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Having had a few threads on road bike parts / tyres I’ve decided for the summer I’ll swap out my Schwalbe Luganos (came with the bike and had a years use) for something quicker. They’ve been pretty good on puncture resistance, but I’m sure they’re making the bike feel harder work than my lasts bike was.
Previous bike was a Boardman Team Carbon with mavic aksiums and rim brakes. It weighed about half a lb less than my current bike. It had Michelin Lithium 2’s on it in 23c size.
Current bike is a Cannondale caad 12 105 disc with Mason x hunt disc wheels which I believe are lighter than the aksiums on the last bike. The Luganos are in 25c size.
So looking at Conti gp4000’s - but not sure whether to gon25c or 28c. I think the rims are 19mm internal width and the frame is quoted as being ok for up to 28c tyre size but it could be quite tight around the chainstays I think.
I found a site online that shows the 28c have lower rolling resistance, but they are heavier / bigger in profile. Is there anything anywhere which suggests overall which size is better for speed and efficiency?
I mostly use the bike for commuting but am gradually extending the commute where possible to get some fitness training in to help with my mtb.
Mixture of roads and tarmac cycletrack - although there are places where the tarmac has been lifted into some biscuits ridges where roots are growing underneath it.
DANGER! Tyre sizes are the new 'manufacturer's stated weight' when it comes to brands making dodgy claims.
I got stung with my new Specialized Allez, said it had clearance for 28mm tyres so I stuck on some 28mm Contis. They actually measured 31mm across on a 17mm rim, and were far too tight for comfort.
I've had a 28mm GP4000 on a Cannondale Synapse with (I think...) 15mm rims. It worked and never seemed to rub, but the sidewalls ended up getting scuffed all the way round by *something* which I couldn't help but think was perhaps wheel flex under cornering pushing the tyre into the stay.
I reckon your 19mm rims could push those 28mm Conti GP4000s up to 32/33mm wide, and I'll bet when Cannondale 'quote' 28c on the frame, they mean a tyre which is 28mm across.
Funnily enough, the stock 25mm tyres on my Allez measured 27mm across on the stock 17mm rims.
They are my favourite tyre and I have used both 25mm and 28mm. The latter are my preference for commuting in east London including tow paths etc and also more gravelly roads (like https://photos.app.goo.gl/4D1nEa5yMwLJXvJL6 :)). On 19mm internal Alex Draw 1.9s they are around 31mm from memory.
I've used pro endurance in 25 and 28, the 28 were definitely comfier, however they felt marginally slower than the 25.
Is there anything anywhere which suggests overall which size is better for speed and efficiency
Wider = lower pressure = more comfort.
Increase in weight and decrease in RR are tiny. Rim width irrelevant at road pressures too.
Interesting. I’ll get the tape measure out and see how wide the chain stays are at the closest points to the current tyre. If a tyre blows up to 31mm I very much doubt that’s going to fit so may have to go 25c on the gp4000s.
DANGER! Tyre sizes are the new ‘manufacturer’s stated weight’ when it comes to brands making dodgy claims.
I got stung with my new Specialized Allez, said it had clearance for 28mm tyres so I stuck on some 28mm Contis. They actually measured 31mm across on a 17mm rim, and were far too tight for comfort.
Interesting. I’ll get the tape measure out and see how wide the chain stays are at the closest points to the current tyre. If a tyre blows up to 31mm I very much doubt that’s going to fit so may have to go 25c on the gp4000s.
Conti are a nightmare for quality control when it comes to size on their road bike tyres. I've seen 25c GP4000's that measured 25mm, I've seen the same 25c tyre on a similar rim measure 28mm! Doesn't surprise me that you've seen 28's come up as 31mm...
Schwalbe are a lot more predictable, usually within 2-3% of their stated size, so a 25c Schwalbe usually comes up between 25-26mm on a "normal" 17mm internal rim say.
If you are more interested in reduced aero drag, go 23mm up front (that will measure near 25mm) and a 25mm on the rear 9tht will measure near 27mm).
Or try the new GP5000s, which appear to conform to size much better.
28mm GP4000s are massive. The GP5000 28mm come up closer to 28mm. I think they've recalibrated their ruler.
I've used schwalbe ones in 25s and 28s and couldn't tell the difference in speed or comfort.
Going from 23s to 25s was a massive improvement.
