Jaypkk

I bought a sweet pair of the new 303 Firecrests clinchers last fall, rode them relatively easy through the winter and began racing on them this spring. Under hard torque, sprinting or hard climbing, the rear tire strikes the frame, near the intersection of the chainstay and down tube. The Zipp website suggests that there are some frames that will be too small for the 303 and lists two frames with known issues in this regard. My frame, a Scott Addict RC, is not listed but seemingly should be, as the wider profile of the 303 is seemingly too much for the narrow Addict RC frame. I'm running a standard 23 mm tire. If I'd seen the warning on the retailer's website (it isn't and wasn't there) I might have paused and asked the right question, but I'm not sure when the 303 clincher was released that we knew then as much as we know now.

At the moment I'm feeling pinched since it looks as if I have to buy a new frame or a new rear wheel, neither of which makes me very happy. I'm hoping that the I can work something out with the retailer of the wheels, which did a free re-truing just to make sure the wheels were within factory spec but my question to the forum is whether anyone else has had a similar experience at all with the 303s and what you did about it.

FastJake

Just to be clear, is it the rim or the tire hitting the frame? Firecrest is the new wider rim, right?

Jaypkk

It is the tire, not the rim striking the frame. And yes, it is the new wider rim, which squishes the tire, makes a wider contact area, corners better, rides better and all that, but in some frames I guess is just a smidge too wide. A rear wheel from my TT bike works fine in the Addict (Reynolds 66).

I_like_cereal

It sounds as if the Addict has a flexible rear triangle. A very flexible rear triangle.
The 303
[TABLE="class: specsTable, width: 403"]
[TR="class: darkBlue"]
[TD="class: specsLeft, bgcolor: #D4DDE0"]Tire Bead Inside to Inside[/TD]
[TD="class: specsRight, bgcolor: #D4DDE0"]17.25mm[/TD]
[/TR]
[TR="class: lightBlue"]
[TD="class: specsLeft, bgcolor: #F3F6F7"]Brake Track Top[/TD]
[TD="class: specsRight, bgcolor: #F3F6F7"]25.14mm[/TD]
[/TR]
[TR="class: darkBlue"]
[TD="class: specsLeft, bgcolor: #D4DDE0"]Brake Track Bottom[/TD]
[TD="class: specsRight, bgcolor: #D4DDE0"]27.57mm[/TD]
[/TR]
[TR="class: lightBlue"]
[TD="class: specsLeft, bgcolor: #F3F6F7"]Recommended Tire Width[/TD]
[TD="class: specsRight, bgcolor: #F3F6F7"]23-32mm[/TD]
[/TR]
[/TABLE]
My Kinlin 270
13.9 mm inside
19.4 outside
10.2 brake

Those are huge. 4mm difference on the inside. It does not list the outside dimension, but it has to be just as big. Because they are so big I would guess that under torque they would flex enough to cause problems. They would probably flex more if the rear triangle is carbon.

Not much you could do there but get a new wheel or expand the rear triangle by a few mm each side.

Jaypkk

From a Zipp representative come these numbers on wheel (not tire) width and clearance required for the 303 Firecrest clinchers.
mid brake track 26.2mm @ 303mm from the axle center
max rim width 28.5mm @ 297mm from the axle center
you need 3mm on either side of clearance to be safe from possible frame flex.

I_like_cereal

To put that in perspective. You need 1/8" per side thereabout. Dang!! That's massive on a bike with tight tolerances. I'd switch the TT bike wheels for these wheels and be happy.

wesmamyke

Have you checked the bearing adjustment? It says you have been riding them for awhile, they could have loosened up. Zipp wheels also come super loose as far as bearing adjustment goes, even brand new. You are actually supposed to run them like that for less resistance, but often they are so loose they could easily cause problems like that.

Jaypkk

Good suggestion but did that immediately, thinking that a couple of recent Roubaix style races had really shaken things up. Didn't change anything. I am going to check, but I bet I have pretty close to, if not more than, 3 mm on each side, so suspect that the clearances are understated. The Zipp representative was very clear that whatever Zipp's tolerances, frame flex varies from frame to frame and of course from rider to rider. I weigh 180, well under the 225# limit on the wheels, but I'm sure someone my size and with my strength likely generates much more torque than a spindly 145-pounder does--that's just physics. So even if I'm within tolerance on the frame, I may not be in terms of torque generated.

