in a pothole, you can just get another (cheap)
rim and/or spokes and rebuild the wheel.

Or do you like to “show-off” your expensive wheels irrespective of their
suitability?

I’ve spent some time this
I’ve spent some time this year riding a variety of bikes from Giant (I work at a Giant brand store) including the Defy Advanced (disc), TCR (race) and Propel (aero race).

I’ve used 2 different Propel, the mid range with the carbon/aluminum deep sections, and the bike below with the full carbon wheel. I’ve also experimented using low profile aluminium wheels from the TCR in the same bikes, when its been very wet / windy.

I don’t claim to be an expert, I don’t race. I do like riding fast whether its climbing hills, descending hills or on the flat – I have Regent’s Park less than 1km from my house in NW London which is ideal for fast flat sessions.

The aero wheels are very noticeable in terms of straight line speed, and maintaining a high speed once moving. Once moving fast, the wheels make a cool humming noise!

Acceleration is slower than the low profile wheels, obviously.

The full carbon wheel accelerates faster than the carbon / aluminium wheels, as the lighter weight (approx 200 gm) than the carbon / aluminium wheel is very noticeable. It also feels stiffer in terms of side to side flex. All the wheels have DT Swiss 240 internals so similar pick up.

The carbon / aluminium is much better behaved in wet weather as it has a regular aluminium brake track; the full carbon wheel works much better braking in the dry. Both aero wheelsets can be a handful in blustery conditions, but you get used to maintaining a firm grip on the bars!

If you are getting aero wheels, I’d look carefully at spending a decent amount to get a quality wheel set, and research the support you will get from the distributor in terms of spare parts and repair; as this makes ‘ownership’ of your wheelset much less painful.

freebsd_frank wrote:

freebsd_frank wrote:

Martyn_K writes:

They even climb very well in comparison to a set of lighter, low profile rims i also own.

Do you mean they climb better than the lighter, low profile rims?

I hope not. Because that would mean your fancy, heavier deep section rims defy physics.

Truly remarkable what you can buy for “just” £800….. 😉

No, what i meant was exactly what i wrote.

“They even climb very well in comparison to a set of lighter, low profile rims i also own.”

At no point in my post did i imply that the Cero RC45 wheels i bought made me a faster, better rider. I only confirmed that i too had been researching the minefield that is deep section wheels, noted what i eventually bought and gave some feedback as to the performance of them.

I don’t think i should have to justify my purchase but because of the tone of your previous posts i’ll play the game a little.

I had some money to spend after an annual bonus from work. I just so happened to already own 2 pairs of alu rimmed low profile wheels so i did not see the point in having yet another pair. I like the look of carbon deep sections. I fancied buying some, so i did. I now use the low profile rims for long days in the hills/ mountains when i will get the benefit of them. For other general riding or fast flat rides i use the carbon deep sections.

For the record i am 5’10” and 68kgs, have so far covered 4500 miles this year at an average speed of over 19mph in a mix of club rides and solo. So i don’t think that losing lots of weight or training a great deal harder will make a major difference.

Also, again please excuse my

Also, again please excuse my lack of knowledge but why would you not want to use carbon clinches on long alpine descents?

I think he’s referring to carbon clincher rims.

They heat up and can fail:

http://www.bikeradar.com/gear/article/are-carbon-fiber-clinchers-safe-34521/

In that article, there is a lot of hand-waving by the Reynolds spokesman:

Aguero said Reynolds’ heat failure rate is “less than 1 percent.”

Yeah, but what he doesn’t mention is that probably <1% who buy their wheels go down Alpine passes with them ie. a 100% failure rate.

You might also want to look at:
http://www.wheelbuilder.com/faq.php?q_id=10

Aluminum braking surfaces generally stop in all weather conditions and do not require special brake pads. Carbon braking surfaces require special brake pads, do not stop as well in wet weather, and are more sensitive to overheating under heavy braking conditions.

I forgot about them being crap in the wet in my original post

This though from the same FAQ, sums it up:

Beauty is in the eye of the… , however we all agree those carbon wheels look cool on your bike.

Translation: they’re an expensive fashion accessory.

Don’t believe the bogus wind-tunnel testing. In most conditions they are not
going to make you go any faster. Even in ideal conditions, on a straight
course with no hills or cross-winds, the gains are marginal in the grand
scheme of things.

I’m sorry, you’re just going to have to train harder and for that you need a
robust set of wheels. When training it doesn’t matter a damn how heavy or
non-aero your wheels are. In fact, it’s an advantage (more resistance).