Any Thoughts on Rim Width?
 

I have a cyclocross bike (Wayzata) that I love to ride for general riding on roads an paved and unpaved trails. I am using 32mm tires and my question is this: What difference does a slightly wider rim make in terms of safety/performance?

I have used a set of road rims (narrow) for this application and the 32s are within recommended limits for the rims, but only just barely. Making turns at speed, it seems as if I can feel the tire sidewall flex.

Alternatively, the same width tires on a slightly wider Mavic A319 rim creates a much different tire/wheel profile and feels more stabile. I am very happy with this combination so far. (Minimum width tires for these rims is 28 I believe). There is almost no weight difference between the two tire-wheel setups.

I note that HED is marketing slightly wider rims even for road tire profiles, touting supposed performance benefits. I was just wondering if anyone has experimented and/or put any thought into this? Does the rim width really make the difference I think it does?

I can't talk about the specific rims you mention, but in my experience, rim width hardly makes any difference at all. I weigh about 240, so i favor wide tires. On several sets of rims over at least 20 years, I've run tires from 23 to 41mm without any problems related to width. The wider TIRES make a big difference, but I can barely feel the difference between narrow and wide rims. Initially I worried that the big tires might squeegee around on the narrow rims, but with reasonable pressures (only around 65-70psi with 37mm Paselas), they're stable and secure.
I do nearly all my riding now on 35mm tires on my "fast" bike and 37s on my tourer. Sometimes I put 27mm Roly Polys on the first bike, but to me, the big sacrifice in comfort isn't worth a relatively tiny increase in speed (full disclosure: I'm 65. Your priorities may be different).

As long as the tire fits that size rim, Sheldon Brown posted a chart on this years ago, he states on the same page about too wide or too narrow, and I will not bother to repost that here. The primary reason for one tire over another is you need a wide enough tire so that with your particular bicycle, rider and load you can get a high enough pressure in the tire so that it doesn't squish down more then about 15%. Rim width would then be based on the required tire width. Although there is another thing to concern yourself with and that is that the frame and brakes will open far enough to accommodate that width tire.

There are those who claim it makes a big difference, that a wide tire is more stable on a wider rim. I don't have enough experience with wider tires to argue one way or the other.

The wider rim IMHO and observation makes for a flatter tire surface. I run thinner Mavic rims with 2.1s and get a more rounded tire shape. I also have Sun Rhyno Lites with 2.1 that seem flatter. Flatter gets better traction in loose graveling trail. Rounded seems to hug corners better on hard pack. I'm 220 and ride MTB only. This time of year in the desert SW hard pack is most everything.

Yes.

Last autumn I had a new wheelset built for my commuter (which has disc brakes) using the 23½ mm Velocity VXC disc specific rims. (They have no surface for rim brakes.)

I noticed the difference immediately with my 28mm three-season tires. When I put on my 38mm studded snow tires, they also felt different than the year before. There seemed to be more rubber on the road, a flatter, less rounded profile. The additional volume also meant I could run at a reduced pressure, which improved the ride.

Carving corners with studs just isn't in the cards, but the bike did seem to corner better last year, possibly due to the beads not being quite so pinched together.

I really like the difference when riding my 28mm three-season tires. This spring it's been like a whole different bike.

Would I recommend replacing perfectly good rims with wider ones? Probably not. Would I recommend using wider rims when it comes time to rebuild or replace? Certainly.

When it comes time for new wheels on my other bikes, I'll be switching from Aeroheads to A23s.

One of the things I noticed on MTB's- Is that rounder tyres are faster on Hard Pack. Not so much the hard pack but the South downs way (a 100 mile trail along the top of the downs) has a varied surface from mud to loose scree- to hard pack soil and plenty of Grass. When you hit that grass- with a flat Knobbly tyre it gets to be hard work. The exposed side knobbles grip the grass and cause drag. With the rounded tyre- you get grip on all surfaces except slippery rock or Tree roots and more important- in mud and scree you get below the gloop to the hard surface below and then get grip. But then I normally use 1.8 to 1.95 tyres and only use the 2.1's in the summer when the ground is rock hard and I need some suspension.

I only run one width of rim on the road bikes and only use 23's so can't comment. But run 20psi lower that normal and drag goes up but grip with the flatter tread is increased. Never noticed any difference in handling though till the pressure goes way down.

My only experience with wide tire/narrow rim was not good, and it was with some cross tubulars. Last fall I hoped to get better winter performance, so I put some Vittoria 32 mm diamond-tread tubulars on standard tubular rims. The tire stayed on, seemed to be well-supported, and generally didn't do anything wrong. What I lost was the ability to remove/install my wheels without deflating the tire and pumping it back up! The brake had to be adjusted so it would grip the brake tracks well. The brake QR is designed to open up to release up to 28s (it seems). When I thought I would get some wider tires for my tour this summer, I decided on CR18 rims rather than Open Sport, Open Pro, or Aeroheads, just to address this issue. The wider brake track requires the brakes to be set wider, so when the QR opens, the inflated tire should be able to fit between them. At least I hope so!

My wide clincher wheels should be ready any day, so maybe in a week I can provide some on the road feedback. I'll be getting Pasela TGs for them.

My commuting bike uses 559 wheels. When I decided to convert it to disc brakes, I bought an inexpensive set of wheels that use Sun DS2-CX rims. Getting my 28 mm wide Conti Ultra Gatorskins on and off these wheels is so tough that I've been threatening to rebuild them with Velocity rims ever since.

Some rims and tires just don't seem to like each other. I think what happens is that even though a wheel is 559mm it's really 559 ± a certain tolerance,
if you get a rim that is at the large end of that tolerance and a tire at the small end of that tolerance, they can be a real son of a gun to get on and off. I saw the rim strip sticking out of one tire, so I need to pull it off, but those tires were hard going on, so I have been putting it off. Really windy out today, so I may tackle that one, instead of riding :eek:

Same experience here. I think there is a thinner line of contact. I can also hang on the high side of a trail where it is compacted and stay out of the loose bottom.

I don't think it's usually the rim diameter, it's just that the valley in the middle of the rim isn't deep enough on some rims. I used some Rox ultra thin rim tape that made things a bit easier, but it only lasted a few months, then started wadding up and moving. I tried Velo Plugs, but the holes in this rim are large enough that I had to use the larger yellow Velo Plugs, and I couldn't get the tires on at all. I'm using some fairly thin stretchy type rim strips now, but it's a serious battle, even with my VAR lever. you know when you have to use a lever to install the first side of a tire, it's going to be a struggle to get it on. And getting it off is even tougher. Back when I had regular rim tape on the wheels, I had to dig it out first to get the tires off at all.

It doesn't take much of a difference, but yes, the valley could be either too shallow or not wide enough, it's almost funny though, you can take the same rims, same rim strip, and with one tire you think there is no possible was it will fit on there, another model or brand of tire, and it goes on smooth as can be. The Kenda tires on the steel rims on the road bike seem to be about 2cm too small, yeah they took levers to get them on there. Noticed part of the rim strip sticking out on the front now, so I need to take that ^%$#!@* tire off again to fix it :notamused:. Tomorrow it's supposed to be a nice gentle rain all day so I will sit in the garage and pull it apart and fix it. If the number of tires that fit 27" rims wasn't so small, I would try a different tire, may still. I hope to get different rims over the off season so, the tires may fit those better. Debating though, about getting some low priced 700C rims and putting those on, brake pads have about 5mm of adjustment, so they will fit easily enough. I wonder if by 1975 some bicycle manufacturers realized that the move from 630mm to 622mm rims was inevitable and started lowering brake bridges a few mm to allow for both sizes.