Tyre Width & Tyre Type Comparison

meanredspider

So I've tried to be vaguely scientific and I'm comparing

Gatorskin 25c
vs
Gatorskin 23c
vs
GP4000s 23c

For my pseudo-scientific test, I did exactly the same commute in exactly way with temperatures pretty much the same wearing the same kit on exactly the same bike. Now, it wasn't randomized in any way nor was it "blind" though I also didn't really know what to expect as a result either.

The bike is a Focus Cayo 105 with RS80 wheels. The rider was 95kg of me - 183cm - been doing this commute for 1.5 years. The route is road & path with plenty of ups and downs.

What I wanted to know was what difference tyre width and make-up would make. I ran the same target pressure F&R of 120psi - figuring that would be enough to minimise tyre pressure effects. 7 journeys on each tyre

My Garmin Forerunner 305 measured the speeds. Autopause was set to "On" and there's almost no lights on my route (which can be seen on YouTube under the same username)

Anyway - this was pseudo-scientific so no point in getting too hung up in the detail.

So the results are these - for average average speed - in rank order:

1st GP4000s 23c 18.5mph
2nd Gatorskin 25c 18.1mph
3rd Gatorskin 23c 17.6mph

The data is quite clear too. I'm now quite keen to try the GP4000s in 25c but, with crappy weather looming, I'll wait before I invest because they are a long way off the Gators' puncture resistance.

Bobbinogs

Not truly scientific (which you admit) but a very interesting test nevertheless and plenty of data to build up a decent profile, good stuff meanredspider. I reckon it confirms a lot of what I have been reading in that decent tyres do help you go a bit quicker and that 25mm is about the optimum size. Unfortunately, I can't get 25mm tyres and Cruds on any of my 3 road bikes . I still reckon that a nicer tyre helps you go quicker for two reasons: one is rolling resistance/weight, the other is the pyschological effect of enjoying the ride more. I certainly love zipping along on the gp4000s's.

As you say, would be interesting to add the 25mm gp4000s into the test but I agree that they are not really a good commuter tyre (or designed to be), particularly with the damp setting in.

cougie

Conti advise you running gp400s at about 95PSI - but good testing !

meanredspider

cadseen wrote:

Ride them on a chaingang or fast club ride, you will notice the diferrence then

I'm sure - though unless you compare them on the same bike on the same route, you'll never truly quantify the difference - or even be certain there is one (especially the 23 vs 25 question). I ride my commute pretty hard - my HR averages 80%+ and I've never been passed (not that it's busy) - I'm always looking to beat my best time - in fact I probably push too hard to be effective.

Valy

Makes me wonder why people go for 23mm - and also why pros use them - maybe because there is less give when sprinting etc?

I've been running 25mm for a while - the ride is better, the grip is better and seems people say the RR is better too - probably because of increased compliance and retention of roundness is better as per "that article" about tires on BR a while ago, though seen references to larger volume tires retaining more roundness elsewhere, but forgot!

I can't say that the RR is better as I have not done any like for like tests, however regardless of the tyre profile having effect on RR - the increased compliance surely makes a differene, to both speed and comfort!

billysan

You should try more of the same but try altering the pressures.

In my experience 25mm tires are at the best a fair bit softer than 23mm's.
I have GP4000S on one bike, run at 95/105 psi, and GP4000 in 25mm on the other, run at 85/95 psi. The 25's 'feel' so much smoother, and seem to run on a lot longer. running the 25mm's at the same pressures at the 23mm's makes them feel the most harsh oddly.

Feel is such an impossible thing to quantify unfutunately . . . .

meanredspider

Yup - I purposely kept pressures higher than either tyre might need as I've read that high pressures won't reduce rolling resistance but might increase harshness (which frankly didn't bother me). I just wanted to know which tyre was fastest (for me). 25c might work better for me than a 60kg rider. I could try to lose 20kg to see...