I’m planning a new gravel bike build. I’m considering two options that would be under 1200G to support gravel tires 45mm or wider.
XC930
30mm internal, 37mm external
AR25
24mm internal, 29mm external
Assuming the bike frame supports 47MM tires or above (have not decided on exact frame):
- Is the wider rim option better? Similar to my experience on road, I am thinking about relatively wide rims reduce the balloon effect on tires, more stability on handling.
- will the bike frame have any potential issues (I assume not if the tire is wider than the rim)?
- the wider rim may be hookless only - I haven’t looked up if most gravel tires of this size are hookless.
- what min tire size could I do on the wider rims? Would 42MM be problematic for example?
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Is the wider rim option better?
I would go with the wider rim.
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will the bike frame have any potential issues (I assume not if the tire is wider than the rim)?
No issue due to the rim itself but… A wider rim will make the same tire balloon wider generally (but not always) so this could be an issue if you want to run say a 47mm spec tire in a frame that is limited to 47mm but the wider rim makes it larger. But this isn’t really a problem since can just use a narrower spec tire.
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the wider rim may be hookless only - I haven’t looked up if most gravel tires of this size are hookless.
Hookless is pretty common on 25-30mm internal width rims for mtb and gravel. From what I’ve read hookless should be fine at the low pressure for gravel. I know for sure its fine at mtb pressure using 25-30mm rims. Seems to be only the higher pressure road stuff can be the problem.
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what min tire size could I do on the wider rims? Would 42MM be problematic for example?
My friend has no issue running 33mm cx tires on 25mm internal width rim. So I would think you would be fine with a tire down to 40mm on the 30mm internal width rim.
All this being said, a very wide tire will still also work fine on the 24mm rim. I think its only more important if you are picky about the end result tire shape. When in doubt, wider seems to be the way to go.
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If you go with the 30mm internal rim, you’re outside of ETRTO specs for a 45mm tire, but 47+ I think should be OK based in Schwalbe’s chart.
That’s not to say it won’t work, but I suspect most manufacturers would be hesitant to recommend it. I wanted to try Tufo Thundero 700x44 on my Roval Control Carbon wheels (hookless 29mm internal), and the manufacturer wouldn’t recommend it. Specialized, on the other hand, said I’d have no problem with 700x47 Pathfinders.
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Interesting. I’m thinking of using the S-Works Pathfinder which comes in 42MM but I’ve read balloons out quite a bit on wider rims. I think it hits 45/46mm on 25 internal rim widths so I suspect I’ll be 47+ on a 30mm internal rim. (I ordered the XC930, 37 external, 30 internal)
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@teddygram has wide gravel wheels from what I recall. He might have some good advice on what works.
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I have been running a 30id/40od rim for 3-years now.
I bought them for racing way back when with a theory of running 35mm tires that are fully optimized and keeps weight down.
My theory was correct, I was able to run 35mm tires and they ballooned to 40mm (39.6mm) actual measured. This gave me light wide tires that optimized IMO a race setup. They also marched the rim profile very well.
When I tested 38’s on the rims they would typically blow out to 42mm actual measured.
My rims are available in hook or hookless, none the less I had (1) issue with some Rene Herse tires that blew off them. Outside of that I have zero issues even at high pressure on any other tire I tested. I have a thread here somewhere about the blowoff but on phone and cant look now.
I would never put anything smaller than a 35mm on that size rim though.
What specific questions do you have?
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This is what I was thinking as well - wanting a race quality setup (greater tire width on wider rims, less weight) with race-less skills 
Originally, I asked these about 30m internal, 37mm external wheels, but I think they’re answered pretty well now:
- Is the wider rim option better? Similar to my experience on road, I am thinking about relatively wide rims reduce the balloon effect on tires, more stability on handling.
- will the bike frame have any potential issues (I assume not if the tire is wider than the rim)?
- the wider rim may be hookless only - I haven’t looked up if most gravel tires of this size are hookless.
- what min tire size could I do on the wider rims? Would 42MM be problematic for example?
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- Is the wider rim option better? Similar to my experience on road, I am thinking about relatively wide rims reduce the balloon effect on tires, more stability on handling.
My experience is yes, unless you run a very large tire the wider rim for gravel just like mtb helps a lot with the tire shape. My 35mm combo squares the tread off more bringing the side lugs more inward which in my particular case gives a better corner dig.
- will the bike frame have any potential issues (I assume not if the tire is wider than the rim)?
Frames are non-issue here. The only thing that matters with the frame is if it can handle the tire/rim width
- the wider rim may be hookless only - I haven’t looked up if most gravel tires of this size are hookless.
There are tons of hookless options for gravel tires and growing all the time.
- what min tire size could I do on the wider rims? Would 42MM be problematic for example?
