The Latest

FEATURED BUILD - Pacenti SL25 with WI CLD and CX-Rays.

Pacenti is rolling a new rim for 2017 but we can't imagine why. The SL25 has been a deserved customer favorite since it launched. Save $100 while our inventory lasts.



Subscribe to our emails:

Our emails include resources, tips and insights to help make you a better cyclist and a more informed buyer, whether you buy from us or not. If you like, sign up below and we'll send you the next one.

Site Search

Aerodynamics thoughts

This week, the Al33 and a number of other rims will be tested in the A2 wind tunnel in North Carolina. We aren't paying for it, it isn't our test, but we agitated for it to happen, facilitated all of the arrangements, and designed the test. Without those inputs from us, the test wouldn't have happened. Call our stake sweat equity. We won't be there, but the US distributor will be, and we will be there in virtual.

I'm excited. I love testing, I love the wind tunnel, and I've learned a lot every time we've done it.  

The test will use a 2017 model Zipp Firecrest 303 as a baseline. Tested wheels will be a HED Belgium+, a Kinlin XR31T, the Al33, and a Flo30. All wheels are 20h rims built with CX Rays and standardized hubs, except for the 303 which is of course an 18h wheel which uses Zipp's own hub and CX Sprint spokes. 

The test will be done as a wheel only test. This has plusses and minuses, but it's proven to be an accurate way to test wheels and it allows wheels to be tested in a time efficient manner, which means we can include more wheels.

Test tire will be a Continental GP4000sII in 23c size. There will also be a 25c GP4000 there, how much testing gets done with it depends on time available.

All the quantitative data on each rim/wheel will be presented - depth, weight, inner and outer width, and retail price. 

We'll be doing the standard 20* sweep in 2.5* increments, on one side. Since these are all symmetrical front wheels, doing both sides would take time that would reduce the number of wheels we could test. We will also include steering axis force data as provided by A2. 

Not entirely certain how the data will be presented. My inclination is to show the standard graph like you've all seen 100 times, and then overlay some of the more defensible angle of attack distributions over top of those. It makes the most sense to then use those distributions to create a one number score for each wheel. 

I'd encourage anyone who wants to get the most from this information to become as informed as possible about the benefits and limitations of aerodynamics testing. Tour Magazin is an amazing resource, and you can go to the App Store, download their app, and buy issues for about $3 each. Issue 8 from 2016 is particularly good. Become familiar with the other methods like Chung and Alphamantis. 

A few bullet point thoughts:

1. Any quantitative test will have some strengths and weaknesses, but no wheel can make aerodynamics claims without credible quanification that allows at least some comparison to relevant standards. It shocks me how many brands still try to skirt past with a "trust us, we're fast!" line of bull. If the whole sales proposition for any wheel is that it's fast, yet it shows no data, I think you know what I'd say to that. This principle is why we insisted that the Al33 absolutely needed to be tested. 

2. Depth and speed are not interlocked. We first showed this four years ago when doing the original Rail 52 test, where the 52 proved faster than even the 85mm wheel than we'd been using, and was faster than the deeper Zipp 404 at angles from 0 through 5 degrees. 

3. We're still using the GP4000 in 23c size because that's been the standard, and it's still a VERY widely used tire in situations where aerodynamics are important. Our previous tests showed a reliable pattern that wider tires had a linear and predictable negative effect on outright aerodynamics. 

4. The Zipp 303 gets used "as is" because it's a wheel system, and its value as a baseline is in using it as it's been used in other tests. That allows you to make worthwhile comparisons to the greater universe of what's out there.

5. Have reasonable expectations. In the Tour Magazin test I referenced earlier (seriously, download it), the difference between best and worst was 13 watts. That's 40ish seconds in a 40k TT at 30mph between a Mavic Ksyrium and a 404 and DT Swiss 65, which were the fastest wheels in the test. That's about .4mph, worst to first. Anyone telling you you're going to go 2 or even 1mph faster by just switching to more aero wheels is selling you a load of crap. 

Okay, that's it for now. Looking forward to Thursday. 



Dave's road tubeless doubts

This post deserves a TL:DR summary, which is: If you aren't super comfortable with road tubeless and willing to spend some time and expense figuring out exactly which combo works for you, and also willing to petentially suffer a reduction in the lifespan of your wheels, stick to tubes. With a whole bunch of data now showing superior rolling resistance with clinchers and latex tubes, that may be the best way to go in any case. The ability to use latex tubes is another bonus of aluminum rims. 

