The 'C' is not the shaft clearance, it is the internal clearance between the inner and outer race.

you and Hambini: super nice source of knowledge ;-) thank you both

I really appreciated the technical detail of this video, regards o

I have a decade or so in auto parts rebuilding and re-use of bearings is common. On my bikes I clean and re-grease bearings. I even made a jig to re-grease metal shielded bearings. All good so far.

I purchased pair of Zipp 303s end of January and waiting for Conti 5000 S TR tyres and better weather to arrive. Got the tyres - weather not so good but cant wait so going for the fit this weekend. Checked bearing numbers and front has 6903 E and rear has 6803 E. Not sure what to make of this but will check for any play/creaking after first few 100 miles . Thanks for the tip off re bearings which could be useful if I need to go back to Sigma Sports.

Thanks for the clarifying video! I was on the deep dive on 303S, as a 10+ years Zipp user (808, 808 FC, 808 NSW, for LD Tri). Now I'm looking for a road/CX set, and 303s was a good option. I will go for a DT240 + CX Rays+ 45mm rim, custom build by a experiencied wheelbuilder.

bought the 1st gen 303S - they were like water sponges and would not shed water caught in the wheel frame from 1 light rain ride (later versions drilled a hole to let water out during manufacturing). Support & product management offered to drill holes at the factory if I returned the wheels to their Indianapolis factory. Also the bearings were in such bad shape (rusted out) after 3 months of riding dry roads, and a few soft washes which Zipp refused to replace. This video explains why I had that problem - Thank you So much for lifetime warranty, and trying to save a few dollars on cheaper wheels (not that cheap) Thankfully the retail distributor accepted the return for credit as they had other customer complaints ---Zipp would not accept a return or replace. Will never buy another Zipp/SRAM product. Replaced with ENVE wheels and never looked back.

I've had numerous hub bearings sent to me for analysis, the bearings turned out to be fake and allegedly supplied by bike shops that sourced them from "bona fide" SKF and NTN dealers... Scandlous behaviour but it happens regularly. Stainless Steel bearings have a much lower load rating than "standard" bearings, Stainless steel is great for corrosion resistance but it's quite soft. Standard ZIPP bearings were/are made by HUX.

I use the Enduro SS angular contact bearings for my Trek Madone BB90. Hambini doesn’t seem to see their worth, but I’ve had good results with them. I like that they can handle (and require) additional preload during set up. I think AC is the right choice for a crank where you’re also putting in side to side force along with the up and down. I lift the seal off and put extra Phil Woods hydrophobic grease in there before install. The Trek BB90 non drive side has a bad problem with fluid ingress due to the frame shape and it funnels water right to the dust seal. I put extra grease between the bearing and dust seal and remove the crank every few months and clean and replace that external grease. Plus I’ve used 3M 2228 mastic tape trimmed and formed to create a tiny gutter above the bb area on the frame to sort of guide around and away any water coming down the frame from sweat or water bottle condensate. Rain forget it. As a result of all that, I’ve gotten great life out of my bb bearings, whereas before using standard bike shop fitted bearings, they were making noise usually within a year.

1:03 if you've ever packed cup and cone bearings you'd notice the wheel bearings are on the outside of the hub driver (end of this axle) If you look at these new sealed sets you can see the bearing is actually INBOARD of the spokes, its nearly in the center of the dang rim. The 9 is 6903 literally stands for weak as bearing. Its the least load bearing they make :( but if I was racing it is possible to do a ten minute bearing swap which is handy

Thanks for the video. I recently started hearing the knocking coming from my rear hub on my Zipp 303 disc Firecrest.

Was waiting till the end for you to say when you fitted the wheel it still had play or noise. I’ll stick with my Corima wheels

Don'd do as I did. Noticed big play in the rear bearings after only 6 moths use and removed disc and cassette to view which bearing thats was in my wheel (303s rear). As i bought them new from Bike24 and had "Life time warranty" from them and Zipp I made a warranty claim. Unfortunately the claim was turned down by Zipp/SRAM because one rubbers sealing was missing and "that had caused water to get in to the bearing". I can understand that but it was me who missed to mount it after my own little inspection, it was there when I started investing this.... my bad. So now I have to replace the bearing myself but I think I'll manage that but I would be super happy if anyone could give me the bearing/model number on all (4?) bearings needed and also where I can buy these. Great video that unfortinutely made my warranty fail, all because of me.

