Time Trial or Triathlon Wheels

A number of friends have asked me at various times to make wheel recommendations or explain some of what I know about wheels.  I thought it was worth writing a little blog post to explain my perspective.  I'm only an "expert" from the standpoint that I've spent a significant amount of time researching and collecting what others have written, but that sort of collecting of information can still prove useful. So here goes...

First Things First

Apart from looking cool, the reason people buy high end wheels is to go faster.  It is worth noting that an expensive set of wheels may be one of the worst bangs-for-the-buck that you can do to get faster when doing individual events like a TT or triathlon bike leg.  It is a bit of a false dichotomy to say don't get race wheels until you do "X", because you can of course get race wheels and do "X" and get faster than just doing "X".  If you are resource constrained and want to know where to focus your time/energy/money first, other things make more sense.  You can Google various bang for the buck aerodynamic pages, but my rough breakdown is:

1. Position matters most: low, narrow and compact in front is generally going to be best (although not for everyone).  Having a good fitter and/or playing with your position with a camera available helps.
2. Clothes.  Even if you are in a skinsuit or trisuit, there can be a big difference between brands.
3. Fast tires (low Crr) and latex tubes.
4. Aero helmet.  Needs to fit well with your position.
5. Declutter: Don't have a million things hanging off your bike.  Hide your cabling.
6. Wheels: not great bang for the buck, but definitely helpful.  
7. Frame: not easily (or cheaply) changed, but modern super bikes can help drop some drag

"Free Speed"

Some people refer to things like race wheels as "free speed", which others may find ironic based on price tags of >$2500 for "free speed".  My perspective is that good up-front investment really does make these close to "free" compared to my primary cycling performance investment, my time.  In particular, a good set of wheels is a non-recurring effort investment that holds some of its value (resale) and pays off in a faster time in every race where I use them.  My training in contrast requires continual up keep and investment.  If I want to be 1 mph faster in a TT, I might need to invest an extra 2-4 hours a week training.  If I stop training for a little while, that investment goes away and I need to start over again.  In comparison, the wheels start to seem like a bargain and start to seem almost "free".  Of course, you don't need to spend $2500 for wheels to get a lot faster, there are some options that cost far below that and will get you 99% of the same benefit.

What Matters for Wheels

As far as a set of TT/Tri race wheels go, here is a pretty complete list of what properties about the wheels might matter to you when selecting wheels. 

1. Aerodynamics: How much drag do you save?
2. Handling: Is it scary in the wind?
3. Braking: Can I still stop on a dime?
4. Maintainability: Is changing the tire a pain?
5. Durability: Will they break when I go over a bump?
6. Tire choice: Can I find fast/cheap tires?
7. Cost/resale/availability: How much $, can I resell, can I actually find what I want?
8. Weight: For TT/Tri this doesn't matter, but lightweight gives some roadie cred.
9. Looks: Almost all look cool, some look super cool.

The thing that makes wheel selection a complex problem is that different people are going to weight the importance of each of the above factors differently and different wheels may meet different parts of those goals.   For example, lets look at a few different wheel design properties.

Wide vs. narrow

One of the recent trends in wheel design is wider "U-shaped" rims as opposed to older "V-shaped" narrow rims.  You can go read the marketing for Zipp's Firecrest design or Hed's SCT to see what the claimed advantages are, but they largely boil down to better handling and better aerodynamics with wider tires (e.g. Conti GP4000s 23mm).  From the consumer's perspective, the downside is that these are still the new hot thing and thus come at a cost premium.  The older designs are not much slower with the right tires and can be had at a significant bargain.

Deep vs. shallow

Deeper rim wheels, all other things equal, are faster.  Deeper rim wheels, all other things equal, are less stable and harder to handle in crosswinds.  There is also significantly diminishing returns as wheels get deeper.  The difference between a Hed6 and a Hed9 or a Zipp 404 and Zipp 808 are there, but they are quite small.  Ironically, it is often in higher yaw (e.g. higher crosswind) situations where the deeper wheels are faster, which are exactly the conditions in which they are more sketchy.  Whether this matters is very dependent on an individual rider and their comfort with different riding situations.  I found that my Hed trispokes were just fine for me in quite windy conditions even though they are known as pretty twitchy wheels.  One thing you can do to make this easier is to always use a deeper wheel in back (e.g. a disc) than front.  That may be counter-intuitive, but it actually provides more stable handling.  An Hed9+disc will be both faster and more stable than a pair of Hed9s.  A Hed6/9 will be more stable than a pair of Hed9s.  If you are on the more uncomfortable side, investing in the more recent "wide" rims discussed above may be worth the extra money.

Carbon vs. aluminum rim

This is one of those places that Zipp and Hed for example made different decisions.  Your main Zipp race wheels are structural carbon with carbon rims.  Hed's clincher offering is a carbon fairing over an aluminum rim (their tubular is all carbon).  The carbon has some advantages in terms of weight and perhaps bling (both of which we mentioned doesn't actually matter for TT/Tri), otherwise it is a bit annoying.  It requires special brake pads, so if you swap wheels you have to swap pads.  While manufacturers have worked hard on improving the braking for carbon rims, they still don't behave as nicely and reliably as aluminum.  I personally have ridden carbon rims (and plan to ride them on my road bike), so I wouldn't be scared off by a good deal on wheels with a carbon rim, but prefer the aluminum Hed type of design.

