New farsport wheels ordered but need advice on tyres

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skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

After looking at cheaper Chinese brand wheels for a while now I've heard enough good reports to confidently make a purchase.
I had been running mavic ksyrium pro sl exalith with 25mm tyres, which are comfortable but in no way aero with the tyre really ballooning out past the rim.

The 50mm deep dish farsport wheels I just ordered are 18mm inner width and 25mm outer.
So far from my research I think the same 25mm gp 4000s II tyre that I normally use will balloon out to 27mm and 23mm of the same brand will balloon to a little over 25mm

Does anyone have any advice or experience on what tyre I should use on my new wheels? I've had good experiences with the gp 4000s II but would consider a different brand if it was a better fit.

by Weenie


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Sock3t
Posts: 447
Joined: Mon Jun 11, 2018 2:20 am

by Sock3t

You never stated your use case. Are you racing? Are you pedaling along at 12mph on a multi use path?

skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

Not racing this season but have in the past and probably will again in the future.

For now it will be 100km leisure rides at 30kph on rural public tarmac roads.

TimF
Posts: 106
Joined: Wed May 09, 2012 11:18 pm

by TimF

Do you have enough clearance on your frame or is this just a question on recommended tire width?

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

For conti maybe go with 23c in front that expands to 25mm. In the rear maybe 25c?

/a

AJS914
Posts: 5392
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I have 25mm GP4000s on the same Farsport wheels. They are great. We have rough roads around here so I appreciate an extra 2mm of volume.

So what is your concern? Either 23mm or 25mm GP4000s would work just fine as long as they fit your frame. In the end you are talking about a 1mm difference on each side of the tire. It's not a huge difference.

If you are concerned about aero, the 105% rule and all that, the 23mm tires will have a slight (like 2-3 watts) aero adantage. It doesn't sound like that is a factor for your riding.

The other option is to get a GP5000. A 25mm 5000 will be a little narrower than the 4000 and 1mm less tall.

Image

skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

No problem with clearance, my bike would probably work just fine with a 28mm tyre.

My only concern was to get the best tyre for the rim and since I need to buy new tyres anyway I figured I might as well get ones that conform to the correct airfoil shape of the rims. Of course comfort is a concern too.
That photo is very helpful though so I now know exactly how a 25mm will fit, thanks!

AJS914
Posts: 5392
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

Even though I know the tire is probably 27mm wide and the rim is 25mm, when I look at it in profile it looks to be the same width to the eye. Like I said, it's a few watts.

Get the GP5000. It's their latest tire. A 25mm GP5000 will be halfway between a 23mm and 25mm GP4000.

skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

So it would seem that gp4000 23mm with no overhang or gp5000 25mm with about 1mm overhang but probably more comfortable and my even run better over my local roads. I'd say even if I was racing it would make no real difference to speed it might make a tiny difference in a time trial.
Thanks again, it will be a few weeks before the wheels arrive, I'm sure I'll have decided by then!

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Only real width matters. Some people take comfort that it says 25 on the tire when maybe a 23 is wider. Odd.

To optimize you need rims that fit the tire width you need. If you need to go over the width of the rims you kind of bought the wrong rims.

Same goes with too wide rims. A 60kg rider on 32mm rims is also inefficient.

But as always, whatever makes you want to ride your bike is a primary goal, efficiency is secondary. We can still aim for both though. :)

skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

Well that makes sense if a tyre is labelled 23mm and inflates to 25mm width then it's really a 25.
But why would a tyre brand like continental make two tyres gp4000 and gp5000 but have one wider than the other with the same same size written on the side of the tyre?
Last edited by skyboy on Thu Mar 21, 2019 11:58 am, edited 2 times in total.

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

They just use different rims as their standard to define the width. Conti must be using a very narrow rim and vittoria a wider rim.

They are going with the times though and start to use more commonly available rims so that newer tires don't measure as wide as previous ones.

... or closer to the specified width, to be more accurate.

skyboy
Posts: 103
Joined: Wed Nov 09, 2016 11:59 pm

by skyboy

That makes sense wheels sizes have changed a lot in the last few years. However people have not got that much faster, I'm probably over thinking it especially since I don't compete.

clarinet5001
Posts: 32
Joined: Fri Jan 18, 2019 1:32 am

by clarinet5001

skyboy wrote:
Wed Mar 20, 2019 4:57 pm
No problem with clearance, my bike would probably work just fine with a 28mm tyre.

My only concern was to get the best tyre for the rim and since I need to buy new tyres anyway I figured I might as well get ones that conform to the correct airfoil shape of the rims. Of course comfort is a concern too.
That photo is very helpful though so I now know exactly how a 25mm will fit, thanks!

Well, you're looking at the '105% rule' here, right? That states you'd need a tire <23.8mm actual mounted width to get the best out of these wheels...which would include no modern tires with labeled width >21-22c...

A tire up to 24.5-25mm actual width will still work ok, but if you go above that you lose nearly all of the aero bonus you'd get over shallow rims. So 23c up front is probably max and not a 23c GP4000Sii since it likely runs >25mm on 18c internal width.

dim
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Joined: Fri Oct 13, 2017 11:25 am
Location: Cambridge UK

by dim

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by Weenie


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