Used Bike Guide – Wheels & Suspension

Filed under: Buyers Guide |

Suspension

  • Ask the owner how long it’s been since the fork seals have been changed (miles and/or years.) They should probably be changed every 15-20k miles. Replacing them is not necessarily a complicated fix, but it is if you don’t have the right tools, and most people don’t. (Approximately £100 of parts — fork bushings usually get done at the same time — and 2-3 hours of labor.) Straddle the bike, grab the front brake, and push down vigorously on the forks. They should go down and come back up with some resistance. Do this a few times. Inspect the chromed fork legs. [1] They should a) be smoother than a baby’s bottom with absolutely no scratches, nicks, or roughness, and b) be utterly and totally devoid of little oil droplets. (Some nicks/scratches/gouges/surface rust can be polished off, but if they can’t, new fork legs can be expensive. Have a professional mechanic advise you on what the prognosis is.) If, after bouncing the forks, you see little rings of dirt, that’s probably fine, but wipe them off with a rag and bounce the front suspension a couple more times. Not good if you see oil left on the fork legs after you do this.
  • Check the steering head bearings and swingarm bearings as mentioned in the section on centerstand checks, below. (If the bike doesn’t have a centerstand, you might be able to use a jack or work stand to raise the bike off the ground, but be very careful not to damage a bike that you don’t own.)
  • The suspension should move up and down almost silently if you bounce it up and down. Clunking or squeaking noises are bad. Binding is very bad. Run away.
  • Suspension fluid needs to be changed every year or two, as it tends to break down and thin-out over time. Ask the owner how long it’s been since the fork oil has been changed. (The suspension oil in the rear shock of most bikes isn’t generally user-serviceable, but should be changed periodically by a professional suspension shop nevertheless.)
  • Get someone to stabilize the front of the bike, you stand behind it. Push down on the bike’s grab rail (or passenger seat), hard. The bike should spring back up, but with a little resistance. If you don’t feel any resistance at all (like you’re just pushing down on a spring), it’s time to replace the rear shock. (Reasons: either a seal has failed inside the shock, or the oil has broken down so much that it doesn’t provide useful resistance.) Around £350 from a dealership, plus 3 hours of labor to install it. If you’re not sure if you’d know a blown rear shock if you felt one, don’t worry about this one. But do this to all the bikes you look at (including new bikes at dealerships) and you’ll know what a rear shock should feel like.
  • As noted in has it been crashed?, check to make sure the fork tubes are straight (not bent) and parallel (not twisted). Sight down them and pay particular attention to the chrome tubes.
  • Certain premium aftermarket suspension units (Penske, Ohlins, Fox, Race Tech) offer substantially increased suspension performance and are fully rebuildable. Expect to be asked to pay a little more for these units These units also tend to be able to go longer before needing service compared to stock suspension components. Aftermarket rear shocks often have remote reservoirs (typically a cylinder “piggybacked” to the main rear shock body or attached to the frame and connected via a hose), though since many late-model high-performance bikes come from the factory with remote-reservoir shocks it pays to do a little research to find out whether the bike you’re looking at came with one stock, or had some money put into upgrading its suspension.

Wheels

  • Look carefully around the circumference of both sides of both wheels and look for dents Around £100 (each) to get them straightened, plus labor to get them off the bike, the tires off, the tires back on, and them back on the bike. Ugh! It’s usually easier to tell if the wheels are dented when they’re spinning. So get them up in the air and spin them, if possible. Remember to check both sides. More on wheel damage at the end of this section.

Check the speedometer/odometer operation… there are two common designs of this system… if the bike has a cable that goes from the front axle (usually on the left side) up into the instrument cluster:

  • Get the front wheel off the ground spin the front wheel as fast as you can and see if the speedometer registers anything. If the speedo needle doesn’t rise, check to see if the trip odometer’s 1/10th mile digit has moved after the wheel has spun for a while. If it hasn’t, the speedo is probably disconnected or just doesn’t work.  If your bike doesn’t have one of these cables off the front axle, the bike’s speedometer/odometer is probably keyed off the countershaft (transmission output)…
  • Get the rear wheel in the air, start the engine, get the bike into second gear, and let it idle… the speedo needle should rise a bit, and the odometer digits should scroll slowly. If it doesn’t, the speedo/odo is disconnected or just doesn’t work.
  • If the speedo/odo doesn’t work, it’s hard to know how many miles are on the bike, since you don’t know how long it hasn’t been counting off miles. Run away!
  • Again, if you can get the wheels in the air see if the wheels spin freely. Wheels that drag could be either blown wheel bearings or dragging brakes. Some brake drag is normal, so examine this on a number of bikes and you’ll know when something is out of the ordinary. (In general, though, wheels spun fairly hard should spin for a couple of seconds before stopping. Rear wheels won’t spin as long, since they’ll be giving up some of their energy towards overcoming chain/belt/shaft friction.)
  • If the bike doesn’t have a centerstand, and you’re feeling physically up to it, put the bike’s sidestand down and pull sideways on the handlebars or the rear sub-frame to get the bike to pivot on the sidestand and lever a wheel up into the air. This is a little dangerous — it’s very easy to drop the bike! — but not too hard if you’ve had some practice. It’s the only good way to get wheels in the air without a swingarm/front-end stand or a centerstand. It is highly recommended that you have a friend on-hand to help with this.
  • If the bike has spoked (rather than cast aluminum “mag”) wheels, check to make sure that the spokes are all there and wiggle them to make sure they aren’t loose. Loose spokes are a sign of neglect.
  • If you can get the wheels into the air, spin them, and hold something rigid against the spokes as they turn — the handle of a screwdriver works well for this. (Careful not to scratch the spokes — you don’t own the bike yet!) The pinging sounds that the spokes make as they strike this object should sound roughly the same, since, ideally, they’re all under the same tension. A change in pitch indicates spokes of different tightness. Easily fixed, but a sign that regular maintenance hasn’t been performed.

Magnesium or carbon-fiber wheels require excruciatingly careful inspection. (And their presence may be a good indication that the bike has been raced.) These types of wheels are extremely lightweight, but they tend to crack rather than bend, and cracks can lead to sudden and catastrophic failure. If you’re buying a bike with magnesium or carbon-fiber wheels, spend some extra time examining the wheels to make sure there are no cracks. (Unless the seller tells you that the wheels are magnesium, it’ll be hard to tell, since magnesium and aluminum wheels both look the same when they’re covered with paint.) Wheels made by “Technomagnesio” or “Marchesini” are likely to be magnesium. Carbon-fiber rims are usually unpainted, as the first law of aftermarket motorcycle parts is, “Thou shalt show off thy pretty carbon fibers whenever possible.”