Thoughts on Potholes... Reinforced -vs- Double-Wall Rims

[sparky]

OK... I'm building a wheel with my new, custom machined hub.

I've got a "reinforced" rim that I've got in a junk pile, and I'm wondering if I should just send it to the Wheel Master, instead of ordering a double-wall Sun Rhyno Lite for $55 or so w/ 2 day shipping.

I just want to do this one time, because it can only be done one time without grinding the inner freewheel off. Soo...

I never had any problem with my Chinese 1.5" reinforced rim, but the wall did bend when I hit a pothole. And it bent right above the reinforced part. I'm wondering if a double-wall rim is ACTUALLY going to protect me from potholes ANY MORE than a reinforced rim.

And, since I was able to repair the reinforced rim by hammering it back and jb welding the crack with multiple layers (*NOT* recommended for front wheels)... I'm wondering if a reinforced rim actually has an advantage over a double-wall rim??? If a double-wall rim hits a bad enough pothole at 20mph, that wall would seem more likely to crack, as the lower part of the wall will NOT bend outward.. so such a hit would have even MORE force on the middle part of the wall, which WILL bend.

Or am I over thinking this??

I really think it's all in the metal used. So anybody know a good 20" x 1.5" 36 hole rim? Is the Sun Rhyno Lite good enough? Or are my inclinations right, that a reinforced rim actually has a benefit, since I was never able to get one to be "untrue" from extreme use?

I need to get this shipped off to the Wheel Master like yesterday.

 

[loquin]

I really like the Sun Mammoth BFR (Big Fat Rim). A little heavier than most other aluminum rims, but pretty much indestructable. The wheelmaster built a front wheel on the 26 inch (36H) version of this rim for me, and I believe I could take it off a 5 foot curb if I had to. I know I've hit potholes at speed, and the wheel stays true. (and I'm no lightweight ... (unfortunately ))

Rating


Amazon has 'em in 20 inch for $32...
.

 

[sparky]

Dang... wish I'd seen those sooner. They look pretty sweet.

20"x2" is a bit wide, tho, methinks. The Odyssey Hazard Lite rims look pretty sweet, and they say 20"x1.75".

The rim that originally came on the bike was 20"x1.5". And I'm not too keen on making it a whole lot wider, because when I put the brake cables on there, I cut the cable too short, so I can't actually adjust the brakes any wider without getting more cable. I'd need new brakes, too, because the spring is worn out and won't spread open much further than where it's currently at. And the rim always stayed true, so I think it can handle it.

My problem was with a sidewalk that had a "tectonic plate shift", and me not seeing it until it was too late, so my front tire hopped over it, no prob... but my back wheel got hit with something like a concrete arrow, bending the sidewall of the rim.

I do not think that any rim will actually be able to stop that, but I came here to see. I was expecting more like a steel rim, perhaps??? Or for somebody to tell me that reinforced rims were just as good as any others, so I wouldn't have to buy anymore.. but I just had the Rhyno Lite shipped directly to The Wheelmaster, because it's saving me a great deal of time with shipping. So that answers that....

But a steel bicycle rim is something that I'm hoping somebody is still able to point me toward. That would be sweet!!

 

[motorpsycho]

If i were building a m.b. with 24" or 26" wheels, here's what i'd do.
I'd get a set of ACS Z rims for it (but they can be expensive)
The ACS Z rim is made of very a strong nylon composite (Dupont Zytel to be precise) the same stuff that the old school bmx skyway tuff wheels were made out of. The rims themselves are VERY strong, flexible and are known to be unbreakable.
You can bend the spokes if you really try but most of the time the rim will flex and the spokes will spring it back into shape. You can bend the spokes bad enough to bend the rim, but all you have to do to fix it, is replace the spokes and have the rim re-trued.
These rims are stronger and lighter than aluminum or steel, plus they won't bend or break like an aluminum or steel rim.
I don't know, but that's what i'd do.
here's a nice little tib-bit of info on these rims.
http://ridebikes.wordpress.com/2008/07/18/z-rims/

 

[retromike3]

Tuff Luck

Back in the time of my youth they had BMX bikes that you raced on a quarter mile track. One of the most popular wheels at that time was the skyway Tuff wheel. It was a bombproof bendex coster brake 20 inch wheel. It was very heavy but would never fail. Later they came up with a compromise it was called the Z-rim it was made out of the same material the Tuff Wheel but was laced up like a standard rim,

The main problem with this rim was the fact that the breaking surface really did not work with the brake pads at the time. They came out with a special set of pads just for the tuff wheels. Those pads did not last very long, but they were the same color as the rim so it didn't look too bad and if you're only riding the bike for a quarter-mile shot is really not too much to worry about.

