Chandne

Well, my sub-300 gram wheels certainly spin up faster than my 1800 gram wheels on the MTB. If I swap to lighter tires, the difference is even more significant. Plus, all my climb PRs are on the lighter wheelset, so I ordered a darn light MTB as well this week and will just get the best of both worlds. The 33 lb bike can keep the 1800-gram sluggish wheelset for trail blasting. and my 23.5 lb race bike can keep the sub-1300 gram wheelset for racing.

PeteHski

Your wheels are still only a small percentage of the total weight you are accelerating, even when accounting for rotation.

So if say your total mass was 85 kg and you accelerated at 5 W/kg ie 425W. If we reduce your weight by 1 kg (the equivalent of 500g of rotating rim mass) now you only need to produce 420W at 5 W/kg. A saving of 5W and only while accelerating at a high power output. It’s not nothing, but talk of spinning up wheels faster is really nonsense.

On a steady state climb you get more of an advantage from the weight saving, but then it’s just the same effect as static mass. You can plug that into one of the bike mass/power calculators to see the effect of 0.5 kg weight saving on a given slope.

Chandne

I donlt think it is all about weight savings but where that weight is. First there is sprung vs. unsprung weight, and then pure rotating weight (rim/tire). I just look at the data (power/HR) and compare the two when I swap wheelsets on climbs (mainly climbs...I do not bother with the lighter wheels when climbing a flat 30 miles with 1K-2K of climbing). I am always faster on the climbs and I always accelerate faster when on wheels that are 500 grams lighter. Of course, if I swap to lighter/faster-tread tires, the diff is pretty significant. I usually swapped wheels when climbing 3-6K in 20-40 miles. So then I figured...now I see why racers use light wheels AND light bikes. So why not me! Well, in comes the 23.5 lb Specialized Epic!

SoSmellyAir

Wow!

This pretty much describes almost all of my bike rides, so I guess I should be glad I ordered the deeper wheels.

genejockey 

You just need one of these...

Chandne

Haha sorry- sub 1,300. My experience with light wheels mostly centers around mtn biking. The climbing and also the stop-go technical sections. We can do that dozens and dozens of times on a ride- there light wheels and light bikes are so much more fun and easier on the body. On the road and for flatter rides, you may not feel as much of a difference between wheels 200 grams apart. My ZIPPs are pretty darn light but compared to my ENVE Foundation 45s, they really just feel very nice...compliant, light, springy. If I had a chance to get even lighter wheels, I probably would, but the 303FCs are the lightest road wheels I have ever owned.

SoSmellyAir

I thought you must have been describing rim weight; a CF rim < 300 g is pretty light.

Those are pretty light, but at 90 kg, hookless are not for me.

Maelochs

I have a dinosaur 26" MTB with very light Industry Nine wheels, and since I don't ride long MTB trails, (well, I don't ride MTB at all lately but when I was fit for it) but mostly stuff carved out of limited space with an emphasis on features (climbs, descents, corners packed in tight) which suited fast wheels.

On a road ride the difference might be negligible because one only really stops/starts a very few times (assuming an actual road ride, not a closed-course event) so those few seconds of joy in an hour or two 's ride don't mean much numerically (if only engineers could measure happiness, eh? ) but on a constant-spurt dirt ride the difference seems more substantial.