What do I need to know to buy new chainrings for my crankset?

First, check your chainrings (sometimes called “chainwheels”) to make sure they need replacing. In general, the rings you ride in most wear quickest and usually they’re also the smaller rings. So check those regularly.

To do this, simply inspect the teeth shapes closely. Because the smaller rings wear fastest, there’s a good chance the large rings will be in good condition, which allows comparing the teeth on the large ring with the teeth on the ring you think may be worn out. If the teeth look smaller and hooked, it’s a sign that the chainring is worn out.

However, don’t worry if a few teeth on each side of the chainring appear smaller than the others. On some rings they’re actually made that way to act as “shifting gates,” an innovation that improves shifting. As long as the majority of the teeth look full and resemble the ones on a good chainring, the ring is okay.

Sometimes you’ll feel a worn chainring after you’ve replaced the chain. There will be a roughness in the pedal stroke because the new chain won’t mesh perfectly with the old teeth. Another symptom of a worn chainring, usually on a mountain bike, is something called “chain suck.” This is when the chain gets pulled up by the worn teeth on the ring while you’re pedaling and gets jammed between the chainring and the frame. Usually, replacing the ring solves the problem.

In an extreme case, a completely worn-out ring can even allow the chain to skip when you’re pedaling hard or climbing. What happens is the teeth can no longer hold the chain under pressure and the links actually lift up and over the teeth creating an annoying and dangerous hiccup in your pedaling, which is best described as “skipping” for the way the pedals jerk forward when the chain slips.

It’s also possible to ruin a chainring by bending it while trying to ride over a log or railroad tracks. Or even by getting your pants caught in the teeth.

If you’re not sure whether your chainring(s) needs replacing, we’re happy to take a look and let you know. Chainrings vary in design and size. You can just bring your old one in for us to match up, or if you’d rather, you can look at your chainring and give us the following details:

• The brand and model and type, such as Shimano (brand) XT (model) 9-speed (type).
• The number of teeth on the chainring (usually stamped on the side; or you can simply count).
• The number of chainring bolts (usually 4 or 5).
• The Bolt Circle Diameter (BCD). This is the measurement of an imaginary circle on the chainring bisecting all the bolt holes. The best way to determine this is by measuring the exact distance (center to center) between 2 adjacent bolt holes. Then find that number on the correctchart below to determine the BCD for your chainring.

BCD chart for 5-bolt chainrings

BCD chart for 4-bolt chainring

If you have any questions at all, just ask and we’ll be happy to help!

How do I get the right bottom bracket for my bike?

There are actually 2 bottom brackets on bicycles. There’s the bottom bracket on the frame, and the component that threads into this part of the frame, which is also called the bottom bracket. To help tell the difference, the frame is usually called the bottom bracket shell and the component bottom bracket is called simply the bottom bracket, or sometimes the “BB” for short.

When you’re shopping for a new bottom bracket, you’re looking for the bearing component that screws into the frame and which the crankset is bolted to. That’s obvious because the frame bottom bracket is built into the structure and is not replaceable (except in rare situations).

If you already have a bottom bracket in your frame and it has worn out, you’ve probably noticed some grinding or metal-on-metal noises or roughness. It’s usually easier to feel this if you lift the chain off the chainring, rest it on the frame and turn the crank slowly by hand feeling for trouble in the bottom bracket or bearings as the crank turns. When all’s right the crank will turn smoothly with a slight hydraulic resistance from the grease inside.

Another test is grabbing the crankarms and pulling sideways back and forth to feel for play in the bottom bracket. If you notice play and roughness or grinding noises, there’s a good chance it’s time to replace it.

Feel free to bring your bike in for us to have a look if you’re not sure your BB needs replacing. In general, they wear out over a period of 3 to 5 years if you ride a lot and in all weather conditions, though some can run for much longer without trouble.

Special tools are required to install bottom brackets and cranksets correctly so you may want to leave the job to us. If you like to do your own work and have the tools, bring the old BB in so we can match it up.

