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Discussion Starter · #1 ·
I am looking for a rim that I can use to set up a 37mm Tubeless Ready tire (UST compliant bead). I anticipate running the tire at around 65psi max in the rear. I am also looking for an inner width of 19-23mm (preferable on the wider end).

I am getting a bit confused as to what (if any) tubeless ready rims can accommodate this. I was all set to go with the Stan,s Grail rims, but I see that it maxes at 116psi for a 23mm tire, and only 45psi for a 32mm tire, which leads me to believe it would be even lower for a 37mm tire.

For most other rims I can't find any info on max pressure. I thought around 40-45 psi was max for most mtb rims, but maybe that is just for Stans? (I have Flows on my mtb).

The tire is a Compass Bon Jon Pass 35c (measures 37mm). It is tubeless ready (UST compatible bead). I use it for a mix of pavement and dirt/gravel roads. However, I could see myself using other more aggressive tires for rougher conditions in the future.

Thanks for any info.
 

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Lots of rims will work, however I have to wonder why you would use such high pressure on a 37mm tire? The inflation info given on the Compass site suggests that you wouldn't want to use such high inflation pressure unless you and your bike and gear are in the ~270 lbs range.

If that's the case, then something really robust like a DTSwiss 511 (32mm tall x 18mm inside, 530g) will be a good rim choice.

An Easton ARC24 would be a good choice in addition to the R90SL, with the benefit of being available in 32h drilling (the only drilling it comes in, in fact), which will be beneficial if 65 psi is appropriate inflation for your system weight.
 

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Discussion Starter · #4 · (Edited)
Lots of rims will work, however I have to wonder why you would use such high pressure on a 37mm tire? The inflation info given on the Compass site suggests that you wouldn't want to use such high inflation pressure unless you and your bike and gear are in the ~270 lbs range.

If that's the case, then something really robust like a DTSwiss 511 (32mm tall x 18mm inside, 530g) will be a good rim choice.

An Easton ARC24 would be a good choice in addition to the R90SL, with the benefit of being available in 32h drilling (the only drilling it comes in, in fact), which will be beneficial if 65 psi is appropriate inflation for your system weight.
Thanks for the rim suggestions. Yeah, I am definitely looking for 32 hole rims.

That is the very chart I have used for years. And it has worked out just about right for me, with a few tweaks.

My combined rider+bike weight (with no extra load on the rear) is ~213 lbs.

That tire inflation chart yields ~43/63 (front / rear) for a rider + bike with a weight distribution of 88/125 lbs front/rear for a 35mm tire (which this tire started out as for me. It has since stretched to 37mm, but the feel is still about right.

I typically run 50/60 front/rear.

The reason I go higher in the front is due to the front tire squirming in hard turns on pavement under 50 psi. I am hoping that a wider rim helps with this, thus my interest in rims on the wider side of 19-23mm.

As far as the rear, i can usually get away with pressure in the upper 50s if I am not carrying extra weight on the rear, but even a small load on the rear rack can give me pinch flats on potholes or uneven pavement.

So, even though that chart gives me 55 psi for a 37mm tire with my normal weight distribution, I need to allow for extra loads on the rear. This is how I came to the 65psi max requirement. I could likely get away with a little less if need be.

I have played with lower pressures, and this is what works for me.

I realize that tubeless will allow lower pressure in the rear due to elimination of pinch flats, but my experience from MTB has shown me that the psi at which you encounter rim strikes is not all that much lower than the psi at which you get pinch flats with sturdy tubes.
 

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Discussion Starter · #5 ·
So, I talked to a few manufacturers on the phone and got some answers.

WTB (Frequency XC, Frequency Team, and KOM) do not have a set max psi with tubeless. You can go with the tires max psi (if it is a ust compliant bead).

Pacenti SL25 and CL25 have a max pressure of 77 psi for a 37mm tire (it varies with different tire sizes), again, assuming UST compliant bead if tubless.

