12

I'm doing research for a future purchase of new wheels (for everyday riding) for a 2012 Cannondale CAAD10 Ultegra. I want to spend ~$1000 (give or take $200 or so). In my price range I've found: Boyd Cycling, Williams Cycling, November Bicycles, and Soul Wheels (a bit over price range). They all offer similar wheelsets for a similar price. I'm specifically looking at carbon clinchers.

I live in Sacramento, CA (very flat city), am 6ft tall, 130lbs.

Two questions:

  1. Now that I've identified some different brands, how do I choose between the brands?
  2. How do I choose rim depth (38mm vs 50mm vs 58mm seem to be the commonly-used ones)?
1
  • Maybe this will help,I went with the Chinese 88 mm wheels and have put many miles on them without have any adverse effect from crosswind!I'm a solo and group rider and I love these things.but you do have to use valve extenders, I'm using a standard presta valve length tube with a 71mm extender.
    – user14185
    Commented Oct 25, 2014 at 15:14

6 Answers 6

9

The full answer depends on where you are riding, how you are riding, and the conditions you are riding in. Windy, winding, hilly courses that you tackle on a road bike with some friends would have me leaning towards a less deep set of wheels. A flat calm straight triathlon course on a tri-bike I'd want more depth.

With the wheels you are looking at, and the price range you are looking at, you aren't going to be getting into the newer shaped wheels (like the Zipp Firecrest and other similarly shaped wheels) that work especially well in cross winds...which means the depth will come into play if you are in a windy situation.

My bottom line would be go with shallower wheels unless you have hard reason to go deep. The slight aero benefit of the deeper wheels will be outweighed by the greater versatility of the shallower ones. With the exception of the latest tech in wheels (Firecrest shape) my #1 criteria is hubs...a great hub on a so-so rim is much better than a so-so hub on a great rim...keep that in mind when making final decision.

If possible, ride on a set of the wheels. Find a friend that has a set identical or similar to the ones you are thinking about and take them on a typical ride (not just a ten minute test).

Also: I've been recommending folks to consider semi-carbon (carbon with alloy braking surface). These are a bit heavier, but not much and you won't have to change brake pads moving back and forth.

Have fun, be safe.

3
  • 1
    Why do you think hubs are so important? Even the cheap Shimano 105 hubs work perfectly fine, though they weigh a bit more.
    – Michael
    Commented Jul 26, 2015 at 11:56
  • It's not the weight of the hub but how smooth the hub turns that's important. I've built wheels with Shimano 105 hubs and they are okay, but my Hawks are faster.
    – Ken Hiatt
    Commented Jul 31, 2015 at 2:48
  • 1
    I really really doubt there is much difference. Any properly maintained hub/bearing will run very smooth.
    – Michael
    Commented Jul 31, 2015 at 10:42
9

These 38/50/60/88 numbers are the 'depth' of the wheel's aerodynamic rim, in millimeters. Let's take 38 for example. This means that from where the tire meets the wheel, the rim extends an additional 38 millimeters towards the hub. When you see 88, that means the rim extends 88 millimeters from the tire.

Why does that matter? One of the biggest benefits of carbon wheels is the aerodynamics. They play a major role in how fast, and how efficiently a cyclist can ride. Think back to when you were on a ride with your buddies, and drafted behind another rider. It's much easier to keep up with them, because of the better aerodynamics when you are drafting.

Your spinning wheels are the biggest source of slow aerodynamic turbulence. To improve this, we build wheels with aerodynamic advantage as a top priority. The way we do this is to increase the 'depth' of the rim. The deeper the rim, the more aerodynamic the wheel will be and the more efficiently and faster you'll be able to cut through the wind. An 88mm deep rim is more aerodynamic than a 38mm rim, and will be faster in situations where aerodynamics are very important, like long fast solo riding and triathlons.

Why would anyone choose 38mm rims, if 88mm rims are more aerodynamic? The more a wheel becomes aerodynamic for going forward, the more it can be negatively affected by cross-winds, or winds coming from the side. Let's imagine you are riding with an 88mm deep front and rear rim. You will be able to go very fast because of the aerodynamics of deep wheels, but if a gust of wind comes from the side, that wind will push sideways against the large rims and push the whole bike sideways. This isn't such a big deal if you're riding alone, such as in a triathlon, but if you are riding in a group of cyclists, this sideways push could cause an impact with other riders, or at the very least it would require extra concentration from you.

