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Discussion Starter · #1 ·
I ordered a set of Carbon rims in the 34mm inner configuration. I admit I did it a bit spontaneously upon the recommendations of some friends. I have researched quite a bit since then and discovered almost all of the wheel manufacturers, and bike manufacturers are at 30mm inner.

Is this 3.5mm difference going to badly hinder the performance of 2.5 WT or 2.6 WT? The smallest tire I would consider ever running would be 2.4.

After some research it seems that the tire makers try to keep their rim width recommendations within ETRTO guidelines. Is it possible those guidelines lag a little? Is the reason that every single bike maker specs 30mm + or - 1mm in the enduro bikes because that is better or because that is what ETRTO recommends and the rim makers are making?

So, is that 3.5mm, (slightly over 1/8") going to flatten out my tread pattern too much and reduce the flex and absorption of the sidewall too much?

Any rear world experience with the wider rims? Thanks!
 

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I think you're going to get a lot of strong opinions, all saying different things.

I'm interested as well though because I want to get new 29 wheels for running both 2.4 and 2.6. I'm leaning toward 30 inner but I wonder if something like 32-33 would be better for the 2.6 up front when it's low pressure.
 

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You'll be just fine on 2.5/2.6 WT tires. It may square off a 2.4 a bit, but you may not even notice.

More information about your bike, local terrain, and weight would yield more relevant responses.
 

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Rollin 29s
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I am going to hate myself for ordering 34mm inner, 29" rims?

My Ripmo (GX build) came with the Ibis 938 34mm / 38mm wheelset, and the biggest change from what I'm used to (ZTR Flow - 22.6mm ID) aside from being able to run wider 2.5" tires is the low pressures I can run and superior traction due to pressures and tire width.

I weigh 210-ish and I never exceed 20psi. That would have destroyed my tires and Stan's rims.

I love the wider rims.

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My Ripmo (GX build) came with the Ibis 938 34mm / 38mm wheelset, and the biggest change from what I'm used to (ZTR Flow - 22.6mm ID) aside from being able to run wider 2.5" tires is the low pressures I can run and superior traction due to pressures and tire width.

I weigh 210-ish and I never exceed 20psi. That would have destroyed my tires and Stan's rims.

I love the wider rims.

Sent from my iPhone using Tapatalk
Telling someone you don't know (riding style and terrain) they can run under 20psi because of rim width is pretty foolish. I run 2.5's also and if I ran less than 20psi those carbon hoops would last about 100 yards.

Tire pressure is largely dependent on terrain and riding style. Personally for 2.5's I think 30mm ID is the sweet spot.
 

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I ordered a set of Carbon rims in the 34mm inner configuration. I admit I did it a bit spontaneously upon the recommendations of some friends. I have researched quite a bit since then and discovered almost all of the wheel manufacturers, and bike manufacturers are at 30mm inner.

Is this 3.5mm difference going to badly hinder the performance of 2.5 WT or 2.6 WT? The smallest tire I would consider ever running would be 2.4.

After some research it seems that the tire makers try to keep their rim width recommendations within ETRTO guidelines. Is it possible those guidelines lag a little? Is the reason that every single bike maker specs 30mm + or - 1mm in the enduro bikes because that is better or because that is what ETRTO recommends and the rim makers are making?

So, is that 3.5mm, (slightly over 1/8") going to flatten out my tread pattern too much and reduce the flex and absorption of the sidewall too much?

Any rear world experience with the wider rims? Thanks!
Maxxis originally stated the WT's were designed for a 35mm inside width rim then expanded that to say 30-35 as they received questions from people with narrow rims. You will be fine and it will give you better support if you chose to go to 2.6 tires.
 

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Rollin 29s
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Telling someone you don't know (riding style and terrain) they can run under 20psi because of rim width is pretty foolish. I run 2.5's also and if I ran less than 20psi those carbon hoops would last about 100 yards.

Tire pressure is largely dependent on terrain and riding style. Personally for 2.5's I think 30mm ID is the sweet spot.
I didn't tell him what to run, I simply reported my experiences with 34mm rims. Also, Ibis 938 rims are aluminum, not carbon.

My local trails are very rocky, so I'm not going easy on these wheels at low pressures. Also not doing 4' drops.

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I didn't tell him what to run, I simply reported my experiences with 34mm rims. Also, Ibis 938 rims are aluminum, not carbon.

My local trails are very rocky, so I'm not going easy on these wheels at low pressures. Also not doing 4' drops.

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You're right but it's the impression that your post gives. He ordered carbon rims... alloy dings, carbon shatters.
 

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My 2016 Stumpjumper comes stock with 31mm rims spec'd for 2.35 tires. I'd agree that the 34 will be suited for a wider tire, but I haven't had experience with varied combinations.

Just pointing out that the manufacturer of my bike paried 2.35 tires with 31mm rims. From how it sounds, it should work well, but maybe a little more squared off -just as mentioned above.

Are there different tires that have different profiles -a taller sidewall tire will keep a rounded profile better than a shorter sidewall tire, for example.
 

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Discussion Starter · #12 ·
Thanks for all the replies. I ride Colorado Front Range Trails. 2' to 3' is my absolute max drop. There is a lot of rock where I ride. Deer Creek, Chimney Gulch, Oil Well Flats, etc, White Ranch. I am definitely not even close to the category of an Enduro racer, but I also don't just ride XC or flow trails.

I think this will be a question that will come up more and more as the Chinese carbon rim makes are offering all these wider widths, while the mainstream seems to be at 30mm.

It is good to know the Ripmo has a 34mm I rim spec. That is the first big bike I have found that has anything much wider than 30.
 

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Bontrager tires are designed for wider rims than some others. high volume more rounded tread. You can run a 2.4 XR3 Team on that rim. Or an XR4. 20% sale through Monday. Order off the site for free ship to a local dealer.
 

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Discussion Starter · #17 ·
I was actually able to change my order to 30.5 mm inner rims due to the great customer service at EIE Carbon. It is a 38.5 mm outer and 30.5 inner so it should be a pretty robust rim lip of 4 mm. I spent a long time researching and I think I could have lived with the 34mm inner, but I feel at this point in tire offerings that the 30.5 is still more versatile.

The fact that Ibis is offering 34mm and 35mm inner dimensions is encouraging and I think maybe it will become more mainstream.

I don't see anything beyond 2.6 ever being popular for trail and enduro riding on 29 but maybe even 2.6 and under tires will have their casing profiles optimized for wider rims? I realize Maxxis WT optimize knob spacing and size, but I wonder if the actual casing profile can be changed.

Thanks for all the comments.
 
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