Sounding like the 28c are going to be too big. 25cs sound the better option my the caad 12....if they come up say 27mm that sounds perfect.
I have 25c and 28c Continental 4000s ii on bikes at the moment.
My observations:
The 28s are like ‘monster truck tyres’I don’t have a calibrator so can’t measure either tyre.
The 28s are comfy, look at bit too big and are definitely slower than the 25s.
When the 28s wear out I will replace with 25s even though they are on my winter bike.
I am 85kg.
Will get some 25’s ordered in the next month then - thanks for all the comments!
I have been bitten by this too.
Had 27mm tyres changed to 28mm GP4000's, had to McGuyver the front mech for clearance and on a set of prime wheels came up as 31mm when I measured them. Two other bikes already on 25mm GP4000 (one on a set of Hunts) wouldn't fit the 28's at all!
25 might be the safer option to ensure clearance ?
definitely slower than the 25s.
Science states otherwise!
On that last point the 28’s appear to have better rolling resistance figures, but does the added weight and aero profile blunt that benefit at all? I’ve no idea on this stuff and I’m no Bradley wiggins so at best will probably average about 20mph on my normal sort of ride I’d guess.
I think 25’s are the way forward as 28’s are unlikely to fit.
Having used the 23s, 25s and 28s for years, I'd say that it's really a case of matching them to how rough your roads are. Round here they're often in a poor state, and when they're repaired it's normally a tar-and-chip job, so 28s roll over that more easily. On nice smooth continental tarmac the 23s are sweet. I'm highly sceptical of the usefulness of simplistic lab tests of rolling resistance.
By the sounds of it, though, 25 is probably the right choice for a CAAD (I used the 23s on my CAAD9 and I think the 25s would have run pretty tight, and that was on 17mm rims—though obviously a 9 isn't a 12). At the end of the day all three ride very nicely, I wouldn't obsess over the difference.
If they fit, I'd suggest 28s. I use 28mm 4000S II tyres for longer distance road riding, and they roll very nicely. I don't think the small aero advantage of 25s would offset the better rolling resistance and comfort of the larger tyre.
Cynic-Al (sorry I can’t seem to do the quote thing).
Science may well say otherwise but my legs tend to give me decent feedback so I’ll go with that. 🙂
I agree with four. I have a Canyon Ultimate SL and always, always ride GP 4000sII's in 25.
But for Flanders RVV last year I bought some 28's.
They are nice and comfy but in my opinion the weight/rolling resistance difference is noticeably more for the 28's.
We should all know by now that science, like statistics can be used to prove whatever you want to prove.
Personally I'd go for 28s every time, unless racing. The difference in terms of speed is negligible. But they feel more comfortable and offer better stability, especially on cracked and broken roads. They're more suited to everyday riding. If the bike will accommodate them of course.
As for rolling resistance, that's only part of it. Aerodynamics and weight are critical factors. So whilst a larger tyre may have better rolling resistance, they can still have increased drag. Which is why I'd opt for a 25 racing, it will be faster. Just for me, and I think most people, the difference is so small, it's not worth the trade.
Just looking at tyre choices for the summer.
Bike is Tripster AT
Rims are Fulcrum 622 x 19.
Tyre choice is going to be Continental Supersport Plus. Had good results with these in the past on the grit covered local lanes, resistance to P*******s etc.
But what size?
x 25 are £29.95 (£59.90 pair)at Halfrauds.
x 28 are £16.95 (£33.90 pair) at Halfrauds.
£26 difference. Tempted for x 28 for that little bit of extra comfort, and the £26 saving!
What is the bike going to roll like with x 28's?
I hope significantly better on tarmac than the original Vee Tire T-CX x 40
That seems like a no-brainer, surely? Enjoy your £26.
science, like statistics can be used to prove whatever you want to prove
Erm, no, they are completely different.
First ride on the Conti’s (went 25c as 28c would have been very tight if they are as over sized as people suggest) this morning and got a pb on a very pedally bit.
The bike feels that bit quicker and whippier - although the weather was also beautiful and I’d remove the winter mudguards so they could be some feel good factor there too. As long as I don’t get huge numbers of punctures I’m really pleased with the choice.
Cheers all.
Edit - just saw your final post. I think you probably did the right thing
Others have alluded to it, but the 28s do come up big - only a whisker smaller than my Schwalbe marathon 35c's. They're one of the few tyres I've heard of coming up oversize (typically manufacturers make them smaller so that if you compare the weight of their 25 or 28 against a competitor it comes out looking lighter).