For mountain bikes, tubeless is mandatory. For cross, it has its challenges (which we've done a heck of a lot to help eliminate) but the benefits can be so profound that the juice is for sure worth the squeeze. For road, though Mike and I personally use tubeless, we haven't been evangelical. It comes with downsides, which we'll talk about here. 

A potential "do as I say and not as I do" instance

We've been observing and talking about spoke tension drop in clinchers for a couple of years now. Since I've done THE WORST job at tagging posts, it's hard to find all the posts on the topic, but these two posts from last spring are good examples. There were a bunch of forum discussions in the spring of 2014, but I can't even recall which forum they were on. We even made a video to show the effect last spring. 

Wheel Fanatyk has what might be the second best wheel blog out there, and they did a series of posts in the fall about this whole topic, including the outward splaying of brake tracks which we'd discussed in above-linked post called "Pressure Drop Follow Up." What they did in particular, for which I have huge appreciation, is measure a bunch of tires to find how tightly they will fit. Their whole methodology and execution of this is excellent. What their measurements reveal is something that anyone who's installed more than one kind of tire will already have known - tire bead circumference varies by manufacturer and model. 

They've also measured overall circumference of a number of different rims, but they haven't shown the more relevant tire trough and bead seat diameters (which are simple secondary measurements from what they've done and shown). The overall circumference is of little value in its own right as, for example, a Zipp 404 shows a large outer diameter, but 404s are known to be relatively easy to fit tires onto (perhaps too easy?).

In order to resist the higher inflation pressures of road tires, road tubeless tires need a tight fitting carbon bead. The carbon bead more or less doesn't stretch, which is critical to having the tire not blow off the rim, and thus to keeping your teeth in your head. In that respect, it works quite well, but at what cost?

Non-tubeless road tires have either wire or Kevlar beads (if you're reading this, you probably have Kevlar beads). You probably notice that your tires get easier to install over time, which is because the beads stretch a bit over time. This stretch reduces the constricting pressure that the tire imparts on the wheel. 

Compressive tire loads cause a reduction in the circumference of the rim. Wheel Fanatyk estimates a possible 1mm reduction in the circumference, and my calculation gave me an estimate of .1mm in diameter reduction, so they estimate a bigger effect but we're not that far off in the absolute. I based mine off of "the spoke tension drop is x, the thread pitch of a nipple is y, the spoke tension drop is equal to z turns of the nipple, therefore the diameter reduction must be..." The important thing is that we're both seeing the same effect, in the same direction, with reasonably similar magnitudes. 

Compression is bad for the wheel for several reasons. It takes more initial spoke tension to maintain the minimum necessary functional spoke tension. Compression changes the dish of a wheel. Compression puts stress on the rim that almost certainly shortens a rim's useful life span. 

At the risk of speaking against my book somewhat here, I have two road bikes in current use (one disc, one rim brake, otherwise more or less identical) and those four tires are all tubeless. It works fine for me, but on a scale of 1 to 10 in tubeless experience, I'm about a 643. So if you are willing to invest time and money into getting your road tubeless set up perfectly, knowing that it comes with the potential to compromise your wheels, then it may be worth it to you. Otherwise, tubes are your best bet. 


Al33 Rims and inflated tire widths

Here are some measured inflated tire widths on Al33 rims, which we use in our RFSW3 wheels. The inner width of the rim is 19.6mm, which puts it in line with many of the current popular wider rims. There aren't a lot of surprises on this list, and with these data points it's possible to interpolate/extrapolate most of the other tires out there.

All tires inflated to 95psi prior to measurement. Format is tire make & model / size / inflated width:

Continental GP4000sII / 23 / 25.65

Continental GP4000sII / 25 / 28.60

Specialized S-Works Turbo / 24 / 25.40

Specialized S-Works Turbo / 26 / 27.15

Maxxis Padrone TL / 25 / 26.50

Michelin Pro4 SC / 23 / 24.5

Again, no huge surprises. Every tire is somewhat bigger than stated size, and GP4000s considerably so. With an outside brake track width of 25 and an overal widest width of 26.2, the rims themselves shouldn't cause fit issues with any frames we know of. 

We have helped to arrange a wind tunnel test for Al33 and a bunch of other comparably relevant wheels on 2/9. We will post the information from that as soon thereafter as possible. I can assure you that we're as curious about that as you are. 

Following that test, we'll make the order pages live. 


Which hubs are for me, part 4: Industry Nine Classic Road

Apologies in advance, this one will be a little photo light. I somehow mangled an SD card and we don't have any I9s in stock right now. They're expensive to carry and with each drilling opion in 11 colors and no color having a popularity edge, they're difficult to stock. 

