Conti GP 5000 35C: a new standard for road frames?

[Da11as]

This is reflected in the tread width and the casing construction.

Exactly this. You don't want to ride on the tires that baloon waaay too much, unless you want to ride on sidewalls... Which will be fast, but not for too long.

[jeanpierrebalsac]

I do know know how it is with the 32mm tire on 32mm into rims, but for my 36 on 32 I will never reach the side wall. Even in an extremely leaned position where my pedal already touches the ground at 45 degrees from the bottom position, we are still comfortably on the thready bit of the tire.

[Serge_K]

Exactly this. You don't want to ride on the tires that baloon waaay too much, unless you want to ride on sidewalls... Which will be fast, but not for too long.

I dont think anyone will ever disagree w that, but it's a question of quantifying it / at which point does it matter, and also, how aggressive is the rider with cornering?
I have 32C measuring 34.4mm, there's zero issue. Also, when my rear tyre gets old, the middle of the tyre gets flat, because most of my riding is on the flat, little cornering.
Would a 35C measuring 38mm be pushing your luck? idk, but somehow i doubt it.
I do remember that bicycle rolling resistance noted that the fast Michelin road tyre in 28 i think it was, had a very narrow usable thread, with more sidewalls than competitors. So a tyre like that, you'd want to be careful with.
But i've never heard such issue w Conti GP5000.

[Sakizashi]

I'm running 36mm tires on 32mm internal rims. At first I was apprehensive about it as well. Then after running it for a couple of months and liking it, I also saw on the Nero show's Dog or fast bike section that someone with a Canyon Aeroad was running 32mm tires on 32mm internal rims which blow up to 36mm (Nero show on March the 4th, at: 1:07:45) and racing them.

I'm sure the ETRTO have some reasons for not allowing this and thus officially one cannot recommend it. However, I am personally fine running it.

At the very least, you should consider it a proper guideline for use. It's great that a bunch of influencers don't notice or care about safety either, but the consequence is shredding your sidewall (light) or dismounting your tire and crashing (severe). Why would you recommend doing something so stupid?

The risk obviously wouldn't be the same between a 36mm tire and a 32mm tire on a 32mm IW rim, but it's still well outside the tire's design unless otherwise specified. Does it really hurt to read the packaging or documentation before installing a tire? Remember that while it has its flaws, the ETRTO is an engineering standards body. Of course, people on the internet categorically know better than a group like them, right?

I dont think anyone will ever disagree w that, but it's a question of quantifying it / at which point does it matter, and also, how aggressive is the rider with cornering?

Remember that tires are not static under cornering loads, and the ground isn't always perfectly flat. Besides, sidewalls are only part of it. The other part is how the tire ends up being shaped and how that affects the different materials that are laid out in the casing. At the end of the day, it's sort of your risk until you crash someone out or damage someone else's property, but the important thing here is that this isn't just about how much the tire measures vs. marked. The size chart and the marking on the sidewall are part of the same compliance scheme, so if the ETRTO size is something, it corresponds to that size in their safety chart.

[Takiyaki]

I'm running 36mm tires on 32mm internal rims. At first I was apprehensive about it as well. Then after running it for a couple of months and liking it, I also saw on the Nero show's Dog or fast bike section that someone with a Canyon Aeroad was running 32mm tires on 32mm internal rims which blow up to 36mm (Nero show on March the 4th, at: 1:07:45) and racing them.

I'm sure the ETRTO have some reasons for not allowing this and thus officially one cannot recommend it. However, I am personally fine running it.

I think it's super dependent on use case as well. The more time you spend on the side of the tire the less room you have to deviate from ETRTO/manufacturer recs. I basically ride straight up and down like 99% of the time so I feel OK getting a little more aggressive with tire/rim combos for efficiency and comfort.

[Da11as]

I dont think anyone will ever disagree w that, but it's a question of quantifying it / at which point does it matter, and also, how aggressive is the rider with cornering?
I have 32C measuring 34.4mm, there's zero issue. Also, when my rear tyre gets old, the middle of the tyre gets flat, because most of my riding is on the flat, little cornering.
Would a 35C measuring 38mm be pushing your luck? idk, but somehow i doubt it.
I do remember that bicycle rolling resistance noted that the fast Michelin road tyre in 28 i think it was, had a very narrow usable thread, with more sidewalls than competitors. So a tyre like that, you'd want to be careful with.
But i've never heard such issue w Conti GP5000.

