Your bottom bracket isn’t the most exciting part of your road bike, which makes it easy to ignore until something is wrong with it. However, it’s a very important part of your bike, so in this article, we tell you a little more about this essential yet relatively uncelebrated component.
What is a bottom bracket?
Your bottom bracket connects your cranks to your bike in such a way that they can rotate freely as you pedal and put power into the drivetrain. It is located in the bottom bracket shell which is where your frame’s down tube, seat tube and chain stays all come together. A bottom bracket typically contains bearings that enable the crank’s spindle to rotate. Shell and spindle widths vary depending on the type of bottom bracket.
What’s the big deal?
If your bottom bracket is working well, you can pedal smoothly with minimal resistance. That means the energy you apply to the pedals gets transferred efficiently to the bike.
Looking back over time, there have probably been as many different bottom bracket designs as there are bike brands; and some bike brands have even been known to come up with their own proprietary bottom bracket designs.
Modern bottom brackets tend to come in two general types: threaded and press fit.
Threaded bottom brackets
Threaded bottom brackets can only be used with frames that have a threaded bottom bracket shell. This is because threaded bottom brackets must be screwed into the frame. These bottom bracket’s bearings are typically held in place within cups.
What’s tricky about threaded bottom brackets is that not all threaded bottom brackets are created equal, which means that different types of threaded bottom brackets can’t just be swapped for other types.
For example, two common threaded types are Italian or English. Both sides of an Italian standard bottom bracket are right threaded; whereas English standard bottom brackets have opposite threading, like your pedals do. The advantage to the English design is that the drive side does not come loose through the forces of normal pedaling action like it tends to on the Italian version.
The good news about threaded bottom brackets is that they are relatively easy to install and maintain.
Press fit bottom brackets
Also known as threadless bottom brackets, press fit bottom brackets get, well, pressed into your frame’s bottom bracket shell instead of threaded in. They are effectively cartridge bearings pushed into the shell, and their design often allows thicker crank spindles, which some riders experience as stiffer and more efficient.
Some examples include BB90/95, PF86/92 and BB30. BBright and BB386. Special tools may be required to press the bottom bracket cups into your frame during installation and likewise to remove them again should you ever need to do so.
Square taper bottom brackets
This once very popular type of bottom bracket combines the bearings of the bottom bracket and the crank’s axle together into one removeable part. The cranks affix onto two square tapers on either side of the bottom bracket.
Square taper bottom brackets are effectively a specific kind of threaded bottom bracket. They are frequently found on older, vintage bikes, but are still on some more contemporary bikes.
What can go wrong
When your bottom bracket is poorly adjusted, it may develop play or a wobble, causing less efficient transfer of energy from you to your bike.
Another common problem is that when bearings get contaminated with dirt and water or wear out, there is more friction in turning the cranks, so it feels harder to pedal. Sometimes the bearings actually feel rough when you spin them; other times, you may hear and/or feel a click or two with each pedal stroke, especially under higher loads.
It is important to maintain your bottom bracket. If you have a threaded bottom bracket, remove it periodically and refresh the anti-seize compound that keeps it from getting permanently stuck in your frame.
And no matter what type of bottom bracket, check your bearings regularly to keep them running smooth. Loose bearings in some types of bottom brackets can been taken apart and cleaned and re-greased; whereas in cartridge-type bottom brackets, you’ll simply replace the cartridge bearings when they go bad.
You can make your bottom bracket last longer by carefully cleaning your bike. Never spray high pressure water directly at and around your bottom bracket as it will eventually penetrate seals compromise the integrity of the bearings.
Lots of different bottom bracket standards mean there are lots of different tools for installing and removing them. If you don’t have the proper tools and skills, you may need to take your bike to your local shop to help you fix any bottom bracket issues.
Before your next triathlon, make time to plan and practice your transitions. With some strategic preparation and practice, you’ll save time, energy and stress as you switch from swimming to riding and from riding to running. Read on for tips about how to make your transitions easier and faster.
Get to Know Your Transition Areas
Before races, thoroughly survey each transition area. First, figure out where your gear will be, then plan your routes for efficiently getting in and getting out. Better yet, practice those routes so that on race day you don’t have to think about where to go when.
Prep your Gear
Space is limited in a transition area so only bring the gear that you’ll actually use; it reduces clutter as well as the chance of grabbing the “wrong” gear. Think about the order in which you will don gear for each leg of your triathlon. Strategically place items with the furthest away being the ones you’ll need last and the nearest being the ones you’ll need soonest.
For example, set your helmet on your aerobars upside-down and with your sunglass inside because you will first put on your glasses followed by your helmet before grabbing your bike. And instead of putting on your cycling shoes in the transition area, you can clip them into your pedals. Don’t actually slip them on until you have hopped on your bike and are rolling out of the transition area.