I did not call Easton, but found a tech sheet with the max pressure for the R90 SL: 72 psi for a 37mm tire.

Regarding the Compass Bon Jon Pass tire: If it is one of the newer ones with the "90 psi max" written into the blue decal, then that is the max psi with or without tubes (assuming a ust compliant bead hook on the rim).

I'm now deciding between the going to go with the Pacenti SL25 (20mm internal width, 450g), and the Frequency Team i23 (23mm internal width, 504g). Leaning towards the Pacenti.

The WTB KOM 21 has the perfect internal width (21mm), and the weight was attractive (420g) but I was a little leery of it's light weight at that width, and after reading some reviews had some concerns about the strength.
 

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I have SL25s for gravel tires and 40mm WTB Nanos tubeless or Clement MSO wtih tubes have both worked well on them. I don't ride at 65psi though, most I've put in them was 50psi for riding, I normally have 45 in them and that handles 185lbs of me plus plenty of weight on the bike for 100+ endurance rides.
 

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I'm getting different answers from the chart for your total weight and distribution from what you get (nominal mid point of 48psi at 220lbs rider + bike, and that's a generously high read of the chart) but if that's what you like I won't try to change it. I weigh a lot less (160 when I'm not double fisting twinkies) so my dynamics are much different from yours. Out of curiosity, what do you use on your mountain bike? I use around 19 front/22 rear, and I know I can go lower.

Anyway, SL25s are great rims - they've basically been perfect for us - and they're about to get rare.
 

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Discussion Starter · #9 ·
I'm getting different answers from the chart for your total weight and distribution from what you get (nominal mid point of 48psi at 220lbs rider + bike, and that's a generously high read of the chart) but if that's what you like I won't try to change it. I weigh a lot less (160 when I'm not double fisting twinkies) so my dynamics are much different from yours. Out of curiosity, what do you use on your mountain bike? I use around 19 front/22 rear, and I know I can go lower.

Anyway, SL25s are great rims - they've basically been perfect for us - and they're about to get rare.
Look halfway between the 32mm and 37mm lines, just to the right of 121 lbs. It is over 60 psi.

I was mistaken earlier, mine actually measure 34mm, not 37mm. 37 is what most people report, though, and it is what I predict mine will be closer to on a new wider rim.

Regardless, that is a starting point, I go with what works.

MTB? Depends on the tire size, casing, tubeless vs tubes, and which bike.

On my Turner 5-Spot with tubeless 2.3s (with thin sidewalls), I run about 23 f / 27 rear. Limits are pretty much the same as on the road bike: Lower in the front and it gets too squirmy, lower in the rear and I start dinging the rim and losing support in turns.
 

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I'm getting ready to build up so Pacenti TL28 I have had around for a while. My interntions are to use them for Gravel so I'll be running some 40's Happy Mediums on them tubeless. I'm guessing pressure will be around 33 for my 165lb self. I was also planning on trying them with my 28c Conti 4000 with tubes. I'm guessing I'll be at about 55 lbs.

I recntly built a Cat 1 buddy of mine some Crest MK for his cross bike. He is a little guy around 145. He reports running 20 lb in 33c Clement MXP set up tubeless. Said the ride and traction was incredible.

We are starting to really explore how wide we can go on Cx and gravel type wheels and tires. I know there are charts with recommendations but I think we are far beyond the recommendations. I believe if a wide rim has a resonable weight to it, then it should be able with stand a little extra pressure from a tubed road tire. Tubeless road, I'm not so sure I want to push the envelope there.

Next i'm going to tear the label off my mattress and see what happens.
 

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Discussion Starter · #12 ·
We are starting to really explore how wide we can go on Cx and gravel type wheels and tires. I know there are charts with recommendations but I think we are far beyond the recommendations. I believe if a wide rim has a resonable weight to it, then it should be able with stand a little extra pressure from a tubed road tire. Tubeless road, I'm not so sure I want to push the envelope there.
If I was riding primarily gravel and dirt roads, I'd be looking at 1.8"-2.1"-ish tires, and a bike that could run them ("Monster Cross"?). I had my Karate Monkey set up with 2.2" Racing Ralphs for a while and spent a lot of time exploring forest service roads on SW Virginia. I could have gone a little smaller, but they were fantastic for that.
 

