Rims.. How wide is it worth going?

[The Reverend]

I run the Derby rims. Pretty solid, not a single issue and I'm 105kg.
Main thing I like about the wide rims is the ability to run lower tyre pressures as the Sidewalls are very well supported.

I think Ibis use the Derby rims.

Tyre profile gets very square. Matter of preference if you like that.

I'd love some as they look beautiful and they review well. I bet you're happy with them.

 

[Zaf]

I've had nothing but good results with going wide.
The Light Bicycle 38mm on my Stumpy have been running Minion 2.3 DHF and SS's on them, they're super stiff wheels and the tyre volume and profiles have been fantastic. It's just going to be a judgement call on the tyres you need for the bike you're putting the wheels on. I can't see that bike using anything that's not a 2.3-2.5 Minions, Ardent's and Ikon's (on the rear at least), none of which have issues with the squaring of their profile.
The only tyres I've seen go really square on their profile with wide rims were 2.4 Ardents on 50mm Rabbit holes, and High Roller II's (But that said, I just took High Roller II's off my Yeti's 35mm and they were fine).

Otherwise, traction has been amazing and stable, the hardest part is finding the balance of enough pressure to stop the tyres pinching the rims and dinging, which again, is largely variable with the trails you're riding more commonly. It's the main concern with rocks and low pressures out here, but I haven't been able to burp them yet.

 

[ianganderton]

What wide aluminium rims are you using?
http://www.rotorburn.com/forums/showthread.php?t=299336

 

[The Reverend]

I've had nothing but good results with going wide.
The Light Bicycle 38mm on my Stumpy have been running Minion 2.3 DHF and SS's on them, they're super stiff wheels and the tyre volume and profiles have been fantastic. It's just going to be a judgement call on the tyres you need for the bike you're putting the wheels on. I can't see that bike using anything that's not a 2.3-2.5 Minions, Ardent's and Ikon's (on the rear at least), none of which have issues with the squaring of their profile.
The only tyres I've seen go really square on their profile with wide rims were 2.4 Ardents on 50mm Rabbit holes, and High Roller II's (But that said, I just took High Roller II's off my Yeti's 35mm and they were fine).

Otherwise, traction has been amazing and stable, the hardest part is finding the balance of enough pressure to stop the tyres pinching the rims and dinging, which again, is largely variable with the trails you're riding more commonly. It's the main concern with rocks and low pressures out here, but I haven't been able to burp them yet.

Thanks Zaf, good to hear 38mm is working for you. I like the idea of the larger profile but I've got to consider the clearance at the rear. As I'm considering converting a 26" which has a lot of clearance, that disappears once I go to 27.5.
The manufacturer state a 2.25 will work but once I jump up in width it makes that margin smaller.

 

[The Reverend]

What wide aluminium rims are you using?
http://www.rotorburn.com/forums/showthread.php?t=299336

Thanks for that mate. Didn't even register its existence so I appreciate it.
I'll give it a good look through! :^)

 

[ianganderton]

Thanks for that mate. Didn't even register its existence so I appreciate it.
I'll give it a good look through! :^)

No worries

This article I found and posted is particularly relevant

http://www.mtbiking.com.au/how-to/bike-tech/why-choose-wide-rims

 

[teK--]

For tight XC tracks I could see a nice flat profile being beneficial as having something like an Ardent is pretty shit in the transition from centre to side lug so having a flatter tyre would see your cornering traction increase on tracks that don't allow much leaning in corners.

I could be totally wrong though.

This is my experience. I tried tyres that others swore gripped like crazy on wide rims, but when I leant the bike over there was hardly any grip.

 

[No Skid Marks]

Didn't read thread sorry.
IMO 35mm external, choose tyres wisely. Maxxis are releasing "WT" tyres with thread forther around side walls to counter act flattening profile. More brands will no doubt follow suit as wider rim provides a stiffer tyre with stiffer side walls. Maybe wider than 35mm depending what tyres evolve.
30mm wide if you wish to use most current tyres.

 

[SummitFever]

Developing tyres for the wider rims is not as easy as just making them bigger or more rounded. In doing so, you run the risk of getting back all of the traits of normal tyres on skinny rims. eg the sidewalls will not be straighter (and hence provide more support at lower pressures) if you design the tyre to balloon out more on a wider rim (which is what you need to do to get a more rounded profile).

 

[teK--]

Didn't read thread sorry.
IMO 35mm external, choose tyres wisely. Maxxis are releasing "WT" tyres with thread forther around side walls to counter act flattening profile. More brands will no doubt follow suit as wider rim provides a stiffer tyre with stiffer side walls. Maybe wider than 35mm depending what tyres evolve.
30mm wide if you wish to use most current tyres.

