Dirt bike rims... what should you know about them? What do you look for when you're checking them for faults? How do you maintain them? And what are the better brands? Well... read on.
Not all rims are designed equally. They come in various sizes, colors and strengths. Most production bikes these days come ready to race with a shiny set of alloy rims that are more than satisfactory for the majority of riders. However, over time, and without regular checks rims can become damaged.
If you want to see what a dirt bike rim looks like after being smashed to bits, take a look at my videos page and watch Seth Enslow doing his thing. Somehow I don't think they were designed for that kind of treatment, but if they aren't properly looked after that is exactly what can happen.
Once the rim looses it's true shape, it looses a lot of it's structural strength. This can be caused by hitting hard objects such as rocks or branches e.t.c. If the tire pressure is too low, you increase the risk of causing fractures or dents in the rim after hitting such objects. Keep an observant eye out for damage. Depending on how bad the area of concern is, sometimes a rim specialist can fix it, otherwise it's time to get a new one.
Another cause of rim damage that can easily be avoided is loose spokes. Spokes give a dirt bike rim it's strength, but you knew that right? Well, in that case... how often do you check your spokes for damaged or loose ones? It is vital that you check them regularly. They will vibrate loose occasionally, and if left loose they can no longer serve their purpose. A weak spot will be created and the rim will now be open to damage.
I learnt the hard way a few years ago after failing to tighten the spokes in the rear rim. A bend (or warp) appeared and then while racing one particular day the rear wheel finally gave way. It cost me around $600 NZ to get a brand new, standard excel rim and spokes to replace it. Ouch!
Checking for loose spokes is easily done by running a metal tool such as a screwdriver over the spokes. Listen for the different sound they make. They will make a higher-pitched ringing sound when tight and a dull noise when loose.
When tightening spokes, be careful never to over-tighten them. You can pull the rim out of shape and strip the thread. If you strip the thread, that spoke is a goner. You can buy proper spoke spanners or you can use a small wrench or pliers. The key to tightening spokes is to do it in small, even increments making sure they are all tightened the same amount.
TIP: Occasionally squirt a small amount of CRC or anti-corrosion spray where the spokes screw into the rim. This will prevent them seizing up over time.
If you buy a new or after-market dirt bike rim you will find they come separate to the spokes and hub. You can keep your old hub no worries, but chances are you will have to get new spokes to go with the rim. Either way, it will need to be assembled, or laced. There is definitely an art to this and it is something I have previously left to a bike mechanic for a small fee. If it's not put together properly you can kiss your money goodbye.
Where's the best place to buy dirt bike rims, hubs and spokes? Well apart from supporting your local bike shop, you can often pick up better deals online. But do a little searching and comparing of your own first and save yourself a few bucks.
When it comes to brands, most riders think... "Excel". Probably because they have won more motocross and off-road championships than all their competitors combined. They provide an outstanding range of quality after-market rims that are race-proven strong. Some other brands include Factory Effex, OEM, DID, Warp 9, BBR. There's loads of them out there but as usual you will get what you pay for. My advice is to spend the extra $$ and get something that will last.