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The caption on the chart say for 100kg rider and bike that it would be 45/55 for a 37mm tire, and the original Berto thing actually says somewhere between 45 and 48 for 220lb, but again not going to convince if what you're using works for you. But I'm like Enoch562's friend with the tubeless MXPs. I race with my cx tires at like 23f/26r, any more than that and it's impossible to drive the bike correctly, you're just getting the heck bounced out of you.

And, speaking of Enoch562, I didn't want to have to pull rank but I'm from the Mattress Police.
 

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Discussion Starter · #14 · (Edited)
The caption on the chart say for 100kg rider and bike that it would be 45/55 for a 37mm tire, and the original Berto thing actually says somewhere between 45 and 48 for 220lb, but again not going to convince if what you're using works for you. But I'm like Enoch562's friend with the tubeless MXPs. I race with my cx tires at like 23f/26r, any more than that and it's impossible to drive the bike correctly, you're just getting the heck bounced out of you.

And, speaking of Enoch562, I didn't want to have to pull rank but I'm from the Mattress Police.
My rear wheel has 125 lbs weight on it, and the tire size is 34-35mm (see my correction above). If you are not getting just over 60 psi from that chart, then I don't know what to say, one of us needs help reading a chart. It seems very clear to me that at 60psi, I am riding pretty much exactly what the chart indicates.

And again, to reiterate, The 65 psi figure comes from adding in some headroom to carry loads on my rear rack.

Also, that example from the chart description assumes a 45/55% weight distribution. From the numbers I gave, that is not mine. Mine is more like 41/59%, which in that case would give you 59 psi for the rear.

WhiIe it may be interesting I don't really find it relevant what people are running for cx, I'm not racing CX. I get pinch flats at double that pressure on the roads here. Different animals.
 

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This calculator is based on FB's chart and makes it easier to consider f/r weight distribution and inflation pressure change:
Bicycle tire pressure calculator

Berto's chart is nothing more than an approximation of the pressure needed for a particular weight and air volume to result to a loaded tire drop of 15%. The 15% value is an arbitrary number Berto used based on the tires available in 1990 - typically much narrower and stiffer than today's tires. Then he took a statistical average and came up with the 15%. Case and point here is that your results will vary if you take a supple tire like the OP is using and inflate it to Berto's pressures - you will find you need more pressure to come up to 15% drop.
IMO, these charts need to be used just as a starting point and then adjust pressure up or down depending on what you are after.
 
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Discussion Starter · #16 ·
This calculator is based on FB's chart and makes it easier to consider f/r weight distribution and inflation pressure change:
Bicycle tire pressure calculator

Berto's chart is nothing more than an approximation of the pressure needed for a particular weight and air volume to result to a loaded tire drop of 15%. The 15% value is an arbitrary number Berto used based on the tires available in 1990 - typically much narrower and stiffer than today's tires. Then he took a statistical average and came up with the 15%. Case and point here is that your results will vary if you take a supple tire like the OP is using and inflate it to Berto's pressures - you will find you need more pressure to come up to 15% drop.
IMO, these charts need to be used just as a starting point and then adjust pressure up or down depending on what you are after.
Doh!! I forgot all about that calculator.

Looking at the numbers I originally used as a starting point (I have them written down), that must be where I got them from, because they are identical.

Since my tires were roughly half way between 32mm and 37mm, I took the average of the two results for each tire (one with 88 lbs and the other 125lbs load) and used that as a starting point. I detailed above how I then ended up with the pressures I now use most often.
 

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I'm really just trying to help. Your subject line says 37mm tires, as do most measurements of the tire on wider rims. Wider rims such as you are looking for will increase tire width, better support the tire thus reducing squirm, and help avoid pinch flats at any given inflation.

