What’s the deal with rims?


Most of the ‘true’ adventure bikes use spoked rims, rather than the ligher (and fancier) cast versions. Over rough terrian spoked rims add some cushioning to the wheel, which can be desirable, but for years they have had the disadvantage of needing inner tubes. Cast rims, more like a modern car tire, don’t need a tube to contain air, though they are more difficult to install and remove. Since the spokes usually enter the area that holds air, and aren’t air type, spoked rims need a tube to stay inflated.

So you are in Alaska on the Dempster Highway when you feel the rear of your motorcycle start to wiggle more than usual. You pull off to the shoulder, thankful you are lucky to be in one of the places which have one, but are dismayed when you look at your tire and see it’s flat. Getting the bike onto it’s center-stand and spinning the wheel you see a neat hole just off the center riding line.

If you have a tube tire, you have to remove the wheel from the bike. Once off, you need to unseat one side of the tire from the rim, and remove the innertube. Once you have to tube out you need to find the hole (did you remember to mark it’s location relative to the valve stem before you started moving the tire around? Opps.) and apply a patch. After the patch has had time to set, you need to put the tube back into the tire, and then reseat the tire on the rim (careful not to pinch the tube). Re-inflate, reinstall, and hopefully the patch holds. If not, then repeat the process down the road.

If you have a tubeless tire, you get out a different sort of patch kit (I like the gummy worm version, but there are others), clean up the whole some, install the patch and reinflate.

You can see the advantage of tubeless tires.

You might be wondering, apart from that whole slight cushioning thing, adventure bikes bother with spokes. Clearly they have some disadvantages. Well, I can explain.

You are still in Alaska, and (through no fault of your own) hit a big pot hole. A really big pot hole. Minutes later you have a flat tire, and looking at your cast rim you see there is a dent along the edge, marring that perfect circle that is supposed to be your wheel and letting the air, which was supposed to stay in, out.

Or, if you have a spoked wheel, you have a couple of broken spokes once of which probably punctured the inner tube. Now, with your spoked tire, you are facing your standard puncture. Pull the tire off, fix the holes in the tube, removed the broken spokes and replace them if you have spares. Put the whole thing back together and you are golden.

That bent cast rim, though, is a problem. You can get a rock, or a hammer, and something to cushion the rim a little, and get to pounding, but that’s about it. With a couple hours work, and some luck, you can get the rim unbent enough to hold air again, but you will still need to replace it sooner or later.

How Important Is it?

I know riders, and drivers for that matter, who manage to go hundreds of thousands of miles without getting a flat. Most of them aren’t going anywhere too adventurous, but the feat is still impressive. If you are on a trip with something that has tires, you have to expect to get a flat at some point. Bent rims are much, much harder to come by, but that doesn’t mean you will never have to deal with one, even if you never leave your city or town.

If the end it’s going to be up to your comfort level on tire changing and puncture repair. If you are never planning on leaving the developed world and never plan to change your own tire regardless, then it doesn’t much matter which rim you have.

Something Else to Consider –

Recently spoked, tubeless rims have been appearing on the big adventure bikes. With the spokes offset to the edges of the rim the center remains airtight, allowing the tube to be left out. This allows the convenience of tubeless flat repair while (hopefully) allowing the spokes to hold the rim round.

Advertisements
This entry was posted in Travel and tagged , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s