The WT tyre does not have the side knobs further up the sidewall. There was a thread somewhere on pinkbike or mtbr (I forget) where a maxxis tyre designer was posting on there and they confirmed the change in the WT versus normal casing (aside from the bigger volume in casing), is the distance between the centre, transition, and corner knobs.

 

[The Reverend]

No worries

This article I found and posted is particularly relevant

http://www.mtbiking.com.au/how-to/bike-tech/why-choose-wide-rims

That's a good perspective. Admittedly a sample of one but they also have SRAM's view which is that 30id seems the sweet spot.
Last thing I need it extra weight at the rim / tyre of all places.

 

[The Reverend]

This is my experience. I tried tyres that others swore gripped like crazy on wide rims, but when I leant the bike over there was hardly any grip.

This is important for me as I love leaning this bike over, more than my other rigs so I'd rather not lose that feeling / sensation.

 

[ianganderton]

That's a good perspective. Admittedly a sample of one but they also have SRAM's view which is that 30id seems the sweet spot.
Last thing I need it extra weight at the rim / tyre of all places.

On weight I did read somewhere the argument that alloy was lighter than rubber so wide rims are a weight effective way of adding volume to a tyre

As well as the other benefits of increased support for the tyre wall

 

[The Reverend]

The WT tyre does not have the side knobs further up the sidewall. There was a thread somewhere on pinkbike or mtbr (I forget) where a maxxis tyre designer was posting on there and they confirmed the change in the WT versus normal casing (aside from the bigger volume in casing), is the distance between the centre, transition, and corner knobs.

It looks like going over 30id has some serious implications for tyre choice indeed.
I'll keep reading and I'm glad I didn't make a snap decision. :^)

 

[Zaf]

Does anyone have a list of tyres they've had issues with on wider rims? What rim ID, what volume tyre and what the issue was?

As I've written previously I've not experienced any squaring problems with the 38mm yet, that might very well be due to the tyre choice that matches the wheel to begin with. I did originally think the minion SS squared off a bit, until I saw the same tyre mounted to an ENVE M60. It was squarer, but not dramatically so, and not in a way that has affected performance negatively.

 

[Warp]

Developing tyres for the wider rims is not as easy as just making them bigger or more rounded. In doing so, you run the risk of getting back all of the traits of normal tyres on skinny rims. eg the sidewalls will not be straighter (and hence provide more support at lower pressures) if you design the tyre to balloon out more on a wider rim (which is what you need to do to get a more rounded profile).

This. Wouldn't you need shorter sidewalls?? But then how short is short before you start losing cushioning. Maybe I'm not thinking this through?

I need to replace my rims sometime this year. I think for average trail riding/XC I'll stick to 25-30mm internal and will see if I can push it to carbon.

 

[No Skid Marks]

Developing tyres for the wider rims is not as easy as just making them bigger or more rounded. In doing so, you run the risk of getting back all of the traits of normal tyres on skinny rims. eg the sidewalls will not be straighter (and hence provide more support at lower pressures) if you design the tyre to balloon out more on a wider rim (which is what you need to do to get a more rounded profile).

I never said larger bag/casing. Just tread going further around the existing casing. So when it's stretched out on a wider rim, the side knobs don't end up on top and therefore flattened out.

 

[No Skid Marks]

The WT tyre does not have the side knobs further up the sidewall. There was a thread somewhere on pinkbike or mtbr (I forget) where a maxxis tyre designer was posting on there and they confirmed the change in the WT versus normal casing (aside from the bigger volume in casing), is the distance between the centre, transition, and corner knobs.

That's what I said. Wider tread so further around casing. So it puts the side knobs back on the sides. Where a normal tyre on wide rim puts the side knobs more to the center, so on top and square profile shape.

 

[No Skid Marks]

This. Wouldn't you need shorter sidewalls?? But then how short is short before you start losing cushioning. Maybe I'm not thinking this through?

I need to replace my rims sometime this year. I think for average trail riding/XC I'll stick to 25-30mm internal and will see if I can push it to carbon.

With the same size casing on a wider rim, you are effectively shortening the side walls. By Maxxis making the tread wider, it is in effect further down the side wall, but because it's on a wide rim, the wide rim is making the casing a wider diameter, so the top of the tyre is wider.
Put your nose picking finger and thumb together making an "Okay" hand signal. Now make a 20mm gap between them. Picture your fingers as a cross section of the tyre. Now open the gap to 30+mm. You can see what happens to the tyres profile.

 

[ianganderton]

I wonder what the optimum volume is for tyres by use and by wheel size

I've moved from a 19mm id to a 30mm id rim but I'm still using the same 2.4 inch tyre. The circumference of the tyre has increased by 11mm