Be Efficient in T1: Swim to Bike
Figure out in advance up until what point you will be able to swim and where you will have to start running. Since you’ve already dialed in your route, you can concentrate on starting to strip your goggles and wetsuit on the fly. Have the top of your wetsuit down by the time you get to the swim-bike transition area.
After you get to your gear, remove your goggles, don your sunglasses and helmet and move toward the exit. Know at what point you will hop on your bike, but be flexible in the moment; it may be worth running a little farther to escape transition area congestion.
Keep Your Focus in T2: Bike to Run
Remove your feet from your shoes as you approach the second transition area so that you pedal the last few strokes with your feet on top of your shoes. Know ahead of time if you will have to rack your own bike or can hand it off to a volunteer.
Remove your helmet and set it down so that you can quickly put on your running shoes and cinch lace locks. Then grab your race nutrition, number and hat and start running. You can stash your gels and adjust your number on the fly.
Practice Makes Perfect
While you are tapering for your triathlon is a great time to practice your transition skills. Since you’re no longer putting in the big training hours, you’ll have more time to focus on and improve skills. Set up a mock transition area and practice repeatedly switching between swimming and riding and between riding and running. Measure your progress objectively by timing yourself or ask a friend or coach to time you.
Watch and Learn
Ask others to observe your practice transitions and tell you what they see. Then watch other more experienced triathletes practice their transitions and copy what they do well.
Switching from using round chainrings to ROTOR’s Q-Rings is easy, but it does require some initial setup followed by a transition period for full adaptation.
Optimum Chainring Position (OCP) is what allows you to vary the rotational position of a Q-Ring, thereby enabling you to adjust it to the precise point where you deliver maximum power during a single pedal rotation.
ROTOR suggests the following initial OCP setups by discipline:
- Road: Position 3
- Triathlon and TT: Position 4
- MTB: Position 3
Because Q-Rings use leg muscles differently than round chainrings, your muscles will need time to adapt to the new, more efficient way of pedalling. Adaptation is a gradual process covering four stages with each stage taking between one day and one week. Most riders will require at least 10 hours of pedalling time to make the full transition.
In stage 1, you will learn to pedal more efficiently. Pedalling may initially feel different, and you may find yourself turning the pedals at a faster or slower rate than your usual cadence. Don’t worry about any initial jerkiness – it will smooth out over time.
You will start to feel more capable and more powerful in stage 2, and your spin will improve on climbs. Many who suffer knee pain will start to notice it less – assuming their OCP is correctly adjusted.
Stage 3 + 4
Stage 3 will bring improved biomechanical efficiency, which produces a smoother pedal stroke due to fuller activation of muscle groups. You will be creating more power than with round chainrings. If you experience no issues during this stage, you have correctly set your OCP and are onto Stage 4 of adaptation. Those encountering issues should read on for further OCP setting instructions.
If you experience the following symptoms, you are arriving at the max chainring diameter too late because your OCP number is too big, and you should reduce your OCP by one setting:
- You accelerate and sprint easily, but have difficulty maintaining speed.
- You feel pedalling resistance too late in your pedal stroke and/or you are hyperextending your ankle.
- You need a lower cadence to be comfortable.
- Your sit further forward than usual to pedal comfortably.
- You are comfortable pedalling while standing, but not while seated.
- You have new pain at the back of your leg behind your knee.
On the other hand, if your OCP is set too low, you will find yourself arriving at the max chainring diameter too soon during your pedal stroke. You should increase your OCP setting by one if you experience the following:
- You find it easy to maintain a steady speed but have difficulty accelerating and sprinting.
- You feel pedalling resistance too early in your pedal stroke and/or you are hyperflexing your ankle.
- You need a higher cadence to be comfortable.
- You sit further back than usual to pedal comfortably.
- You are comfortable pedalling while seated, but not while standing.
- You have a new pain at the front of your knee.
Once you’ve got your OCP correctly adjusted, it’s time for stage 4 and final adaptation, which comes naturally with more cumulative pedalling time using Q-Rings.
A few final setup notes
Different bikes may need different OCPs – don’t assume you will use the same position on each of your bikes.
Adjacent chainrings in multi-ring setups may require different OCP’s.
Road Q-Rings and QXL have five OCP points while MTB Q-Rings have three OCP points.
If you are using a Micro Adjust Spider (MAS), your number of OCP points is effectively doubled because it reduces the angle between OCP points by 2.5 degrees, thereby offering micro adjustments. In this case, you should adjust your OCP in 1/2-step increments.