eom 

1. So what width rim is ok for this tire?

2. Is a tandem the same? No jumping curbs or sliding thru corners. We just have fun. 400lbs.

Our Burley Samba has:
Front rim is unknown brand. Measures 19mm inside.
Rear is Velocity Areoheat, their info. 18.6 mm.
OPTIMAL TIRE WIDTH: 25mm - 38mm
We are running Pasela tserv 26 x 1.75. For a while we ran Powerblock 2.1. I started to have visions of the 2.1 rolling off the rim. Went back to Pasela.
Both are folding bead. Does this matter?


Ok, school me.

Thanks

beicster 

This is just an anecdote and not a definitive answer but I have clear memories of running narrow rims with 2.1" Panaracer Smoke and Dart tires on my mountain bikes in the early 90's. A whole bunch of us did. I was not carrying the weight of a tandem, but I did weigh 200 lbs and was quite careless about line choice on rooted and rocky downhills. I got hurt plenty, but never because the tire blew off.

USAZorro

No idea how any of this compares, but I have RTPs on Sun CR-18's that are on a Giant Iguana that I converted to a drop bar racing cruiser and there's no issue.

FBinNY 

With the understanding that there's plenty of fudge room at either end, here's a chart matching tire and rim widths. There are advocates for going to the extremes, both wide and narrow, but the mainstream is near the center. Use it as a guide, then pick tire width according to your weight and road conditions. (fatter/bumpier go wider).



If you want to know more, there's plenty of info in the net. Search "bicycle tire and rim width".

John E

Very true about "wiggle room" on the chart, which is pretty conservative.

ThermionicScott 

Some data points:

RTP's only seem to measure 2.1" in the real world.
Zillions of 1980s/1990s mountain bikes shipped with 2.1" tires on rims that the ETRTO would have considered too narrow at the time but revised their guidelines to be more permissive later on.

So you're probably safe with any MTB rims that aren't stupid-narrow, and as long as you don't let the tire pressure get too low.

gomango

Agreed.

I haven't had an ounce of concern with these on two different rims.

I'll check on the rims and widths when we get home from our trip to Cuyuna later today.

eom 

When I first mounted the Powerblocks I didn't give any thought to rim width. They fit, no problem right?

I have looked at the chart for rim width and tire size. There has to be a reason Velocity says 38 is max for the Aeroheat.

I am just a old guy who likes old bikes. I started working on bikes to save time and money and have been learning as I go. I will admit to having paid to have a tire changed in my past and being terrified of a quick release. My previous self and a lot of people look at a bike and see a simple item, maybe just a kid's toy. I continue to be amazed at how complex the bicycle is.

Thanks to all so far for your information. Hope for more.

kb

rhm

I'm not going to address the question of "how narrow is too narrow," but let's consider what's the disadvantage of a rim that's too narrow.

There are two, I think.

First, a wide tire on a narrow rim will have a greater tendency to deflect off to the side when cornering. As a result the bike will feel less secure on turns. I have experienced this, and it was quite alarming, but did not cause me to crash.

Second, with narrower rims you will have a greater risk of pinch flats.

To minimize both of these potential problems, you will want to run higher pressures in your tires, which will to some degree reduce the advantages of the fatter tires. But this being a tandem, I don't think this will be an issue.

ThermionicScott 

If you're really concerned, you could always build up a set of wheels with Sun Estate rims. In those earlier days I mentioned, you could infer a recommended 1.45-2x ratio for tire:rim width from the ETRTO ranges, and the Estate at 27.3mm internal width conforms to that for a 53mm tire. But you'd add some weight to get there. (I don't think I'd bother going wider than a Sun Rhyno Lite.)

eom 

I checked with Velocity. They are adamant about the Aeroheat being too narrow for RTP.

"What we tend to see on rims with tires that are too wide is the sides of the rims start to fold outward. In the early stages this just looks like the brake track is concaved but eventually the rim will crack along the length of the brake track."

Hard for me to disregard their answer.

Thanks for everyone's insight.