In the real world, both sizes are a good tyre.
science, like statistics can be used to prove whatever you want to prove
Erm, no, they are completely different.
People have had enough of so called experts!
Which is faster and more efficient?
If only there was a test group of riders who rode really long distances at speed and were backed up by teams of technical experts with a choice of tyres at hand.
Most pro riders (cobbled classics aside) ride with 25mm tyres. That's your answer.
Yeah but pros will be riding tubs so not a direct comparison.
Science states otherwise!
Science states, at the same pressure a 28mm has lower rolling resistance compared to an equivalent 25mm tyre. That's not the same as science stating it's faster. There are also weight and aero to add to the equation.
23's are noticeably faster than 25s on the front as they develop a better laminar flow around the wheel - so much so that it eclipses the rolling resistance gains.
23 front 25 back is the quickest, unless you have a frame built for 28 rear like the 3t Strada then 23/28 is correct.
Then again, if you're only training or riding casually I would stick to 28/28.
Most pro riders (cobbled classics aside) ride with 25mm tyres. That’s your answer.
Well not quite...most pro riders are sub 80kg's unlike most keen amateur and recreational riders and are after out and out performance and not really factoring in comfort, so not really a valid comparison....most pro-riders also ride frame sizes far smaller than intended for their height so they can slam their ridiculously long stems and so they can get into more extreme riding positions for aero gains that most of us couldn't tolerate for more than 5 minutes, but we don't all mimick that. Pro riders are also extremely vain and will ride kit that just looks cool or is the next cool thing amongst the peleton, so they're just as tarty as the rest of us.
I've ridden both the 25mm and 28mm versions of the tyre on different bikes though so not a back to back...to be fair I ran them both at the same tyre pressure and i'm dammed if I can notice a difference between the two. I'm currently running the 28's and recently (literally for the last two rides) dropped the pressures by 10psi, and again not noticed any difference...i guess marginally more comfy, but certainly don't feel any faster...but having said that got quite a few PB's on strava segments on my last ride...but i am getting fitter too. Personally I prefer the 28's...they just give me more confidence under braking and cornering, but that's just a mental/placebo thing. So as long as i don't notice a difference in the sluggishness of the tyre then i'll stick with 28's.
Well not quite…most pro riders are sub 80kg’s unlike most keen amateur and recreational riders and are after out and out performance and not really factoring in comfort, so not really a valid comparison
To be fair the op is asking which is better for speed and efficiency. He\she isn't asking which is more comfortable.
Fair point. I found the 25’s this morning fine for comfort - running 100psi rear / 90psi front. Ymhere are some harsh ridges on the cycle track where the tarmac has lifted with roots growing underneath - but only in one 100m stretch. The rest of it is pretty smooth.
New tyres are definitely faster than the old ones which is the main thing!
Joebristol, I'd be tempted to experiment with those pressures, I'm probably 92kg with riding gear, commuting rucsac etc. and currently enjoying my GP4seasons at 70psi front and back on a 17mm internal DT R460 rim.
They probably have slightly chunkier sidewalls than the GP4000 but if you're a similar weight I'd bet you could try lower.
Hi,
I bought some 4000's in 28c last summer. Loved the extra cushion coming from 25c schwalbe lugano's.
However the 28's don't fit with mudguards on so have gone to 4000's in 25c.
The 25c are much harsher.
@joebristol if you are
gradually extending the commute where possible to get some fitness training in
then do you really want to have the most efficient, lowest rolling resistance option? Stick some Marathon+ tyres on there to get yourself fit.
Peekay- I know what you’re saying but I also want the bike to feel nice to encourage me to extend rides further. Plus often good training is pushing yourself against other people on the cycle track - and I’m currently not winning in fitness terms but need to stay in touch to get the benefit.
I’m around 80kgs ish and want to lose about half a stone (sorry to mix scales) so I’m also tying to run /
Cross train / not eat so much bad FOD.
Pro riders are also extremely vain and will ride kit that just looks cool or is the next cool thing amongst the peleton
Pro riders are doing a job, and they use the kit that they are paid to use. Occasionally someone will choose their own stuff and get it rebadged to look like their sponsor's product, but most of the time they ride what they are given.