Not answering your speed/drag question, but two advantages of the FCs over non FCs are better stability in crosswinds and one can change a tire without using levers.

Even if drag was the same for both (which it's not), not having a bike shimmy on a fast downhill makes for a much, much better ride.

---

Team Kiwami
Instagram

FC is supposedly much stronger as well

> one can change a tire without using levers.

Do you mean just mount the tire, or can you also remove a tire without a lever?

Depends on if you are comparing clincher versions of each or tubulars. The differences for the clinchers will be much larger.

Not aware of any side by side testing of each. The extra crosswind stability benefit might mean you can run an 808 instead of a 404 though, which would be a big deal. Also, the 404 improved more than the 808 did.

So, if you are going from clincher 404 to clincher firecrest 404, I would say "big difference"

tubular 808 to tubular firecrest 808 "small difference"

hows that for science? ;)

---

---

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

http://forum.slowtwitch.com/...20firecrest;#4390784
A recent discussion that covers the topic.

Well I run tubulars now, was considering if the switch to carbon clinchers is a good idea or not.
404 front tubular
808 rear powertap tubular

savings if i switched to firecrest carbon clinchers?
savings if i upgraded to firecrest tubulars?

Yes, I can mount/demount a tire on the front and back of my FC clinchers without a tire lever.

I do carry a lever in my kit, just in case, as well as if I run into someone with a flat without FC clinchers :)

---

Team Kiwami
Instagram

I had no issues mounting the tires on my ENVE 6.7's without a lever either... I don't think I could take them off though (I haven't tried yet). The FC's were pretty easy to pull on and off.

The Zipp website claims 15 seconds faster for the 808s over 40km. They don't mention at what speed but on other testing pubs by Zipp they use 30 mph as a base line speed number over 40km for there time savings report. You will of course save more time at the slower speeds.

Zipp put together a presentation a while ago that spoke about this when the new Firecrest shapes came out. Here are a few screen shots from that presentation. The graphs in the screen shots show the time savings of the new Firecrest shape vs the old Zipp shapes over a 40k distance. The charts show that both wheels appear to be about 37-40 seconds faster than their predecessor (at their optimal point). Over an Ironman you'd be saving 4.5 times that which would be 166 - 180 seconds or 2:46 to 3:00 minutes. Here are the charts.

404


808

---

Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

So it's approx. three minutes max assuming the wind is coming from a constant 15 degrees........ which in reality is unlikely to happen? They look nice but it would be tough to justify the cost.

Yes that is best case. You could do a weighted average calculation to get a better estimate of the actual time savings.

---

Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

Any idea if that is for a clincher or tubular? The pre FC shapes are different, with the clincher being aerodynamically slower, but I've never heard by how much.

---

Styrrell

That I don't know. Sorry.

---

Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

Last year (2012) I got some 404's, and they came with the pipe valve extenders... (which no one seems to be a fan of. I use tubes with a 80mm valve instead).

This year (2013) 808's come with the valve extenders and tubes that allow you to remove the valve from the tube and place on the end of the extender. All threaded, and keeps the valve in the open where you can get to it. MUCH BETTER. Thanks, Zipp!