Carbon rims and low tyre pressures for commuting?

Winno

Likes Dirt
Hi peeps.
I have a Trek Procaliber 9.8SL hardtail which runs Maxxis Ardent Race 2.2 tyres on Kovee Elite 23 Boost carbon rims.

357928


I'm looking to switch off the Maxxis for some Bonty R3 32mm road tyres when I start commuting.
Trouble is, Trek tell me I really shouldn't be running more than 50psi on these rims given their wider width and being carbon.
After previously running 100psi on my old road bike and mountain bikes (narrow aluminium rims) 50psi seems way low.
I love speed and traditionally higher pressures but don't want to wreck my nice wheels.
I also don't want to buy a second set of wheels because it would be costly as I'd need to run Boost hubs and lace them to higher capacity Al rims.

I'd welcome any comments re running low pressures for commuting.
Does it work?

Cheers all.
 

hifiandmtb

Sphincter beanie
Use a wide smooth-treaded commuter tyre that’s happy at less than 50psi.

Something 40c or fatter would work.

Efficient & super comfortable.

I run Specialized Sawtooth tyres...



Running any tyre over 50psi on a non-road bike is silly.
 

Flow-Rider

Burner
It's obvious your bike shop has seen rims split with overly high pressures and possible not the brand rim you have but they've warned you about. I don't think I would risk splitting carbon rims either with running a high pressure.

It's easier and simpler buying a cheap bike for commuting duties, otherwise everything just becomes more of a compromise between road and bush.
 
Last edited:

Winno

Likes Dirt
It's obvious your bike shop has seen rims split with overly high pressures and possible not the brand rim you have but they've warned you about. I don't think I would risk splitting carbon rims either with running a high pressure.

It's easier and simpler buying a cheap bike for commuting duties, otherwise everything just becomes more of a compromise between road and bush.
I agree. I don't want to risk it either.
One thing I have noticed after a bit of reading this morning is that there seems to be a general trend to running fatter tyres and lower pressures on the road.
Last time I had a road bike things were heading the opposite way and I was running 120psi and 25mm.
 

creaky

XMAS Plumper
I run 33C tyres on my commuter bike on 21mm internal light alloy rims.
I weigh 82kgs an run 55 to 60psi rear. Wouldn't want to go much lower than that personally. 50psi would be too low IMO.
 

Flow-Rider

Burner
I agree. I don't want to risk it either.
One thing I have noticed after a bit of reading this morning is that there seems to be a general trend to running fatter tyres and lower pressures on the road.
Last time I had a road bike things were heading the opposite way and I was running 120psi and 25mm.
Yeah, I think the gap between road and mtb bike design is getting bigger by the years, I've run 26" 19mm ID Maddax rims with MTB slicks at 60~80psi too. With the MTB new generation rims things have changed, light weight and minimal material used, the wider rim will provide more leverage on the rim bed so really not a good combination for the higher pressures.
 

hifiandmtb

Sphincter beanie
I run 33C tyres on my commuter bike on 21mm internal light alloy rims.
I weigh 82kgs an run 55 to 60psi rear. Wouldn't want to go much lower than that personally. 50psi would be too low IMO.
Run bigger tyres at lower pressures.
 

ozzybmx

call me Cáitín
Before I sold my roadie, I was running 28c tubeless at 70psi, 32c would be lower but not 50psi.

40psi on my CX with 40c Schwalbe G-ones.
 

hifiandmtb

Sphincter beanie
Because lovely!

As stated earlier, quality 40c-ish road tyres are bloody brilliant!

Mate's Ibis Hakka on big tyres is brilliant. Mate's Baum on big tyres is awesome. Even my mutt (above) on 42c's is waaaaaaay nicer than running on the Conti 32c's it was on previously.
 

Daniel Hale

She fid, he fid, I fidn't
Why? Heavier and slower?
It’s road and concrete path.
yes but it’s more comfortable...i don’t think carbon will split like alloy rims, have some stan’s gold, which are supposed to be keptunder 35psi, they take 50 no worries, you can get away with 50-60 psi on 28-32c rubber, much smoother than 25c anyway..100psi is for wane be road rats
 

bear the bear

Is a real bear
Hi peeps.
I have a Trek Procaliber 9.8SL hardtail which runs Maxxis Ardent Race 2.2 tyres on Kovee Elite 23 Boost carbon rims.

View attachment 357928

I'm looking to switch off the Maxxis for some Bonty R3 32mm road tyres when I start commuting.
Trouble is, Trek tell me I really shouldn't be running more than 50psi on these rims given their wider width and being carbon.
After previously running 100psi on my old road bike and mountain bikes (narrow aluminium rims) 50psi seems way low.
I love speed and traditionally higher pressures but don't want to wreck my nice wheels.
I also don't want to buy a second set of wheels because it would be costly as I'd need to run Boost hubs and lace them to higher capacity Al rims.

