I thought that this topic had been covered before, but I didn’t come up with anything by searching the archives. I am interested in discrepancies in claimed weight of disc wheels and actual weight. For example, on their website Zipp claims that the average weight of their 840 disc is 875g. Most of the catalogs I have here list it as 912g. I have heard rumors that actual weight is even higher than 912g. Has anyone weighed their own wheels? How about any bike shops? Tom? I know that Renn is right on or even a touch heavy in their listed weights. Other than Zipp what about Corima? HED?
Maybe it is pointless to harp about a couple dozen grams, but first of all we are talking about rotating weight which is important. More importantly Zipp and others want the consumer to pay a heck of a lot more than some of the competition for those few grams.
is that wheel even sold anymore? they claim the 909 as 950 gms, but I heard it weighs more like 1000+
for what it’s worth, rotating weight at that level make miniscule difference, maybe 1/100th of 1 second difference over a 40k time trial course, because you only accelerate twice - at the start up and at the turnaround.
i’m just kidding about the 1/100th thing, but it is likely not measurable outside the lab.
more importantly for a disc wheel is to consider bearings and reliability, which is why i always push corima
I weighed my standard hed disc a few years ago on a calibrated scale. It was 6gm lighter than the listed weight at the time. My previous was about 14 gm heavier than the listed weight.
more importantly for a disc wheel is to consider bearings and reliability, which is why i always push corima
-g
You know what I forgot about? My 909 rear had its bearings go out after about 300 miles (112 of that was on a rainy Lake Placid day)…I was pi**ed about that for a day or two. I picked up some new sealed ABEC9 bearings at a local bearing shop and no issues since. Who do we blame? Zipp as the OEM or the bearing company for putting out shitty bearings?
I weighed my 700c Corima disc at 950 grams which surprised me becuase they advertise the weight as 1000 grams. COst me $500 off ebay, I think Zipps are over rated and over priced.
From my experience with Renn: I have owned three incarnations of the Renn disc. My last new one was five grams under the spec’d weight.
One thing about composites in general: supplies have a lot to do with consistency. One can get a yard of cloth that is in general five grams heavier or lighter per yard. Nomex material can be five grams under. The suppliers of pre-preg cloth could have had a guy who was a bit heavy handed when coating the cloth. Even though epoxy pumps are “calibrated”, they can still make errors within grams of epoxy while pumping, or the guy mixing the epoxy could have just found out that his wife is cheating on him and pumped the pump too hard (in the case of a wet lay up). Vacuum pressure might not have been up to par on one day’s production. It is up to human error.
I like the TUFO approach to weight, and I suspect that they tend to quote their heaviest production samples as their claimed weight. This way, you find out their tyres are actually about five grams underweight.
What do I think of the claimed weight/ vs actual (heavier) weight of products? They either weighed their lightest prototype, or forgot bolts, nuts, clearcoat, decals or other things. Heck, one company even weighs their product without hub. Who can ride a wheel without a hub?
If it were me, I would quote my weights about 5% heavier (depending on the overall weight of the product), that way, I would always be toted as the guy who put things out at a much lighter weight. I would do that, or I would claim a weight range and the actual product weight would be engraved into the product.