23mm or 25mm for Zipp 808

Triathlon Forum
1

Just purchased a 2012 Zipp 808 and was wondering what people with experience would recommend?
I’m getting mixed info; some saying that the 23 is “faster” but the 25 is more comfortable and only slightly “slower”.

Any advice would be greatly appreciated

Cheers

2

Are you talking about tire width? And if so, which tire specifically?

3

Yeah sorry.

I was looking at the Continental Grand Prix 4000S II

4

23 up front. Either is fine in the rear.

5

Cheers.

Do you mind me asking why the different sizes and not both 25?

6

Same idea as the combo Continental also sells with the Attack/Force combo. Slightly thinner in the front is a smidgen more aero and the rear being a little wider isn’t really an aero disadvantage. Since it doesn’t really affect your aero, a wider rear provides a different contact patch(handling upgrade) and a bit more comfort.

Just make sure you have clearance for a 25, some of our bikes have little to no clearance.

7

Great thanks.

So if there were 25 in the front and back, that “disadvantage” would also be negligible but the ride would be more comfortable?

8

For aerodynamics the front tire matters most. For comfort and grip the back tires matters most. This is because most of your weight is over the back wheel/tire which is shielded from the wind by the frame of your bike. Your front tire is not shielded by any part of the bike and is responsible for supporting only a fraction of the down vertical stresses on the bike. In other words the marginal aero losses from increasing the front tire will only create marginal comfort gains.

9

Great 23/25 it is.

Thanks very much for all the info everyone. Much appreciated.

10

If using the gp4kII, 23c is big enough for comfort at the right pressure. That tire will measure a bit over 25mm on the FC808. Rode that specific setup and never had an issue with comfort or grip. 105lbs rear, 100 front at 170lbs.

11

Yep, and the 25mm version is more like 27mm when mounted; but then the FC rim is nearly that anyway, so I guess clearance issues should already have been accounted for.

12

That was the reason for my original inquiry. Since the 808 is 27.5mm wide I had assumed that 25mm for both was the norm.

13

have ridden both a 23 and a 25 on the rear, 25 is more comfy for sure. From other threads seem to be some ideas that the 25 is slower though.

14

Zipp recommends a 23f and 25r. As others have said, the 23 is more aero but the 25 offers better comfort. Mixing the two is the best of both worlds. I ran 23/25 on my 808s last year and it was great. Planning to do a similar setup on my 808/disc this year.

15

Thanks guys,

Unfortunately the sale fell through, no wheel for me :frowning:
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