Your stated weight distribution is very rear-biased, which is incongruous with your report of feeling front tire squirm with a much more front-wheel heavy inflation distribution on your mountain bike (46/54%). Normally mountain bikes are more rear-heavy than other bikes, and Berto's distribution is from typical "sport touring" setups, so it's a bit incongruous to me that you would be so much rear heavy than that on the bike on which you'll use these tires. But if you say you are, you must be.

I have once pinch flatted a tubeless road tire. I was quite certain that I'd broken the rim, or my fork or bars or stem given the violence of the impact. Fortunately not, but my wrists were in considerable pain for several days. Point being that tubeless tires do not pinch flat easily at all.

My recommendation of the ARC24 was in fact informed by my familiarity with and consultation with their pressure chart. I try never to make a recommendation without a lot of "why" backing me up, as so often happens on forums. My reputation is here, I don't do this stuff willy nilly.

Again, only trying to help. Enjoy your project.
 

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Discussion Starter · #18 · (Edited)
I'm really just trying to help. Your subject line says 37mm tires, as do most measurements of the tire on wider rims. Wider rims such as you are looking for will increase tire width, better support the tire thus reducing squirm, and help avoid pinch flats at any given inflation.

Your stated weight distribution is very rear-biased, which is incongruous with your report of feeling front tire squirm with a much more front-wheel heavy inflation distribution on your mountain bike (46/54%). Normally mountain bikes are more rear-heavy than other bikes, and Berto's distribution is from typical "sport touring" setups, so it's a bit incongruous to me that you would be so much rear heavy than that on the bike on which you'll use these tires. But if you say you are, you must be.

I have once pinch flatted a tubeless road tire. I was quite certain that I'd broken the rim, or my fork or bars or stem given the violence of the impact. Fortunately not, but my wrists were in considerable pain for several days. Point being that tubeless tires do not pinch flat easily at all.

My recommendation of the ARC24 was in fact informed by my familiarity with and consultation with their pressure chart. I try never to make a recommendation without a lot of "why" backing me up, as so often happens on forums. My reputation is here, I don't do this stuff willy nilly.

Again, only trying to help. Enjoy your project.
Yes, I know you are trying to help. Thanks.

I did not start this thread prepared to recall and discuss how I came up with my current pressures, so apologies if my story has meandered a bit and been confusing. It has been a year since I set up these tires, and it wasn't until I pulled out the sheet that I had written numbers down on and been reminded of that web calculator that I remembered just what I did.

I actually don't mind discussing these things at all. Tires, pressure, and related things are a bit of a geek out subject for me, though it is usually focused on mountain bikes.

Regarding weight distribution and the front tire squirming: One thing to keep in mind about any weight distribution estimates, is that they are static, when in fact weight distribution is dynamic.

I measured my weight distribution initially using my standard riding position on the hoods which is where I spend the majority of my time. I am almost always down in the drops on hard turns, and while I have not given it much thought up until now, I am certainly shifting weight forward, a carryover from mountain biking.

In any event, the 15% drop method is based on comfort and efficiency. In terms of pinch flats, needed pressures are going to vary greatly depending on conditions. The 15% method does not really deal with that.I definitely needed to start running higher pressures when I moved to Ithaca with a lot of very steep, pothole-riddled streets than I did living in the mountains of SW Virginia.

My experience has been that as far as tires and rims, road obstacles (such as potholes and uneven pavement) are the most brutal things I come across. Lots a speed, sharp edge hits, and less maneuverability on the bike (especially in terms of unweighting the rear wheel). At least for me, that is.

Another factor is dead, unsuspended weight. If I am carrying 5-10 lbs on my rear rack, that is far more brutal on a tire and rim than 5-10 lbs on my gut. These estimates based on rider+bike weight does not make that distinction, because it is not addressing pinch flats and/or rim damage.

Anyway, good discussion.
 
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