63rickert

I've broken three Velocity rims in exactly the manner stated. At the time Velocity was puzzled. My tires were only very slightly wider than what they now recommend. In past, like other posters, other rims have survived long periods with big mismatches.

When you change rims you will be pleased with the change in tire performance. What rhm says is completely correct. But there are more good things that will happen. It seems like a lot of trouble to go to, but it's a tandem, they always need work. And you get something for your trouble this time.

Choke 

Not only that, but for a while the hot MTB rims were cut down and re-rolled Mavic MA2/40s (done by Keith Bontrager) which are really narrow. I had a pair of those and IMO they worked great with the 1.95s of the day.

Having said that, given Velocity's reasoning for their recommendation then yeah, I'd look for something wider. And probably not something made by them, since I've never heard of any other company having that problem.

SquidPuppet

Must see photo of this bike please.

USAZorro

Here it is:

SquidPuppet

That's actually cooler than I anticipated.

I have Compass 700 x 35s on a bike and they ride freakishly nice. I'm guessing the RTPs are like riding on clouds filled with whipped cream and helium? I'm trying to justify the price tag to put a pair on my klunker.

USAZorro

I've yet to take them off-road, but there's a definite difference in feel (massive understatement) between those and 25mm tubulars when going over bumpy spots in the pavement. The bike is definitely faster than it was in MTB configuration, but slower than this. (not surprised. )

Lascauxcaveman 

Maybe you should consider getting a good bike and trying out those expensive tires? I know you're fond of your Varsinental single speeds, but there is a whole 'nother world out there, if you're willing to look.

ThermionicScott 

I've heard of that, but couldn't remember who was involved and which rims they were.

Hoop stress is a thing -- perhaps Velocity is concerned about people putting tires much larger than recommended on their rims and then inflating them to the max instead of something sensible. Whether it's an admission that the rims aren't overbuilt, or just CYA, I'm leaning toward following their advice. The good news is that there are light and fast tires in the 38-42mm realm, so new rims aren't really a necessity unless the OP is gung-ho on the Rat Trap Passes.

SquidPuppet

What is a good bike?

During the early nineties I bought a serious adult bike, a new Bianchi Giro. I did some upgrades. Full Campy, Look clipless, Scott aero bars. I wore lycra and bike shades. That lasted a little over a year. Harsh ride, bent over, chain slap, no wheelies, no curb jumping, no sliding, inner child stifled, no fun, no thanks, not me. I'm happy for the folks that love riding their road bikes.

I have given serious consideration to having a custom filet brazed frame made by Nao Tomii. He does beautiful work.

I strongly prefer the traditional look of horizontal top tubes. I like curved blades forks for multiple reasons. I like extremely slacked head and seat tube angles for the fit capabilities they offer. I like a lot of trail because I prefer a stable front end and am willing to forfeit the ultra quick steering. I like long chain stays for the balanced way my weight gets distributed over the longer wheel base. I prefer the way the longer wheel base feels during cornering and I appreciate the improved shock absorbing characteristics. High bottom brackets allow me to crank through corners, albeit at the cost of a higher center of gravity, and I'm OK with that compromise. And of course, room for big tires. For my needs, those features help make a good bike.

If I had Tomii build a frame set, it would be nearly identical to my Varsinentals in geometry. I'd choose a slender tube set for it's looks. The fork blades would be curved and extremely slender. It would have cleaner joins and weigh less by virtue of superior tubing. I'd like a sloping crown wishbone seat stay to match the sloping fork crown. That would be a great bike. But it would just be another Varsinental. And not by accident.

USAZorro

Sounds like you'd be an excellent candidate for a 40's or 50's randonneuring bike, or something like the '49 Raleigh Clubman that I hope to have on the road before much longer. A plush ride + no hernia's while putting the bike on the car carrier is a nice combination.

SquidPuppet

You know, I like wide rims, big tires, and Brooks saddles. So I'm never going to have a light bike. And I'm OK with that. I cruise and play on my bikes. They are fair weather toys. If my paycheck depended on my race results I'd be hunched over a chunk of carbon fiber just like my competitors. You gotta do what you gotta do. And since I don't gotta, I prefer a rolling sofa that can handle being kicked once in a while.