What's the solution? A wheel with a 'shallower' rim depth, like a 38mm, will be less affected by crosswinds, but will also have less aerodynamic advantage.

If that wasn't enough, you must also consider weight. A 38mm deep wheel will be lighter than an 88mm deep one, because less carbon is used. A lighter wheel will accelerate faster and will be much easier to ride up hills. This means that if you are sprinting and hill climbing a lot, a shallower rim, like a 38 will be best.

Why do I see some riders with different front and rear wheels? Due to the fact that the front wheel can turn for steering, its more susceptible to cross-wind interference. The rear wheel is fixed in a straight line with the bike, so if a cross-wind hits it, the impact on the bike won't be as much. This means that you can use a deeper rim on your rear wheel without impacting handling as much as that same rim would affect the front wheel. Wheelsets such as the 38-50 to take advantage of this fact. This wheelset uses a 38mm front rim, and a 50mm rear rim. This way you can get more aerodynamic advantage without sacrificing as much stability in windy conditions.

How do I choose? This is the most difficult choice for riders looking to purchase new carbon wheels. You must think about the situations you ride in. If you ride mostly hills you will want to choose a 38mm wheelset, if you are an all around rider choose a 50mm wheelset, if you are an all around rider looking for more aerodynamic advantage choose a 60mm wheelset, and if you are a solo rider, or a triathlete choose an 88mm wheelset.

1
  • 3
    All sounds pretty good, although people vastly overestimate the impact of wheel weight on acceleration. The difference in power demand to accelerate wheels with such weight differences are measured in milliwatts, if not microwatts, it's so tiny a difference. Indeed aero is far more important in acceleration performance than wheel weight. See this link for an explanation: alex-cycle.blogspot.com.au/2013/02/the-sum-of-parts.html As for climbing, well even then aero still matters and it's not until the gradient is steep that absolute weight outranks better aero properties of a wheel. Commented Oct 28, 2014 at 0:29
3

I live in Dubai, also a very flat city. My experience says if your average ride is flat and fast, go deep, unless the area is extremely windy.

My family is from the Bay Area originally, and I've lived in Napa and Sacramento. For Sacramento, and in your budget area, I'd look at something like he Altair 80 Carbon Clincher from Profile Design.

They are good, if a bit heavy, full carbon aero wheels. They come in a 52mm deep and an 80mm deep, in both tubular and clincher varieties.

They are fast, aero, and strong. They cut price by not cutting too much weight, so there are better options if you want to raise your budget, but not in that price range.

1

As for what wheel to choose, well that's such a complex combination of factors, hard to provide a simple answer. I outlined some of the considerations when weighing up choices in my blog post I linked to in an earlier comment on this thread:

They involve a range of factors, including, inter alia (and not in any particular order):

  • strength
  • durability
  • aerodynamics (in low and higher yaw conditions)
  • wheel mass
  • ability to stay round and true
  • lateral stiffness
  • cost
  • repair-ability and service cost
  • warranty support
  • suitability for the purpose/race/riding situation
  • braking demands (and issues with brake pad choice, long downhill braking scenarios and wet weather)
  • handling characteristics (cornering, cross winds)
  • available tyre choices (and level of difficulty in changing tyres/tubes)
  • bearing and freehub quality etc
  • rules of competition
  • suitability for the bike (e.g. will it fit?)
  • sex appeal / bling factor and so on.....

Then one needs to weigh up those factors and apply their own personal judgement as to which factors matter most and fits within their budget. That will of course be different for everyone. It's no wonder wheel manufacturers have a field day with all the various possible points of difference available when marketing their wares.

1

The original question was asked in 2012, when almost all road bikes had rim brakes. Of the wheel manufacturers/builders the OP identified, one (November Wheels; disclosure that I'm a customer) builds mid to high end off-the-shelf rims and hubs; in the former case, anyone could buy the rims and build them up, and possibly even rebadge the rims under their own branding (with consent from the manufacturer). Boyd (disclosure, I have a pair of rims from them) has their own rims made in the Far East (I believe the profiles are proprietary). I'm less familiar with the other two, but I'd assume they operated similarly. In contrast, higher-end wheel manufacturers (e.g. Zipp, Enve) design their own rims and have them manufactured. This may be at their own factories (Enve), or they may have an exclusive arrangement with a factory.