I'd welcome any comments re running low pressures for commuting.
Does it work?

Cheers all.
They are a MTB rim and hence the 50psi rating which is the recommendation for use with MTB tires. The risk with too high a pressure is the potential for the tire to blow off the rim during use rather than the rim itself failing.
As tire size decreases, pressure can increase.
With a proposed 32mm tire you should aim for 60-70psi.
 

creaky

XMAS Plumper
They are a MTB rim and hence the 50psi rating which is the recommendation for use with MTB tires. The risk with too high a pressure is the potential for the tire to blow off the rim during use rather than the rim itself failing.
As tire size decreases, pressure can increase.
With a proposed 32mm tire you should aim for 60-70psi.
I’ll back this up by saying that a set of stans grail rims I have specify different max pressure ratings for various tyre sizes (mtb tyres Size is 40psi and up to 100psi for a 25c, from memory)
 

Cardy George

Piercing rural members since 1981
Hi peeps.
I have a Trek Procaliber 9.8SL hardtail which runs Maxxis Ardent Race 2.2 tyres on Kovee Elite 23 Boost carbon rims.
First up, I applaud your choice of steed! Mine runs the DT Swiss XMC 1200 Carbon Rims. 14,000km and not 1 drama.

To answer your question, yes it does work, but tyre choice is everything.

My commute is 60/40 road/loose over hard and the Gold Standard for me is Vittoria Barzo (f) / Mezcal (r) at 2.35" wide with pressures around 25/35 for commuting, as I carry a bit of weight some days. The only problem is they're a bit exxcy for burning up on a commute.

Right now I have an ancient 2.2" Conti Trail King on the front, and I'm experimenting with a 2.25" Onza Canis on the back. On a sample size of one ride to work, it's got a good feel to it. Should prove pretty quick on a proper day.

If you still wants knobs the key to it is having the center knobs closely spaced, or if there's no dirt involved, find a good mtb sized slick.
 

Winno

Likes Dirt
These are all great responses guys.
Thanks.

My LBS has kindly offered to let me fit a pair of 32mm Bontrager R3 to my rims to see how they go. I think they're wanting to see for their own interest as well.
I've had my Maxxis Ardent Race 2.2 tyres up to 45psi and that was plenty hard (bigger volume I know). The shop is also recommending the Maxxis Refuse which I tried once before but didn't like for some reason. That was a while ago so I can't remember specifically why.

My rims to have good bead seats so I don't think having tyres blow off will be an issue. I'll be going back to tubes to allow for easier/cheaper tyre swaps for weekend rides in the forrest.

In the end though and if it doesn't work, I may just have to find a nice road bike.
 

leitch

Feelin' a bit rrranty
I run 38c Panaracer GravelKing slicks on my CX bike for commuting, at 45-50psi. They're fast and comfortable. Lower pressures does not necessarily = slower (and you'll always run lower pressures in larger volume tyres).

For convenience sake the best bet is just get a cheap 2nd hand pair of alu wheels and set them up with the commuter tyres.
 

silentbutdeadly

has some good things to say
I run Pirelli 4S 28mm road tyres on the generic aluminium rims that Giant used to call PCX-2. They used to be fitted to the Anthem and some other Giant XC bikes. They also came with a max pressure warning of 50 psi (from memory). I've run them as hard as 80 psi but typically around 60. I've been doing that for the last four years...
 

The Duckmeister

Has stumpy thumbs, Speciaized are so weird
Pressure is very closely related to tyre volume - a bigger tyre will need less pressure to attain a givven level of firmness than a small-volume tyre. Similarly, the width of the tyre vs the width of the rim will also play a part in the actual maximum pressure you can run; a tyre that is a fair bit wider than the rim wil exert a lot more lateral strain on the rim at high pressure than a narrower tyre, increasing the risk of splitting the rim down the guts. At the other end though, you can't go too narrow with the tyres, otherwise they don't hook into the rim beads properly and can br prone to blowing off. Plus the sidewalls stand up too straight and you lose a lot of the suspension effect of the tyre. If your rims are 30mm internal width for example, you don't really want to go any narrower than about 40mm tyre.Generally accepted wisdom is that regardless of tyre size, optimum pressure is that which results in "squish" when loaded of 15% of the tyre's profile height (basically the same principle as suspension sag). Therfore optimum pressure is not only dictated by tyre size, but by rider (+ stuff) weight as well.
 
Top