If you’re upgrading your crankset, you need to ensure that the new bottom bracket is compatible with your frame and the spacing required by the new crankset. We can advise or you can check the manufacturer’s specifications. In most cases, it’s best to go with the bottom bracket(s) recommended by the manufacturer for the crankset you’ve selected.

When you come in to buy a replacement bottom bracket, we need to know the following:

• The brand and model of your bicycle.
• The brand, model and type of your crankset.
• The width of your frame’s bottom bracket. Use a metric ruler to measure the width between the outside edges of the frame only (do not include any of the BB). It will measure either 73, 70 or 68mm wide.
• The length of the bottom bracket axle (also called a “spindle”) measured from end to end (if it’s threaded on the ends to accept bolts, just measure to the ends of the flat portions of the axle, not to the ends of the threaded portions).

If you have any questions at all, just ask and we’ll be happy to help!

When do I need to replace my chain and how do I get the right one?

The easiest way to check your chain’s condition is by measuring it with a ruler. Rest the ruler alongside the bottom length of chain (beneath the frame) and see if you can measure exactly 12 inches between 2 pins.

If the chain is still in good shape, you’ll be able to do this. If you try this and the measurement is 12 1/8 inches or more, it means your chain is worn out and should be replaced.

Worn chains shift poorly and will wear your cogs and chainrings out faster. By replacing the chain when you notice significant wear, you’ll ensure you get maximum mileage out of your other drivetrain components (which will save you money in the long run).

While some modern chains are installed with a special connecting link that comes with the chain, most models require a special bicycle tool not surprisingly called a “chain tool,” for removal and installation. We know how all the special links work and are equipped with the right chain tools for every type of chain so you may want to bring your bike in for us to replace the chain. It’s a quick job for us in most cases.

If you prefer to do the work, please bring the old chain into the shop for us to find an exact match. If you can’t do that, the following information will help us provide you with the right model:

• Brand, model and type of the old chain, such as Shimano (brand) Ultegra (model) 9-speed (type).
• Chain length. For this, simply count the number of links on the chain.
• Type of bicycle, such as road, mountain, hybrid, etc. While this information isn’t critical, it can help if there’s any confusion on what you need.
• If you can’t tell what brand and model your old chain is, count the number of cogs on the rear wheel. Most modern bikes have 7, 8, 9 or 10 cogs, however older models could have 5 or 6. Also, you might have a beach cruiser or city bike with only 1 cog.

If you have any questions at all, just ask and we’ll be happy to help!

Should my derailleur(s) be replaced and which should I get?

Derailleurs are the small mechanisms mounted to the frame that shift the chain between the chainrings (front derailleur) and cogs (rear derailleur) when you operate the shift levers. Unless you crash, drop or abuse your bicycle, derailleurs last a long time. In fact, they can last as long as your bike with only minor maintenance, such as occasional lubrication (any time they look dry or after riding in the rain).

Rear derailleurs are more frequently damaged than fronts because they protrude from the bicycle. This means that if someone knocks over your bike, the derailleur or the part of the frame it’s attached to, can get bent. When this happens, the derailleur will not shift properly. It will hesitate shifting onto the smallest cog and may overshift throwing the chain off the largest cog. Worse, if it’s bent badly enough, on some bikes it might even get hooked on a spoke, pulled into the wheel and end up mangled.

To ensure this never happens, always carefully inspect your bike anytime it falls over or anytime the rear derailleur isn’t shifting correctly. To tell if it’s been bent, stand behind the bike and see if an imaginary straight line bisecting the cogs will also bisect both derailleur pulleys. It should. If the derailleur looks canted inward, bring the bike in for us to have a look and realign the derailleur and/or frame with our special tools.

