It’s the tension in the spokes that provides most of the load bearing capability of a wheel. Aside from that being an established fact, how else could you explain that a rim that would collapse if you sat on it, can support you, your bike and the force of riding impacts once it’s built into a wheel? Perhaps you’re already familiar with the concept of “superposition of forces”, but if not, look it up in relation to bicycle wheels. It’s counterintuitive and fascinating, as it explains how a bicycle wheel effectively stands on its bottom spokes.

Right, I believe Dustin’s data involves testing the rim only. It does give an idea of how much stiffness is derived from the spokes, which need to resist this deformation.

Bnystrom is right and Dustin’s chart with 10mm rim deflection has to be rim only as 10mm detection would have spokes poking holes in rim tape at the bottom and snapping or ripping out of the rim at the sides. This “compliance” thing is marketing BS – the only detectable factor in lateral or vertical compliance is tyre (yes, I’m a Brit) deflection.

Cheaper, sure, but easier? And you can’t reduce rotating mass by dieting.

The last few times I’ve been in there I’ve found myself wandering around for 30 or 45 minutes just to find someone to ask a question as simple as “do you have anything else like this here.” Employees have at best been polite but confused, with seemingly zero knowledge of the products or the store or anything else, at worst unhelpful and openly irritated to be talking to me. “I don’t know, sounds like you’re looking for something specific so you should probably just look it up online.” So I don’t shop at REI anymore. Seems like a company in a death spiral. Too bad!

Just added this place to my bucket list!

Yeah, the title might have gone too far. The idea is to ask yourself, “is my bike heavier than it has to be?”. If the answer is no (or if you don’t care either way), that’s fine! I just know that I’ve noticed weight creep on my own bike over time, and for me the easiest weight savings have come from “downgrading” my tires to thinner casings since I rarely flat, and consolidating my stash tools. That’s easily saved me a couple pounds.

Great point about percentage changes representing very tiny changes in measured rim deflection. And yeah, adding a couple psi to your tire pressure, for example, is going to change the ride feel more dramatically than the changes to rim properties we’re talking about.

Dustin conducted some of his own rim deflection tests and provided a chart to me that shows deflections than range from 0.07 inches to 0.42 for a couple dozen MTB rims, which is actually a fairly significant range (on the order of 10mm, not just tenths of a mm). I don’t have the full details of his test setup, but it involved hanging a weight off various rims and measuring deflection. I suspect actual trail impact could be even greater.

When you slap a 60mm tire on a wheel, the vertical rim deflection under load is going to be so small that you can’t possibly feel it. When someone says otherwise, they’re either confirming a previously-held expectation (bias) or they’re perceiving something else. Tire flex and pressure are the overwhelming determinants of vertical compliance, not wheels.

Lateral deflection can be somewhat higher before spoke fatigue becomes an issue, though it’s still not a lot. A rim can also deflect torsionally (twist) when a load is applied predominantly to one side of a tire, which could be significant without a dangerous loss of spoke tension. I recently saw an article about a manufacture (I can’t remember who) that’s addressing this and trying to build it into their rims. I guess there’s potential there, but again, it may just be extremely small differences that don’t have a significant effect in the field. And again, tire construction and air pressure play a huge part, far more than any rim deflection.

Add suspension to the mix along with the variability of trail conditions, and it’s virtually impossible to draw any meaningful conclusions about wheel compliance in actual riding tests.

The article on this page touched lightly on the fact that riders vary dramatically in their preferences and riding styles, so there’s no one solution that’s better than any other. Given that, compliance claims seem even more like “smoke and mirrors”. While this may be entertaining to debate, getting out and riding whatever bike you have is a much better use of energy.

lateral stiffness of wheel is more than anything else dependent on the spokes. as aluminum rims have become wider their lateral stiffness has also increased considerably. never heard complaints of laterally stiff 40i rims. and they are super stiff in this direction.

they can however in absence of proper spoke tension be soft radially. soon you hear the characteristic playing sound of spoked retensioning themselves. not a situation that will go on more than shortly before spokes break from fatigue….

Gary , good commonsense approach .

As stated in my earlier post , the shorter riders “NEED” 27.5 offerings .

The shorter riders like myself , 5ft 6in tall , still have some mountain bike options of decent quality available to us . Particularly in small and extra small versions on the 27.5 platform . I ride 26’ers still and ride older courses suitable for them .

Good point! Though Evans wasn’t a gravel or cyclocross World Champ which at least involve a little bit of dirt haha.

There are trade offs with 29ers also.

Demand. It’s a free market and the majority of buyers prefer 29.

This should be #1. Unless you are in tip top shape losing body weight is cheaper and more no practical than spending a bunch of money of bike components.

Most are not you. 27.5 suits a fairly small market, mostly people short enough where a 29″ wheel causes fitting compromises, and a few that prefer them on the back of some longer travel rigs. The whole “no net advantage” you speak of doesn’t hold water.

Well you are not me.

Good tip, going 27.5″ is another way to save weight. Obviously there are tradeoffs in terms of performance, fit, etc. that each rider will need to consider for themselves. For some, 27.5 could be a win-win!

Hey Gary, there are still some brands producing some high-quality 27.5 bikes. Notably, Pivot recently released an all-new 27.5 platform, the Shadowcat. We also recently published a great article from a rider who went back to 27.5 from 29er, and it covered some of the best 27.5 bikes on the market. Be sure to check this one out if you haven’t read it yet: https://www.singletracks.com/mtb-gear/after-a-decade-riding-29er-wheels-i-returned-to-27-5-front-and-rear/

I for one haven’t ridden a full 27.5 bike in years, and have no interest in going back.

Jeff,
I think it was a big mistake for the mtn biking industry to stop producing 27.5″ bikes. So why did the mtn biking industry decide to stop producing them?

Oh interesting, I’ll have to try the Blue Moon!

Yes, safety is huge!

Thanks for the feedback. We do put a lot of thought into our weekly affiliate product picks, considering price, performance, and how many riders are actually buying/using these items. Do you think including more detailed product descriptions (ie context and comparisons) would be helpful? If so we can certainly share more info in the future!

I do ride tubeless. But I’m referring to the need to carry spare inner tubes in case of a flat tire.

Hey Jenny, thanks for the comment! Did you spot this recent article about Cincinnati?
https://www.singletracks.com/mtb-trails/bentonvilles-famous-mtb-trails-are-inspiring-trail-development-across-the-country-this-time-in-cincinnati/

We also have our eyes on a few more projects that are in the works!

Perhaps you’re right.

If I’m reading your comment correctly, what I think you’re pointing at is mindfulness during the ride — and I think that’s hugely important. However, I personally believe that one of the pinnacles of mindfulness is being mindful enough to know thyself, and I’m mindful enough to know that I won’t be satisfied by riding the same 10-mile loop every day for the next 40 years. From what I see on Strava, it seems like some people are, but I know for myself that isn’t it.

Cheers to a great 2025 on the bike either way!

Thanks Chris!

Thanks dlwason!