For anyone that sees this thread in the future and scrolls this far, I’ve basically settled on:
for a full carbon construction disk (lighter) in 2024, with a hooked rim and 20+ internal rim width. Not really valuing budget but more matching specs.
Thanks all for the replies!
I may be wrong but I think that PCW Blur 633 has an internal rim width of 19mm.
You’ve got a tradeoff here in terms of weight stiffness and clearance.
In my experience the light discs do flex a touch more so if you have a lot of stand up or big I’m efforts you may have just enough flex for the tire to brush your stays. Just depends on your bike.
Some allure the PCW given their image, but for my money I’d do one of the Swiss.
I did some very quick modeling. 200g extra weight over 112 miles means you will ride no faster or slower. It’s such a tiny amount of weight that it doesn’t matter…even over 112 miles. This quick model doesn’t take into account how much those 7 extra ounces will slow you down going uphill but I’m guessing not enough to worry about.
In real world racing you won’t see better or worse race results due to a 200gm difference.
Food for thought for anyone worried about a slightly heavier disc wheel
Did your modelling account for acceleration and deceleration on a lighter or heavier wheel? One thing that I’ve noticed with more technical courses is that a lighter rear wheel will allow slightly later braking in corners as well as quicker acceleration out of them.
The modeling I’ve seen doesn’t account for this, because it doesn’t actually occur. It’s a placebo effect. Rates of acceleration aren’t high enough in bicycles for a .2% change in mass to make a difference.
No. It’s a very simple model basically showing that 200g of weight is not relevant. There are a few posts on ST if you want to search showing that the acceleration and deceleration and the watts required/watts cost are much, much lower than anyone thinks they are.
I think braking into a corner or late braking is a skillset and a skillset that not a lot of triathletes possess
Have you (or anyone?) looked into the light bicycle disc ?
The price looks really good on those, and I’ve been impressed with their non disc wheels
I’ve not.
Sorry, don’t have any info on it
I’ve got a Swiss Side disc I’ll happily sell you…
It looks like ENVE are out of stock online of their disc wheel. I wonder what their timeline is for putting out a new one. I just put in an order- maybe I will tell them to wait…
I can certainly appreciate the lighter weight when I’m on a technical MTB course where you are doing exactly what you describe. But we’re talking literally hundreds of major accelerations and decellerations over the course of a race.
I don’t notice the weight on my Tri bike though and would think any loss in time would be nearly negligible.
The math isn’t any different for MTBing, it’s just that we tend to correlate a bike that “flicks” around more easily with one that accelerates more quickly. Pretty much the same type of feel correlation that led to over-inflated tires and overly stiff frames. Mass reduction in a bike definitely impacts climbing speed though, and it’s moving the dial any time you need to lift a wheel to clear something.
“Old” but still relevant I guess:
I understand and don’t argue the results you are coming up with. I agree on a Tri course and most road races this added weight is largely irrelevant vs all other factors.
I do think MTB is a slightly different beast however. I don’t feel the math can take into account force and fatigue required to spin up an extra .5-2lb of inertial weight and subsequent toll that has when at maximal effort for a 1hour all out puke when done race? This is where sometimes the data says one thing but real life experience can be different. There are just so many factors that aren’t able to be calculated in MTB because of the unconteolable factors are so numerous.
Again…I have no doubt that in Tri/TT settings that 100-200grs of weight makes no measurable difference of significance. Was simply trying to point out the very different environment of a true situation where accelerations are numerous enough to possibly have an effect that is not as easy to measure by mathematical models.
Ps …I always thought overly inflated tires was stupid! Again this was sort of math vs reality. I think the idea of high PSI tires probably holds true on a glass surface, but once you start putting variable road surfaces in the equation it becomes so far from the baseline equation that the it doesn’t hold.
The math holds up really darn well in both of the examples in question, it’s just tough to square that math with people’s “feels”. Heck, we’re seeing this happen yet again with inflation pressures as now folks have begun to correlate “fast” with “low pressure” and it’s becoming a bit of a struggle to get people to actually put enough air pressure in their tires.
Weight absolutely factors in to bicycle performance, it just doesn’t make a perceptible difference in rate of acceleration with the mass differences and rates of acceleration in play.
But hey, placebo effects count too, so if someone thinks their light wheels accelerate more quickly, there’s a good chance they’re going to accelerate more quickly when they put those wheels on their bike.
Yes the pendulum of opinion always swings. I can see how there could be movement to too low. Like anything there is optimal given conditions.
It appears Cadex has entered the thread.
“I would prefer to spend $2000 rather than $3000”.
Cadex turns around and leaves 100ft of burnt rubber on the floor as it disappears into the distance.
I’m gonna let “prefer” do some heavy work 
