If tubeless is not an option for you, and you can't squeeze in a 25, there is nothing wrong with what you propose.

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Definitely do latex. That's about the cheapest speed you can buy. GP5000s are a solid option, I personally prefer the Corsa. But you can't go wrong either way

There are lots of faster options, but I'm not going to comment on those since I haven't been using them and would just be basing my comments on the same daat you've looked at. However, I currently use GP5000 tyres and Vittoria latex tubes (25mm size mounted on 19.5mm inner width rims) and I'm very happy with that setup. There's no reason to use a different setup for training unless you're worried wear on the crown of the tread will damage your aerodynamics. I use the same for training and racing, life's too short to use a less enjoyable setup for no reason. I check my pressure before rides anyway, whether butyl or latex tubes. It's of no consequence that I might need to add a couple of strokes of air to compensate for losses with latex. Changing tyres back to an alternative training setup after events is far more inconvenient than adding a bit of air before rides.

Your choices are exactly what I would do.

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Really curious what those faster options are (given it needs to be 23c, clincher, quite puncture proof and not super expensive).

Also, for a race I don't mind putting in some air, but for training I do mind since I don't like time consuming stuff. My disc has the hole covered, which is annoying when you need to pump before every ride (even with butyl I need to pump once every few rides).

Also I think new tires make sense before a race. Both because of aeroness and rolling resistance, but also because of puncture protection. I tire that has had 2000 kilometers of riding has a bigger change of a flat than a new tire. Since the tire moves down to my other bikes, it's no problem. Also, I only do 2 big races, so it mean 2 new sets of tires. That's not that bad, since after a race they stay on for about 2500km of training (that is about the interval between races).

Only other thing I would need to check if I can fit 25c on my older rims and have enough clearance in the back. Rim is a Fulcrum Red Wind 80mm (20,5mm witdth). Not sure if that is faster than a 23c (roads a good quality, comfort not really an issue).

Thanks, Corsa is on my list as well (on road I also use Schwalbe One). Couldn't find a reaseon to choose Corsa (or Schwalbe) over GP5000. Why do you prefer Corsa?

Personal experience, but I’ve had a ton of flats with GP5000s. Plus they’re a pain in the ass to mount. The corsas have been a bit faster in my testing too

Apologies, I was unclear. The faster options I'm aware of all likely sacrifice robustness for lower rolling resistance. There's no free lunch. For my priorities which are similar to many people's, including you (aside from the raceday swap), GP5000 seems like the best option. If I was changing for raceday, I might consider a faster option at the expense of some robustness, but using it for training makes GP5000 the choice.

I also don't like time consuming stuff, but that's why I don't swap out tyres and tubes for events. Maybe the disc is hassle, but otherwise top ups for latex really is a non issue for me. If I was you, and I'd probably consider getting a non-disc training wheel and keep the training setup on that, and the race setup on the disc. Even less hassle.[/quote]
My evaluation would differ from yours here. Aerodynamics may be better with a new tyre, but rolling resistance may be better on the older one. As for reliability, I'd take a tyre with 2000km that hadn't been off the rim recently in preference to a newly installed brand new tyre any day. I would definitely expect a bigger chance of a flat with the new tyre unless the old one has visible damage. New tyres have the added risk of poor installation (e.g. pinched tube or badly positioned rim tape), and the possibility of a manufacturing fault or accidentally leaving a bit of debris inside the tyre. Similarly a new tube could have a manufacturing defect like a pin hole or a leaky valve. Rare but possible. By contrast a tyre that's already lasted 2000km will likely be fine for another race distance, if not another 2000km (well the front anyway!)

Regarding 23c... what does the c stand for?

I use rim brake Zipp Firecrest 404s and 808s from the mid-2010s on a BMC Timemachine from the same era. I went through the same evaluation as you and came to the same conclusion: GP5000 with latex tubes. I use a 23mm on the front and 25mm on the back to try and get the best combination of aerodynamics, rolling resistance and comfort. I was pretty set on 25s on both ends until someone mentioned Josh Poertner's "rule of 105". https://blog.silca.cc/...ure-and-aerodynamics

My evaluation would differ from yours here. Aerodynamics may be better with a new tyre, but rolling resistance may be better on the older one. As for reliability, I'd take a tyre with 2000km that hadn't been off the rim recently in preference to a newly installed brand new tyre any day. I would definitely expect a bigger chance of a flat with the new tyre unless the old one has visible damage. New tyres have the added risk of poor installation (e.g. pinched tube or badly positioned rim tape), and the possibility of a manufacturing fault or accidentally leaving a bit of debris inside the tyre. Similarly a new tube could have a manufacturing defect like a pin hole or a leaky valve. Rare but possible. By contrast a tyre that's already lasted 2000km will likely be fine for another race distance, if not another 2000km (well the front anyway!)[/quote]
Thanks for your reply. I'll see if I can live with pumping before every (training)ride. Might keep the latex inners in that case.