Jaypkk

Agree on the large amount of space needed--huge! and interestingly the Zipps will not fit at all on my TT bike--just no room at the inn. I can switch easily enough for the TT wheels and cassettes, too, but it leaves me with an expensive set of paperweights, sort of. I'm going to double-check my clearances, double-check my bearings, and then talk to Scott to see what they have to say. The whole thing is sort of left field weird--it feels like something must be out of whack somehow since I seem to be a minority of one who's having the problem--seems unlikely but black swans exist. Thanks for your help.

wesmamyke

Off topic slightly but I recall a frame and wheelset issue with a Cervelo and maybe a Campy wheel? The spokes actually came into contact with the chainstay, it was hilarious, you couldn't even turn the wheel. So it's certainly possible to have a combination that just won't work.

I_like_cereal

I did some poking about on the interwebs.

I found this from another thread forum.

Jaypkk

Wow! Thanks for the research--I have not seen that thread yet so it is interesting and maybe helpful. I should have said earlier that I have a Power Tap hub in the rear--and that may be part of the issue and another part of the story. A smaller tire is a good idea, but at some point I'll be defeating the whole idea of the 303 with its wider contact area if I go with a 21 or 22 inch tire. Will look into this and report back if I have anything good to report.

I_like_cereal

My guess is that the powertap is somehow throwing the whole shebang into a tissy either through to little tension or too much.

Jaypkk

Just to catch the thread up, here's what I've done:

1. Checked the pre-load--seemed OK.
2. Checked the spoke tension--perfect
3. Tried both a 700x25 and 700x23 tire--both strike the frame.
4. Wheel is firmly in the dropouts.
5. Checked, double-checked, and switched out QR.
6. Measured the clearance on the Addict frame: 31.5 mm. (See above post about recommended clearances).
7. Tried a Reynolds 66 (with a 700x23 tire) in place of the Firecrest: no problems.
8. Tried the Firecrest in a Ti Serotta frame with 35 mm clearance. No problem.
9. Sent the rear wheel back to builder: he said he'd put in a steel axle, no charge for the labor.

Will post again after I get the wheel back. But am researching new frames--Zipp sent me a short list but said definitely I should demo the frame with the Firecrests before buying. That pretty much limits me to whatever is available in my nearby LBS.

ultraman6970

So wider is not always as good as the normal ones eh?

Jaypkk

Epilogue: Sent the rear wheel back to Wheelbuilders and they replaced the Ti (presumably) axle with a steel axle. Problem solved. Front wheel has not been a problem--no torque to bend it. Phew.

twodub

Jaypkk, I also have an Addict frame and I'm thinking about getting 303 clinchers. Replacing a steel axle in the hub eliminated all frame rub??

Jaypkk

NO. Sorry to be slow responding. I sold the bike and kept the wheels. It solved it for a while, but it came back--not as bad as with the Ti axle, but still there and quite annoying. Bought a Wilier to replace the Scott. No problems at all with frame/tire strike. Good luck. Maybe consider the new Zipp 202?

twodub

Hey, thanks a lot for the response. I would have loved the slightly more aero 303s but i think i'll eventually go for the 202s. Happy riding!

adam_mac84

I had a teammate with the same problem on his Ridley. I assume manufacturers will start making a bit wider chainstay clearance in the future if these wheels stick around.

jimc101

Wider rims / tires are the future, just like discs, unfortunately this will mean some current bikes won't be able to keep up with technology, most noticeably have been the Specialized S-Works McLaren Venge and S-Works Tarmac. https://www.zipp.com/wheels/303-firec...rbon-clincher/

Looigi

303FC clinchers? Meh. 202's are nearly as aero and 100gm lighter. 404s are significantly more aero and only 50gm heavier. (certainly there are other considerations like cross winds, etc., but still meh imo)

Incidentally, the new Roval CLX40 are 40mm deep, 23mm wide, and 20gm more than 202s (1396 gm) for $2200 list.

(factory claimed weights. caveat emptor)

Kimmo 

The answer is simple: n+1.

If you get another bike, you can just swap the wheels - hey presto.