[Closed] Rim Width... snake oil or not?

I thought it was less about stiffness and more about the shape of the tyres sat on them?

Mark Weir doesn’t like wide rims, so I think horses for courses. I’ve got 21, 25 and a pair of 29mm internal wheels are in the post, so hopefully I’ll be able to offer better insight soon enough... 🤓

"I thought it was less about stiffness and more about the shape of the tyres sat on them?

Yep - the general opinion is that the wider rim provides better support for the carcass, so you'll have tyres that don't fold over as much in hard cornering. It also should mean you have a better contact patch (given the right tyres), as the tyre profile flattens slightly.

It should also mean you get less pinch flats/snakebites in the tyre about the bead, as the tyre doesn't compress as much in the same spot.

Given all of the above, you should then be able to run lower pressures, which in turn give you better compliance, comfort and grip.

The theory is great, and I thought it worked as stated in practice. But... My switch to the narrow DT rims feel otherwise somehow!

For me the difference is evident at lower tyre pressure. The lower the pressure the worse a narrower rim, and tyre attached to it, performs, feeling more squirmy, at the rear anyway. Comparing a 2.35 on an i21mm rim to a 2.4 on a i29mm

Yeah, I think Tomhoward has a good point there, volume and pressure are pretty linked.

I think wide rims and bigger tyres are possibly one of those things that us knobbers can benefit from, or maybe just <like>, which isn't the same, but which pros aren't fussed about because they want different things. I love a big soft sticky tyre, I don't mind if it rolls slowly if it's stopping me from crashing, and I like the feel. There are other knobbers that like a hard tyre and they probably don't gain from big rims the same way.

Yeah, I much prefer a wide-ish rim (30mm, but haven't tried wider..) because of the extra sidewall support. I went back to a 24mm rim briefly recently and was quite surprised how much it bothered me, with the amount of squirm I could feel when cornering. Dunno if the wider rims and my perceived "better" feeling equate to faster riding though. Can't say I noticed a difference in punctures or rimstrikes either. That might be because I tended to run higher pressure in the narrower rim to try to cut down on squirm.

Interestingly, a few EWS pro's prefer the narrower rims, though I'm not sure why. Last race I did I was queued up behind the Canyon team and Fabien Barel was giving Justin Leov a hard time because Leov had fitted an old narrower rear wheel to his race bike but hadn't changed the stickers to make it look like the new and "improved" wider version!

Me and a couple of mates were chatting about this the other day, jumping from a more traditional 22-25 id to 30-35 id.....are the tyres more stable? Can we run lower pressures? Have snake bites and the like gone? Answer to it all was no.

Is there a slight improvement in feel? Maybe.

Just taken my xc bike from 19id to 27id, this difference has been more profound.

On a side note, how the hell does anyone get away with less than 30psi on the rear with trail thickness tyres? This came up in the discussion too since we all thought the same. Must just straight line everything and never let the wheels leave the ground.

I've not had a pinch bite in 2 years since running wider rims.  Riding same stuff as normal on a Capra and Jeffsy, both at 17 - 20 psi.

So for me the wider rims work.

I've got a mix of wheelsets from I think 22.5 up to 30.

Generally running 2.3 tyres, either Maxxis, Schwalbe or Specialized.

I cant really notice a difference in them at all really. I can' get away with running the low pressures some people do either. 28/30 in the back and a min of 25 in the front, otherwise it just burps an EXO on the first half decent corner.

Maybe I could get away with less pressure on Double Down tyre, I know I can lose a couple of psi with Grid casings but the knock on effect issue is they noticeably dull the ride with the additional weight.

I’ve not got loads of wheelsets to compare, but I’m running 25mm internal width DtSwiss e1900s (650b) with a 2.5wt minion dhf Exo / 3c on the front and a 2.3minion dhr2 Exo / 3c on the rear. According to my track pump gauge I run around 25 psi at both ends with no burping / squirming and haven’t had a puncture of any description since I got the bike in May.

I may not be that hard on tyres though as my previous bike was on 19mm internal rims with inner tubes and 2.4” continental protection tyres and I only got a couple of pinch punctures plenty that setup at just over 30psi (both a BPW).

it's an interesting one. Joebristol according to Maxxis 2.5wt on a 25mm rim does not have any benefits.  If I understand it right they are actually saying its disadvantageous,. plus the extra cost and weight

http://reviews.mtbr.com/can-you-run-maxxis-wide-trail-tires-on-regular-rims

I noticed that when Cotic sent the new Flare Max to various magazines for testing it had Hope XC wheels (with a 19mm internal diameter) but moderately chunky WTB tyres. Judging by the video in their review the MBR guys were chucking it about a fair bit, but none of the reviews I've read had anything negative to say about the wheels. Maybe if somebody had told them that the rims were unfashionably narrow they'd have felt compelled to comment, but it doesn't sound as though it had a hugely negative effect.

I'd love to know how people can tell one rim is stiffer than another rim simply by riding it. Especially as they're attached to a big squishy bit of rubber.

Have snake bites and the like gone? Answer to it all was no.

the answer is tubeless, it works real well with a wider rim and of course you'll never get a snakebite puncture and can run much lower pressures because of it, this again makes good use of the wider rim

I’d love to know how people can tell one rim is stiffer than another rim simply by riding it. Especially as they’re attached to a big squishy bit of rubber.

Cos the tyre only squishes so much.  When I hit rock gardens or other large features at angles I can really feel the wheels deforming.  You might not have noticed where or how you ride, but it's definitely there.  Speaking as one who used to build wheels as light as possible and has now after many years realised the downside.