Tubular vs. clincher

There are long standing debates about the relative merits of tubular vs clincher wheels, but I think it is fairly clear that clinchers have won.  Clinchers are far easier to deal with; a flat can be changed with a simple tube instead of gluing an entire new tire ($$$).  Tubulars are generally lighter, but I'll reiterate that doesn't matter.  They are aerodynamically equivalent and you can find equally fast tires for both, in fact finding good clincher tires is generally a bit easier and cheaper.  With tubulars you have to be careful that you buy one with latex tubes which manufacturers often don't make easy to decode.  Sounds like that makes this an easy decision, right?  Well, not exactly.  If you are a bargain hunter and are willing to put up with the trouble, you can find some really good deals on very fast tubular wheels.

Wheel cover vs. disc

Disc wheels are fast and can actually improve stability, so you should probably be using a disc.  However, they are pretty expensive, running as much as $1500 new, which seems like a lot for a wheel that you are unlikely to ride other than at races (lots of people are willing to rock their deep wheels all the time, but for some reason many fewer ride a disc all the time).  It turns out that you can buy a wheel cover for under $100 that will turn your training wheel into a disc.  A wheel covered wheel is aerodynamically pretty much equivalent to a "real" disc.  So why would you not do that?  It comes at the cost of some minor maintainability annoyance compared to a disc wheel.  The wheel cover needs to be installed carefully and if you want to take it on and off, you need to do that with some care.  If you are the type of person who does your own wrenching on your bike, this is not a problem.  If you have a shop do everything for you, this may be less appealing.  Especially because that $1500 new price tag can be more like <$500 for a lightly used disc.  At that point you are talking about a <$400 premium for ease of use and something that you may later be able to resell and the issue is less clear.

My Key Recommendations

1. Weight doesn't matter.
2. Always use a disc rear unless the rules prohibit it (e.g. Kona).  A disc cover is similar aerodynamically to a "real" disc and is cheap.  Even "real" discs can be had for <$500.
3. Go deep in front as long as you have a deeper rear (e.g. a disc).  A deeper rear wheel will be more stable and handle more reliably.
4. Match tire choice to your wheels.  Narrow wheels need narrow tires.  Make sure you can find fast tires/tubes for your choice of wheels.  No point getting aero wheels and throwing away the advantages with butyl tubes and high Crr tires.
5. Go used over new. Tubular are annoying, but are cheap used and can be good bang for the buck.

Example "Good" Choices

• Budget constrained: Existing rear wheel with a wheel cover + a used deep front. Something like a Jet6/9 or Zipp 404/808 or H3 can be had relatively cheaply and provide good value.  Getting a previous generation (e.g. non Firecrest Zipp's or the non SCT Jets) can easily make this a sub $500 setup that will be close to as fast as a the best possible expensive setup.  I don't have experience dealing with a disc cover myself, but there seem to be both positive and negative experiences.
• Best in class aero: Hed Jet9 front, Hed Jet Disc rear.  ~$1500 used.  Aerodynamically top notch, durable, clincher, alu brake track.  Note that a Zipp FC 808 front and Zipp disc are aerodynamically similar, with the main difference being carbon brake track.
• Budget constrained new: Flo90+Flo disc.  ~$1100 if you can get in on one of their orders.  I don't have personal experience with them, but their story seems good.  
• Kona bound: Jet6 front/Jet9 rear or Zipp 404 front/Zip 808 rear + wheel cover.  Race all the non-Kona races with your disc cover and use the wheels without the cover at Kona.  Of course you could also just buy multiple sets of wheels :)
• Totally tubular: Lots of great used options if tubular doesn't bother you.  I'm selling my own H3 front+disc for almost nothing and they are as fast as you will find.  On the slowtwitch classifieds forum, tubular wheels (e.g. Zipp 808s) regularly languish waiting for offers while equivalent clincher's get snatched up almost instantly.

What do I Own

I currently have a 2012 Jet9/Jet disc that I purchased used and am very happy with their performance.  They are very fast, stable in the wind, seem durable and have been very easy to use (e.g. clincher with aluminum rims).  I feel like they are compromise free wheels apart from cost.  My first set of race wheels was a pair of Hed3 carbon tubulars.  They are really cool and fast wheels (I love the way they look), but they definitely had more compromises than my current wheels.  I had to learn how to glue tubulars and worry about changing a tubular during a race (which fortunately never happened to me and can be helped by pre-treating with sealant).  The carbon brake surface required special brake pads and while fine is not as good as alu.  They also felt noticeably different than shallow rims in the wind; I found that they were predictable but took a little getting used to.  My "second" set of wheels was when I bought a rear tubular disc to use instead of the H3 rear.  That was a very incremental improvement; a disc is slightly faster than the H3 rear, and it improves the overall handling a bit.  On the plus side, these wheels were much less expensive than my current wheels and just as fast.  An H3+disc is typically the choice of guys like Bradley Wiggins and Chris Froome, while the Jet9/Jet disc is typically used by the likes of Tony Martin, so clearly either set is pretty fast!