All else equal, higher-end wheels may have more complex rim profiles, and they probably have access to better computer design (e.g. computerized fluid dynamics simulation) and wind tunnel or other field testing. Lower-end rims presumably go through less intensive development. I don't have any specific knowledge of this, but I wouldn't be surprised if they copy (either wholesale, or modify slightly) the profiles from other established wheels. As road wheel design has evolved, I don't think that the aerodynamics for a given depth are materially better today than 10 years ago. However, modern profiles are likely to be more stable in crosswinds. That might inform your selection between a high-end manufacturer and a lower-end seller using off-the-shelf (sometimes called open mould) rims.

Selecting among different off-the-shelf rims is harder. You can comparatively test wheels using the Chung Method of field testing, if you have an accurate power meter, a speed sensor, and some time and technical inclination. However, this involves getting your hands on the wheels, so testing many of them probably isn't practical. There are some more basic criteria you should focus on first, particularly internal width. This affects the actual width of your tires. In particular, 21mm internal widths are aerodynamically optimal for up to a 25mm road tire. In the road context, 23-25mm internal widths will be aerodynamically optimal for a 28mm tire. If the tire is too much wider than the rim, it will increase the amount of drag. (The magnitude of this effect is probably modest, maybe in the range of 5-9W at 25 mph, but I'm basing that off memory from various podcasts like Marginal Gains.) Many gravel wheels are gravitating towards at least a 25mm internal width, so that might also influence a buying decision.

And naturally, you can also ask about weight. I can't exactly recall what the situation was in 2012, but I think that modern road wheels don't focus heavily on low weight except at the very high end. In part this is because we've had experience about how light you can build a durable wheel. Also, we now know that weight has relatively little effect on performance.

Rim depth is the key parameter that influences weight and aerodynamics. In my experience, roadies will probably select up to a 50mm depth, sometimes 60mm, for general use. Crosswind stability is one thing to worry about. And in general, the deeper the wheel, the less stable it will be in crosswinds. However, there are two aspects to crosswind stability. First, a bigger surface area means you get pushed laterally. Second, each rim has a center of pressure relative to the hub. Crosswinds will produce a steering moment, and I believe that this is much more unpleasant than just being pushed laterally, especially when it's a gust of wind that you didn't expect (and suddenly you feel like the bike is making an uncommanded turn). This 2014 blog post by November Wheels discusses that concept. As mentioned above, however, with increasing development, even the off-the-shelf rims have increasing crosswind stability. For the same amount of side force, lighter riders should be more disrupted by a crosswind or gust than heavier riders, so lighter riders may have some reason to prefer shallower rims. However, we also produce less power than heavier riders on the flats, so this might counteract that preference.

I don't know how much aerodynamic drag differs between depths. The amount of difference might not be enormous. For example, Flo Cycling's 49mm rim brake wheel claims to take 20.50W to spin at 22mph with a 25mm Continental GP 5000 tire, versus 19.78W for their 77mm deep wheel. The difference between something in the 50mm range and something closer to 35-40mm deep might be larger, however.

0

Personally, I ride with a HED Jet 4 on the front and a Jet 5 on the rear. I ride in the Northern California Hills so climbing is a major consideration. I was initially cautious about going so deep because I feared that I would suffer in long sustained climbs. My times climbing were not adversely affected. In fact, I achieved some personal bests in climbing probably due to the stiffness and unique lacing. I don't know. However, in descending and on the flats the difference is huge. I should mention that before I had a set of Jet 4's and cracked the rear rim after 3 years. I replaced it with a Jet 5 and was faster. Previously I had owned a pair of Bontrager XXX Race lites (an all carbon wheel set). I loved these and rode them until I crash....After the crash I got the HED wheels and the deeper profile increased my speed and I set a lot of new personal records. I was surprised that about my speed increase especially moving from a 1200 gram wheel set to ~ 1650 grams. So, I concur with the previous commenter about having a slightly deeper rim in the back. 2) Deeper profile wheels make a significant difference. 3) Go as deep and light as your budget will allow!

Other comments: Cross winds are not a significant factor unless they hit you flush at 90 degrees, which happens very rarely. The other benefit of deeper profile is that once up to speed, they hold that speed with less work which means that you save a lot of energy on long distance rides.

1
  • i dont know about crosswinds hitting you flush at 90%.
    – nolawi
    Commented Feb 28, 2017 at 3:59

Not the answer you're looking for? Browse other questions tagged or ask your own question.