For what its worth I have found that the non drive side axle diameter (where the bearing sits) is slightly smaller than the drive side resulting in the non drive side bearing having a small amount of play. This is the reason for the lateral play in the wheels and not the bearings.

@Mapdec i'm considering a Zipp 303's wheelset. Looking at this known issue with the bearings would be a bit off putting. Being based in Ireland with bad weather, bearing changes are a service item. I generally do all my wheels once a year, either swapping them out of repacking with fresh grease. I can get SKF and NTN bearings relatively easily, listening to your comments here suggest that neither of the above options from NTN or SKF will give problem free solution.

Wish I'd known this before buying some 303S a few months ago. Just checked and I have 6903E LUV CW printed on the bearings

I have the newer 303s and 303 firecrest (177 and zr1 hubs) Enthralled with these issues as these are not cheap wheels, and I have other non zipp sets with zero issues over years and thousands of miles and abuse in all weather conditions. 303s rear had lateral play within 6 months- replaced with non zipp 6903 (Nachi quest) problem solved for a year now mounted on a gravel bike in dirt/ wet conditions. 303 firecrest driver bearings and wheel bearings junk (gritty internal, exterior race corroded)after 300 miles, replaced driver b’s with DT 3803, (zipp manual recommend replacing entire driver- (no thanks, people are crooks) replaced wheel bearings with non zipp (nachi quest) and all good, spin much better now. My question is why no other wheel Mfg’s seem to have this issue? I’m not even going into why the entire operation seems to also depend on that stupid little wave washer on non drive side that will flatten and break easily, causing everything to basically fail. Other sets I have are completely problem free. My thoughts after all of this is they make neat looking hoops with little golf ball dimples in them but everything else is over rated crap - look elsewhere if you want a wheel that simply does it’s job without constant maintenance and headaches

Hi there great video thank you. I’m in Australia and have a set of the 302 rim break rims…..how much should I pay for a set of genuine zipp bearings… one web site has them for crazy prices

Trek BB90 certain frames also have a problem with the Netmolded shell being slightly too big. There was a special bearing out there that was 37.1mm instead of 37. And this was the ideal fix if you had one of those frames, except that bearing is hard if not impossible to find right now. Real world cycling advises to take the bearing, outer race well cleaned, and take Teflon thread sealing tape and wrap it around the outer bearing race a few times, 3-5?, trial and error I suppose, and push into bb shell, carefully trim as needed excess. Assembled otherwise as normal. This has supposedly had good results keeping the bearing in the netmold with no play.

C3 etc refers to the internal bearing clearance (play) , i.e. between inner race, (balls) and outer race

loving the #aviodfootball films/chats.

Bit confused, have these wheels on my road bike, doesn't seem like play in bearings yet after 2000km ( hux 6903 E). Planning on putting them on gravel bike. Should I? Or will I be replacing the bearings regularly after the increase in muck, dust, moisture? Ans if so where can i get them and which ones are best? Thanks in advance

My brand new set of 303 firecrest tubeless disc only spin freely if I do not tighten de thru axle, a minimal, minimal tight in the thru axle cause it a little "sticky", is ti normal? I only ride 25 miles yet.... Thanks for to help

Beware using 'Max' bearings in wheel applications. They are intended for non-constant load, and due to maxing the number of balls, the space for lube is reduced and without that lube, the bearings will fail prematurely in a constant load application.

I have just received my new bike from Ribble with the Zipp 303s wheels and on my first ride the front wheel seems to have this problem! Strange because Ribble told me that their reason my bike took a week from being ‘built’ to being ‘dispatched’ was because of their extensive PDI checks!

Creaking video! Seriously. Have you had similar issues with Scribe wheels/bearings? Any ideas what I should replace mine with? Keep up the quality content!

Funny you spoke about direct drive trainers as my Hammer H3 has started creeking like mad and I first thought there was something wrong with my bikeframe or something

I've just fitted some 303FCs. Touch wood they are great so far after about 200 miles. It seems like every other wheel brand has problems.