On the new/old tire I'm not convinced. I agree that a new tire has some risks. That's why I put it on about 2 (maybe 3) weeks before the race. I will get some miles on it to be sure it's not a flawed tire (and to make sure the inner tire sits correct within the tire).

As far as getting a training rear wheel. I actually have one (to fit my front wheel). My bike however has the worst nightmare brakes in the universe (TRP aero crap) and it's almost impossible to adjust the brakes to different wheels. It's also impossible to get a wheel in/out without totally deflating it. It's the only reason I ride my disc for training as well (and sometimes I commute my 35km ride to work with a disc wheel and I backpack, which must look hillarious) :)

Thnx for the link. Missed that one. Also deals with old versus new tires. Great info and back up my theory that my 23mm tires are not that bad or a choice for my triathlon bike (although my rims could be better/wider).

Than the next question. How much bar should I run in mij 23mm wheels. I normally go with 7,5 bar if road a in a good condition. I'm 72 kilo and don't care a lot about comfort (although 8bar feels quite 'bumpy'). Is 7,5 a good starting point, or is there a reason to always go lower (which logically seems to be the trend with wider tires)...

Silca has a pressure calculator
https://silca.cc/pages/sppc-form


I'm running a mix of 23 GP5000 on the front and a rear GPTT on an older "mid-width" wheelset since the TT is slightly faster rolling and the rear shouldn't impact aerodynamics as much. On Race wheels only since I don't trust the TT as a daily driver. If I were going for one tire for all the time, you can't really get any better than the GP5000.

I too recommend and use the Silca tire pressure calculator.

After seeing and reading about the shift to wider tires — and the lower pressures that everyone seemed to be using — I expected the calculator to propose a much lower pressure for me. Instead, it said 90-95 for 25mm and 100-105 for 23mm. So, don’t be surprised if it doesn’t suggest a significantly lower tire pressure.

I should also reiterate what someone mentioned above: Make sure the tires fit your frame. Thankfully, the BMC has horizontal dropouts on the back. But a 25mm front tire comes eerily close rubbing on the frame. I was glad to settle on a 23mm front tire.

For those of you running different F/R tire sizes, AND manually adding a wheel sensor diameter (as opposed to letting GPS calculate it): how do you account for the different circumferences? Split the difference between, say, 2096 (700x23) and 2105 (700x25)?

The wheel sensor is only 'interested' in the circumference of that wheel (obv). If you have a F=23 and a R=25, your front wheel will go round faster: how cool is that?

I've been racing on 23mm vitoria corsas with latex tubes for a decade now. I have put some GP5000 on my road bike and really didn't like them - the profile is different to the vittorias and specialized tyres I normally use - and that may jsut be a 'get used to it thing' but 3000km and still finding them slightly more 'squirmy'.

The corsa's do cut up pretty quickly on the rough chipseal I ride on, but then that's also where the speed/feel comes from compared to the more resilient alternate rubber. They are raceday / final training ride only tyres. That said, I have then used old 'A' raceday tyres for many subsequent club races/rides with no issues, so I think it's more that they look like they've been in a fight with edward scissorhands and won, more that they actually are that fragile. Mount pretty easily too.

Re the tubes, then I've used Michelin and Vittoria, and aside from one being green and one pink I can't say I notice any difference (although both way better feel/speed than butyl). Equally neither lost all that much air overnight. Still would top up in the AM though, but never an issue riding home after the race is all done.

Regarding needing something cheap and punctureproof - changing tyres for race is to me a positive thing. A good part of mental prep and getting my 'race face on'. It's 20mins tops and is the chance to check through the bike at same time whilst you're in taper mode anyway. So a good mindful task. New bike is tubeless, and that's a totally different kettle of fish though, I'm still trying to process that one, but not a discussion for this thread ;-)