What tyre width for Zipp 60s to maximise aero benefits

geeteewmb

Hi guys,

Just bought a set of new Zipp 60s to go on my TT bike. Looking for advice on the tyre width I should go for in order to maximise aero benefits and ensure a smooth transition between the tyre and rim.

The rim specs of the Zipp 60 are:

Brake track width = 19mm
Max rim width = 23.5mm
Internal width 13.7mm

Intend to put a pair or Conti GP 4000S on as they seem to be very well regarded as TT tyres.

I ride 25mm GP4000S on my road bike at the moment and know that they'd give me a big lightbulb on these rims. I'm worried that a 23mm would still be too wide, but 21mm would be a big drop from where I am atm, though would do it if it was the right width.

Depending on advice I might go 21mm front and 23/25mm rear as it's far less of an issue at the back.

Any advice or real world experience would be much appreciated!

Thanks

fenix

I saw this post on an american forum - abouyt 23mm vs 25mm

"No real world numbers but I had a Facebook exchange recently with someone who's in the industry and knows a thing or two about the subject. Here is their direct quote to me regarding the 23 v. 25 debate. I edited out the name of the company this person works for.

In general, we have seen very little aero difference between 23mm and 25mm wide tires on the wider rims. Any aero advantage of the 23mm would probably be negated by the lower Crr of the 25mm.

Unless the Dimond guys have seen something strange with the rear disc on their frame, I can confidently say you have zero aero penalty using a 25mm tire over a 23mm based on our front wheel testing. "

So I doubt theres much difference at all. What are your courses like ? Any bends will be easier on a wider tyre rather than the narrow ones.

nicklong

21mm's will be the worst of all the options listed. If you want to avoid the lightbulb, then go 23.

I've got wider Reynolds Assault rims and they are fine with 25s, also have Shimano C50s and they are best with 23s.