Few years ago, new Corsa Speed were introduced in size 30c and Jumbo Visma Switched onto it, around the same time they got new super wide Reserves. It was very fast, however, on that particular season, they got punctures on every race. BRR tested these tires, they figured the thread width remained the same as on 28c. Consequently, they rode on the sidewalls of already thin tire which ballooned beyond its expected width. It is very similar situation when a person is trying to fit relatively narrow tire on a very wide IW rim. So yeah, it is very likely to happen with high performance tires when one is chasing weight reduction and/or 105%.

[biceryder]

Good debate here and honestly when I mounted my 40c Pirelli’s to Tagoola Aero Raptors I never even thought about tire compatibility… something I would have completely looked at for my road bike.

Only a few rides in and now I am looking at how the tire is wearing when I corner.  I’m not super aggressive but I have some chicanes on one of my routes that I like to test my abilities on.

Regarding the 32IW, the Tagoolas are hooked, which gives me some small modicum of confidence.

[Sakizashi]

I mean people shouldn’t be treating reference standards like this as a debate. There is a clearly wrong answer. A member of ETRTO is agreeing to design at least to spec. So if it’s not otherwise specified, a marked 40mm tire is designed for at most a 27mm IW rim. Likewise a marked 29mm tire is the smallest size generally designed for use on at most a 25mm IW rim. Assuming that a manufacturer designed the tire for a wider rim, but isn’t claiming the benefit seems unwise.

Unless you are using a tire that is claiming expanded compatibility with wider rims (e.g., the Goodyear / Zipp tires), breaking the rules means you are willingly eating into the margin of safety that is part of the design process around that tire. Obviously using a tire outside of spec only affects the risk of failure—as failure is based on probability in expected use, not a binary thing. Understanding that you are making a conscious decision to eat into the safety factor of your setup should be something at the top of your mind when you make the choice to run these ultra-wide rims for road or gravel use.

A tire hook—probably doesnt do much to lower the risk of failure caused by too small a tire since that helps more with local separation of the bead from the wheel, but IDK I am not a fan of hookless either. One thing I can’t square is the hypocrisy of claiming hookless is dangerous, but using tires outside their designed IW compatibility isn’t.

[jeanpierrebalsac]

As you understood by now, I am not as concered about it as you. But I do understand your point of view. And I like big rims and I cannot lie.

Therefore, the best solution would be (and probably will be) rims like the Duke WRX AERO 42. On the 28 internal, a 40mm (like the Michelin Pro 5) tire will probably blow up to a 43 or so, making is perfectly in line with the rim and being within ETRTO standards. Everyone happy! It will just take some time for the bike industry to adjust.

[Pistonbroke]

Tried a 35mm gp5k this morning on one of Peter's 26mm wheels.
Had it on the back. Fast and comfortable, really comfortable. Currently 38mm wam.

[Rolle2k]

Kinda would like this U-shaped design, but with 26mm or max 27mm IW and then about 38mm OW at the widest part of the rim.
https://www.aliexpress.com/item/1005012068359058.html

[zett]

As usual the bike industry is overshooting. Wide tires are good (to a certain point), but of course there is no free lunch. I don't expect 35 mm tires to become common on road bikes. The sweet spot is somewhere between 28 and 32 mm, depending on riding style on road conditions.

I've recently switched from 28 to 32 mm tires on an endurance bike. The new tires run wide (WAM ~34 mm) and I definitely feel how this effects handling and acceleration. Also, while it is more comfortable, it is not like this is a groundbreaking change compared to 28 mm. And yes, I've experimented with tire pressure and made sure it's not too high.

I have also switched from 28 mm to 30 mm on a race geo bike. The difference is minimal, not really worth it.

[Leo.D]

It's a worst-case safety net, not a performance guide. Written to prevent tire blow-off under a heavy rider on a hookless rim at max pressure with tolerance stacking. If you know your rim and your tire's actual mounted width, you can make your own call. The rule of 105 was always a heuristic, not a law.

[jeanpierrebalsac]

Tried a 35mm gp5k this morning on one of Peter's 26mm wheels.
Had it on the back. Fast and comfortable, really comfortable. Currently 38mm wam.

Cool, I added this info to the https://rubbersideup.cc/ database.

[OralMaster]

thanks to my 20/20 vision, riding an enve melee that takes up to 35c tires. this will be my end game road bike.

if you guys are looking for lightweight 35c tires (not BRR tested) that weights 280g, look up IRC jetty plus 35c. They roll ridiculously well I was even dropping people right and left on viaducts and climbs.