I built a downhill bike that had two front tuff wheels on it. It was very fast and I would clock speeds of about 50 miles an hour down some of these hills. The main problem that I had was that I had to wait quite a while at the bottom of the hill for the smell of burnt brake pad to leave the area so I could put the bike back in my little station wagon in order to get to the top of the hill again.

I went through a new set of brake pads every other time I went down the road on that little bike. I would recommend if you were going to use such a rim on a modern bike it would be in your best interests to switch to some kind of disk or drum break, or just forget about breaking altogether.( I've been told that stopping is overrated anyway.)

mike

 

[motorpsycho]

Back in the time of my youth they had BMX bikes that you raced on a quarter mile track. One of the most popular wheels at that time was the skyway Tuff wheel. It was a bombproof bendex coster brake 20 inch wheel. It was very heavy but would never fail. Later they came up with a compromise it was called the Z-rim it was made out of the same material the Tuff Wheel but was laced up like a standard rim,

The main problem with this rim was the fact that the breaking surface really did not work with the brake pads at the time. They came out with a special set of pads just for the tuff wheels. Those pads did not last very long, but they were the same color as the rim so it didn't look too bad and if you're only riding the bike for a quarter-mile shot is really not too much to worry about.

I built a downhill bike that had two front tuff wheels on it. It was very fast and I would clock speeds of about 50 miles an hour down some of these hills. The main problem that I had was that I had to wait quite a while at the bottom of the hill for the smell of burnt brake pad to leave the area so I could put the bike back in my little station wagon in order to get to the top of the hill again.

I went through a new set of brake pads every other time I went down the road on that little bike. I would recommend if you were going to use such a rim on a modern bike it would be in your best interests to switch to some kind of disk or drum break, or just forget about breaking altogether.( I've been told that stopping is overrated anyway.)

mike

see my post above, you're a day late...lol.

 

[darwin]

Trick is to avoid the pothole. From the pic above I thought double wall meant 2 sidewalls on each side, guess it doesn't.

 

[sparky]

No doubt. I will likely stop riding on the sidewalk now. Too expensive and time consuming to deal with this wheel building nonsense.

Here's the difference between a double & triple wall rim... http://bmxmuseum.com/forums/viewtopic.php?pid=1341698#p1341698

Here's what I'd consider to be a "reinforced sidewall"...
http://en.wikipedia.org/wiki/File:Bicycle_rim_diagrams_03_.png

My rims are "reinforced sidewalls", but the reinforcement only goes halfway up the wall.... similar to the double & triple wall rims...

But the BIG difference between a reinforced sidewall & a double/triple wall rim is that the double/triple wall rims HIDE the spoke nipples. The double and triple walls are actually more like floors.

THIS is exactly what led me to post my question here!!!

The difference I see between a reinforced sidewall and a double wall rim is "the number of floors". I guess that the extra layer or two of floors would make the torque necessary to bend the sidewalls a good bit more.... but I feel that a bend in a sidewall of a double-wall rim would be a sharper bend, and far less likely be be able to be repaired.

Oh well... I'm about rimmed and spoked out. Hope I don't have to deal with anymore custom wheels for another 2 or 3 years.

 

[motorpsycho]

a double wall rim is just that.
the wall where the spokes go through is doubled with an air gap in between.
I have double wall rims on my bmx bike and they are a lot stronger than single wall rims.
BUT, in reality, single and doube wall rims can be just sas strong as each other if they are set up and built right.
a good resource for info about this stuff is to check out old school bmx web sites.
there's a ton of info on those sites that are very usefeul.
there's also a lot of older products made for bmx and racing that were extremely tough, but aren't available as new anymore.
this info would give you a name to look for, and you can usually find some of the parts on e-bay if you know what to look for.
back in the 70's & 80's when i raced and rode bmx, the products that were available then were MUCH better than the stuff that's out there now.
things these days are made cheaper, and not as strong in my opinion.
sometimes, using older parts is the way to go.

 

[5-7HEAVEN]

Trick is to avoid the pothole. From the pic above I thought double wall meant 2 sidewalls on each side, guess it doesn't.

I agree. Avoid potholes and install a front suspension fork.

I bought a set of 32-hole double-walled Alex rims w/14g SS spokes on sale. With Armadillo 26 x 1.95 tires and a year of regular street driving, I've had one loose spoke problem, that's it.

And that's a 70lb bike and 225lb man and backpack, running 4hp+ @ 44mph on pavement.

Avoiding potholes in sight, of course.