My Trek frame flexes a bit and feels a bit wandery, so I will be building some wheels slightly more stiff when I get round to it.  My hardtail though is stiff as hell so some more flexy wheels might be better.

Eldest_OAB who is a professional tyre and rim destroyer has only had one incident on his new wide rims (a tyre tear/spiked through).
I found my middling wide (28mm internal IIRC) to have a nice wide tyre, and more cushioning without feeling the rim bottom out.
Going back to youngest_oab's bike running 2.3's on X317's makes me realise how wobbly they were, and how much firmer I ran them on my old bike.

Have snake bites and the like gone? Answer to it all was no.

the answer is tubeless, it works real well with a wider rim and of course you’ll never get a snakebite puncture

Have snake bites and the like gone? Answer to it all was no.

the answer is tubeless, it works real well with a wider rim and of course you’ll never get a snakebite puncture

With tubeless, running low pressures you can still pinch-flat, which basically is a snakebite - which happens at the bead, and is a bit of a pain to fix - but wholly possible with some cut-up tube and some superglue.

I'm hoverring over ordering new DT 30mm rims, to replace the 22.5 rims - they're a bit heavier, and I'm still struggling to justify it!

https://www.pinkbike.com/news/talking-about-tire-pressure-pinkbike-poll.html

Some interesting results from a bigger sample size than here (pressure not width but all relates)

don't forget the heavier tyres too!

Those results are heavily influenced by the majority who don't use a proper pressure gauge, so probably don't really know what real pressure they are running.

Can people really feel the difference between a 24mm internal and a 30mm one?

17>24 okay that's an almost 50% increase, but 24>30mm is more like 25% at best and can't make much difference to the tyre profile of a 2.35 tyre.  I remember my old Mavic SLRs needing higher pressures to maintain stability in hard cornering, but they were 17mm internals.

Going to larger 2.5+ tyres, maybe...maybe, but even then.

I've got 45mm, 30mm, 26mm and 22mm, all carbon, all 32h, all laced to CK hubs, all (except the 45mm) using 2.2 rear tyres or 2.4 fronts.  I can't tell the difference between them at all.

could well be, but the low pressure revolution doesn't seem to have really taken hold across the board. Certainly would just result in rim death and a long walk in many places

"  I’ve got 45mm, 30mm, 26mm and 22mm, all carbon, all 32h, all laced to CK hubs, all (except the 45mm) using 2.2 rear tyres or 2.4 fronts. "

ok, just you are admitting you haven't tried wide tyres on a  wide rim?  say 2.5 on a 30mm..?

When I hit rock gardens or other large features at angles I can really feel the wheels deforming

Seriously?

One other benefit - a wider rim gives you a bigger volume for a given tyre - although only slightly but it all adds up. This means lower pressures are possible. But I agree - the main benefit is how the tyre behaves in cornering at lower pressures. On narrow rims they tend to squirm.

I think 30mm is more than wide enough for 'normal' sized tyres. My old 26mm Stans Flow ex gave a really nice tyre profile on my 2.4 Ardent - which are about as big a tyre as you come across. Having moved to 30mm - not sure Iv noticed much difference.

Think it depends a lot on tyre size, I've had 25, 27 and 30mm rims using maxxis 2.3 and think the ideal is 25mm for that tyre size. Obviously using larger tyres like maxxis wide trail or the new breed of 2.6 trail tyres would suit wider rims but then there's a weight penalty especially on a trail bike. A 2.3 on a 30mm rim gives a wierd tyre profile imo, the sidewall is wider than the tread and feels draggy on the rear as more of the side knobs are in contact with the ground. I've just ordered a set of dt swiss xm1501 wheels and was originally going with the fashionable 30mm versions but decided on the lighter 25mm for the above reasons.

a wider rim gives you a bigger volume for a given tyre

How can this be, the volume is dictated by the actual tyre; as unless the wider rim has a much deeper internal section (thus adding a tiny amount of volume) the actual volume of the tyre can not be changed by widening of the rim.

It may well give you a wider footprint by squaring off the side walls and therefore the treaded section of the tyre, but nothing else; if anything it will decrease (slightly) the height of the the tyre from the rim.

dt swiss xm1501

The exact wheels I have in the 22.5mm size. Great set of wheels, 28h... stiff and incredibly well built by a Swiss person.

a wider rim gives you a bigger volume for a given tyre

How can this be, the volume is dictated by the actual tyre

As the tyre is wider at the bottom at the bead, it gives the ability to fill more air into the greater internal space, it's not really the tyre but the rim+tyre combination.

“ok, just you are admitting you haven’t tried wide tyres on a wide rim? say 2.5 on a 30mm..?”

Well, I’m using a 2.4 on a 30mm rim, so you think I’d notice a difference between a 2.4 and a 2.5? 🙂  That’s 2.5mm difference in tyre width.

Also, I’m using 3”tyres on 45mm rims, so do have some experience of big tyres on big rims.

i have a set of i45 scrapers, with 3.0 tyres on, i was wondering how much smaller tyre i can go and still have a good tyre profile, i was thinking of 2.6 tyres, or ill sell them if i dont feel the difference is noticeable enough

The tyre is designed for a certain width rim. The volume maxed and pressure will be  min giving optimum performance.

The sidewall will have been designed for this too.

Anything else is a compromise.

Top riders can tell the difference.

I doubt I could. But will always pick the correct width tyre as I need all the help I can get !