Reasons you might want to install a new derailleur include upgrading to save a little weight or to try the latest technology. In order to provide a derailleur that will work with your drivetrain, we’d like to see your original derailleur so we can match its capacity. Or, if you no longer have the old derailleur, we need to know:

• What brand, model and type of drivetrain and shifters you have, such as Shimano (brand) LX (model) RapidFire 9-speed (type).
• The number of cogs.
• The number of teeth on your largest and smallest cassette cogs and chainrings (4 numbers in total, for example, a modern road bike could have 11 and 24 for the cogs and 39 and 53 for the chainrings).

Front derailleurs are less often damaged than rears, though it is possible to bend them by getting baggy pants or shoelaces caught in them. Still, like rear derailleurs, you may wish to upgrade to save weight or improve shifting.

We’ll need to know several things, which we can determine by seeing the original derailleur. Or, check it and provide the following details:

• We need to know which type you have: On road bikes there are clamp-on types that feature clamps that wrap around the frame. And there are braze-on types that bolt to a special mount built into the frame. On mountain bikes (and some road/cross bikes) there are top-pull types, where the shift cable runs from above to the derailleur. And there are bottom-pull types, where the shift cable runs beneath and up from the bottom bracket (where the crankset is attached).
• For clamp-on front derailleurs, we need to know the clamp size, which must match the seat-tube diameter where the derailleur mounts. The common sizes are 28.6mm and 31.8mm for 1 1/8 or 1 1/4inch seat tubes respectively. Use a caliper to measure your frame or if you don’t have one, gently close the jaws of an adjustable wrench until it just slips over the tube and then measure the distance between the jaws.
• The number of teeth on the large and small chainrings. For example, if you have a triple crankset with 22/32/42 chainrings, your large and small rings are 42 and 22. Usually these numbers are marked on the side of the chainrings. Or, you can simply count them.

If you have any questions at all, just ask and we’ll be happy to help!

When do brake pads need replacing and how do I get the right ones?

Brake pads are the rubber or composite blocks on your brakes that rub against the rims to stop the bicycle. In the case of disc brakes, these pads are inside the brake calipers and clamp against the disc rotors when you apply the brakes.

All brake pads wear from use and should be inspected regularly so that you never end up riding withunsafe brakes. Rubber and composite pads can also harden with age, something that happens to a bicycle stored for several years. In this case, you’ll notice a serious loss of braking power, which will be restored once you replace the old pads with new ones.

For conventional rim brakes, such as sidepull, linear-pull and centerpull designs, brake pads usually feature grooves in them that act as wear gauges. When these grooves are almost worn out, it’s time for new pads.

For disc brakes, when the pads are worn, braking power drops off. Weak braking can be caused by other brake problems, too, so if you’re not sure, just ask and we’ll help. Pads should also be replaced if they’re contaminated by lubricants, which ruins them.

When it comes time to replace pads, we need to know the brand, model and type of brakes they came off. The easiest brake pad to replace is the cartridge style (see photo, above), which means the pad slips into the brake shoe (the part that holds the pad) on the brake. This means there’s usually no need to make any pad placement adjustments during replacement. Cartridge pads are on most linear-pull brakes, found on many mountain bikes, hybrids and tandems. They’re also found on high-quality road bikes.

For these brake types, you can remove one brake pad and bring it in for us to use in finding the proper replacements. Then, replacing the pads is as easy as removing the old ones and installing the new ones (being sure to match direction).

For other rim-brake types, it’s more difficult to replace the pads because you must remove the entire pad and holder, which usually means realigning the brake shoes. Because there’s a real risk of compromising your braking power, we recommend you let us replace the pads on these models. If you’re handy with tools and understand how to correctly align the brake shoe to ensure optimum braking and no squeaking, it’s not a difficult job. Install one pad at a time so you can refer to its partner to see how the new one should be adjusted.

Disc-brake pads (photo, right) are usually popped out and replaced by hand, however, this varies according to the design. Please ask us for advice when you pick up the pads, check your owner’s manual or visit the brake-manufacturer’s website for complete information.

If you have any questions at all, just ask and we’ll be happy to help!