No issues with 42mm, I have not tested smaller than 35mm however and may try some 33mm in the upcoming weeks. I think the 33mm in all honesty may be dangerous.
For reference here are the NXT45AGX-Z, I fully recommend these rims. They are also tubless ready without holes drilled in the rim bead (no rim tape required)
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I’m a fan of wide rims as well… I’ve got a set of the 36mm deep version of the above illustrated wheels from Nextie(30mm internal, 40mm external, hookless). I’ve mounted several sets of tires on them, currently running some 2.1" Thunder Burts on my Mosaic. I have a set of Pathfinder 47’s that I dry mounted, but honestly they squared off a bit too much for my liking and for their tread pattern. So this is to say that not every tire in a certain size will work as you might want it to. And as mentioned, you have to pay attention to actual WAM of the tire when inflated… Some 2.25" Mezcals blew up to 2.4" on them.
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My 47mm a pathfinder pros measure 45mm wide on 24mm internal hookless rims.
I’d be concerned about 42mm on 30mm rims becoming too flat where you’re losing the benefit of the smooth center strip on hard surfaces and having all the knobs contacting the road and creating more rolling resistance
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Any suggestions on tires/tire sizes that you liked on the wider rims?
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That make sense, wondering about that too. Did you say the 47mm measure smaller (as 45) on 24mm?
Yes, my 47mm tires measure 45mm on a 24mm rim
45 on 24 seems right. Mine measure 47 on 25 hookless (WR45) but that was only after riding them for a while.
I’ll echo the concern about squaring off a small pathfinder too much, but that’s only going to be relevant for tires of that tread type with a really significant difference between centre and side knobs - you can always go to those smaller sizes with a more uniform tread type.
Only other potential setback of an extra wide rim that I’ve not seen mentioned yet is that you end up exposing your sidewalls (and sometimes the rims themselves) to more impacts. Depending on the tire this can mean you suddenly have issues with sidewall cuts on a model that’s never shown the slightest bit of sidewall damage before.
I’d still choose to err on the side of a rim that’s too wide rather than too narrow - trends are going to keep going wider for the foreseeable future which means tires are just going to get optimised for wider and wider rims. You’re going to end up with more tire options as time goes on rather than less.
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This is a tough one and a debated topic, I personally have not found the need of more than a 40mm measured tire.
That said, my absolute favorite tire to date is a 700x35 Pirelli Cinturato H. The tire checks off every box for me and feels snappy and peppy in the smaller frame from saving the weight. It has some fairly tall side lugs too so it does okay on single track. They are faster IMO than my pathfinders on the road and have better dry uphill traction than the pathfinders under load.
My least favorite tire to date is a 700x38 panaracer GK slick. The tire feels lazy and when cornering it try’s to auto steer. The traction is not great on them in almost all conditions excluding tarmac
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It’s been shown over and over again that width doesn’t really matter.
I wouldn’t go to the 30mm extreme for two reasons. 1) the tire is probably designed for a 21-25mm. The bigger rim will shape the tire wrong. 2) The rim won’t be usable as a road rim or smaller tire rim if needed. 3) weight (but those are light rims)
I would suggest 650b rims here for better standover height.
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If a difference of 5mm or even 10mm on your tire is of concern to your bike fit in anyway, including standover height, you are 100% on the wrong size bike…
Make all the difference when it’s wrong! Not all bikes have low top tube - CX bikes for example. Also, you’ve got a few extra mm for knobs and stuff.
At a stoplight having your bike 5-10mm too high can make it a pain in the bits! Off road, on uneven ground, may make standover even worse. It’s just nice to be able to comfortably stand over the top tube.
When I put more knobby 50x700c on my Checkpoint, I got toe rub, couldn’t stand over it easily, and it was like mounting a full suspension MTB at every light. That was a 13-15mm difference though.
Also, the only time I’ve sized a bike by standover is my short spouse. I’m right in the middle of the integrated seat post with tall mast and running a 120mm stem on my 58cm Checkpoint… I’m sure I don’t need to go smaller hahahahaa
- the tire is probably designed for a 21-25mm. The bigger rim will shape the tire wrong.
I think I disagree with this statement, shaping the tire could be better or worse
- The rim won’t be usable as a road rim or smaller tire rim if needed.
This is absolutely true, but OP is making it a dedicated gravel wheelset so that is not a very good point.
- weight (but those are light rims)
The rim weights are pretty dang close now, a road specific rim in a 24/30 in 44mm depth is 420g while a gravel specific rim that is 30/40 in 45mm depth is 450g. That’s 30g difference which really is not that much in a gravel discussion, tire choice will determine weight long before that is
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I did another tire test tonight on my rims
Specialized Tracer Pro - 700x38
They measure to an actual width of 44mm measured
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