That said, let's do the numbers...

I9's Road Classic Torch hubs (ain't that a mouthful?) are simple, elegant, beautifully made and finished hubs. Their specs are great (the front geometry is really great), they're light enough, they require bupkus for pre-use setup and are low maintenance, and they are made in one of the all-time awesom hippie towns in the universe - Asheville, NC. 

Axles are aluminum, as is the cassette body. The cassette body is subject to a bit of chew, nowhere near as much as DT cassette bodies (made of butter, apparently) but they're not ti. I've seen hints of a steel option, of course that adds weight. Bearings are straightforward, well sealed, and have no adjustment mechanism. That's either a plus or a minus for most people, but can also be neutral. Depends on you.

Yes I know this is a disc front hub, but the road hub's end caps (front and rear) are similar. That little sucker in the bench vise is called an axle vise, and you need it (or some other elegant solution, but an axle vise costs like $6) to get the end cap off. They're no chance going to fall out on you. The end cap does a good job of sealing out any gank from the bearings. 

The rear drive mechanism is standard drive ring and 3 pawls. 60 points of engagement, so the pickup is more or less instant when you pedal. They're fairly loud hubs. Not like their mountain bike hubs, which are sure to draw comments, but you notice them. 

Seriously this is the most handsome set of wheels everIt's tempting to compare the I9 hubs with Novatec, as they share a similar simplicity and straightforwardeness. The front hub geometry on the I9 is just plain better, but whether that's a functional difference is not absolute. If we'd experienced or heard of shaggy front wheels with Novatec hubs, I could say it is, but we haven't. I'd certainly be more comfortable putting some bull moose knuckle dragging crit sprinter on a 20h I9 front than an otherwise-equivalent Novatec front. For people toward the center of the bell curve? Not such a difference. Kind of same with the rears, although the geometry differences are less stark there. 

My sister-in-law uses this word that my brother (who's way more of a skin flint than I am) just hates, which is that she will describe something that's really elegant as "rich." Maybe she watches too much Project Runway, I don't know. In any case, I9 hubs positively exude "rich." It is impossible to experience an I9 hub without knowing that it's an elegant product. And it's not a false impression, their functionality matches that impression.

Gratuitous beef cake shot

So again, as some comments have discussed in previous posts in this series, we try to give you the objective as well as we can, so that you can either tame of unleash your personal subjective in your decision process. I totally admit that the other day I was sort of hemming and hawing to go out for my ride, it was cold and windy and I'm sick of cold and windy, and the flashy neon yellow logos on my wheels were like a dog bouncing around excited to go for a walk. I smiled and hopped out for a great ride. Anyone's relationship to his/her bike and riding and that whole ball of wax involves a good bit of alchemy, and the hippies at I9 are darn talented alchemists. 

My mtb wheels, which force many "hey - my eyes are up here, thank you!" moments. And lots of drool


Feature Build: SL25/CLD/CX Ray

Over the past two years, one of our most popular, reliable, and best builds has been crafted from Pacenti SL25 rims, White Industries CLD hubs, and Sapim bladed spokes. Pick whatever attribute you most prize - light, stiff, strong, durable, great looking, reliable, versatile - and it's got it covered and then some. And we're discontinuing it. Not of choice, but of necessity. The SL25 will soon be replaced by a new version called the Forza, so we're offering our remaining SL25 rims in a feature that could easily be our favorite all-time build, at $100 off our already "lower than anything even remotely close to as good elsewhere" price. 

Sex may sell, but nothing in the bike industry sells anywhere near as well as "new." Will the new rim be as good as the SL25? It's tough saying without knowing. What we do know is that we've loved the SL25, and we're sorry to see it go.

As to the build, it needs little explanation at this point. For road, gravel, cross, or whatever path you might choose, it's as good as it gets. It's always been our first choice for cross tubeless. CLDs feature the same steel axled, titanium cassette bodied general awesomeness as T11s in one of the most reasonably priced premium hub sets on the market. CX Ray and CX Sprint spokes speak for themselves. 1640g for the package in 24/28. And having built this exact combination hundreds of times, our ability to put it all together is unequaled. 

Inventory constraints limit us to 24/28 and 28/32 builds, in limited quantities. Choose black or silver hubs. Includes tubeless tape AND VALVES. Give us about a week to get them on the way to you. 

Pacenti SL25 / WI CLD / Sapim CX-Ray Featured Build.