Thanks for the video. My 303 FCs just arrived the other days and I've got the no serial number bearings so let's hope I'm good down the road... The only issue I have is a very odd ticking / rattling 'inside' the rims that seems to be coming from the valve side and also the opposite side on both the front and rear wheels. This is on bare wheels spun freely by hand, with no cassette or tyres fitted. Deffo not a bit of carbon burr from spoke drilling (I've got plenty of experience of that) it's not coming from the hubs (bearings) and it's not coming from the crossed spokes (again, been there many times in the past). I can also replicate the sound by lightly shaking the wheels. Anyone know if this is a peculiarity of the post 2020 Zipps? I've never heard it on any of my older 303/404 or other carbon wheels.

No markings on the bearings 🤔 that's worrying, you can't identify them.

I have had the same issue on a new pair of Zipp 303S, play in the rear axle from new. The same 6093E bearings. Two rides in, one damp ride and the non-drive side bearing was toast, dry and rusted to hell. Despite your advice I just couldn't be bothered returning them on warranty. The Zipp bearings were hardly super prescision German/Swiss bearings, but cheap as chips CW Bearings from China. Dissapointing, but at £650 for the pair they can hardly be considered anything but budget wheels, what do you expect? Once I had the over axle adapter (thanks Hambini), they were replaced in 10 minutes with genuine NTN LLB non contact sealed bearings and the wheels are utterly transformed. I will see how the LLB seals last in a UK summer, maybe LLU next time. No creaks, no play, just super magic carpet riding beauties. For the £650 paid, plus a couple of new bearings the Zipp 303's are now absolutely outstanding, performing way above the discounted price level. Do all these disc hubs have a design issue which kills the non-drive side bearing. The rotor retaining cap lets in water which sits between the cap and bearing with no where to go. Not sure even a full contact seal bearing can cope with that in a damp climate, then stored in a damp garage?

How long did it take to send to Zipp? Did you have to send to U.S.A. ? How much money did it cost to send to Zipp?

Thanks very much indeed for the follow-up. This is maddening as Zipp bearings are currently OOS for "12-14 weeks" according to the UK distributor! My go-to replacement would also be NTN 6903 bearings with the LLU seals (for mortals rather than hill climb champs), but if they squeak then what else can we try? Also have to say the "self-eating" freehubs where the external bearing is non-replaceable and likely to disintegrate is also a huge design fail! We may just have to try the NTNs anyway as folks just can't ride their bikes otherwise :/

Today I replaced my tires on my Zipp 303s, and when I was shaking the tire to spread the sealant the hub popped open and when I put it down out of suprize even some of the ratchet teeth (don't know the name of these) jumped out... is it supposed to come open this easily? Then I spend 20 minutes just to get it fitting again, whatever I tried I couldn't close it and then suddenly it just popped in, don't know what I did to make that happen even... As if I didn't have stress enough already getting those fucking tubeless tires to seal... (Vittoria Corsa Pro Control), they keep leaking so I added a bit more sealant...

Hi, within the driver body between the two 6803 bearings there is an alloy core and a very thin washer shim. Does it matter which end the shim fits inside the driver body, thanks.

Zipp/Sram service centre just told me a standard 61903 bearing will work. Now I’m really confused!

Anybody else’s 303s free hub body and cassette falling out when they take off the back wheel 🙈

Great info. I have Zipp 303s on my road bike, a friend has offered to swap(+£300 from me) his Vision Metron 45 SL as he wants the Zipp for his gravel bikepacker. He says the Vision are better for my Road bike anyway. Take deal? 😅

Heres a quick fire solution, throw the zipps away because they're meant for landfill and buy some bontrager rim brake wheels and whilst you at it why not buy a rim brake bike to match? Maybe external cables too? Like maybe an old school cadel evans canyon perhaps?? 😉😉

Would it be worth buying a set of Ceramicspeed bearings or is it too much faf?

Never touch zippwheel owned by sram are over priced very hard to get spares I have a pairwise hope hubs brilliant still working fine

A good wheel design is not critically dependent on tiny obscure details. Plus, Zipp wheels are hookless, which is just silly.

Keep the rim throw away the hubs buy some dt hubs LOL no i know these are the ones that only have a handful on miles personally if it was me id be asking for my money back

You're going to have to stop this bloke. Sharing objective helpful information learned from experience and knowing when to acknowledge other learned peers. How are you going to make money doing that? Do you need to speak to squarespace or surfshark or athletic greens or someone? Strooth! 🙂

so don't buy zipp - got it.