Achilles Tendons
If you have pain in the Achilles tendons, the tendons at the back of the ankle that connect the calf muscle to the heel. in these tendons, it usually indicates a problem in pedaling technique. Achilles tendon problems often result from "ankling" during the pedal stroke.

This is occasionally related to

• having the saddle set too high therefore forcing the cyclist to point the toes excessively to reach the bottom of the pedal stroke.
• or having your cleats set too far forward,
• or otherwise pedaling with the toes.

The farther forward the contact between the foot and the pedal, the greater the stress on the Achilles tendons.

Ankles
Ankle pain while cycling can again be the result of "ankling" while pedaling. Pain may also result from being flat-footed, in which case orthotic shoe inserts are a likely remedy.

Another possible cause of ankle pain is a bent pedal or crank which will cause the foot to wobble back and forth as the pedals turn.

Back
Back pain is usually caused by poor cycling posture. Good cycling posture is different to that required for sitting or standing. Correct cycling posture must facilitate the pedaling action, and also must enable the rider to cope with the jolts that result from road irregularities.

When riding a cycle, the back should be arched, like a bridge. If the back is properly arched, bumps will cause it to flex slightly; this is harmless. If you ride swaybacked, bumps will cause the back to bow even farther in the forward direction, which can lead to severe lumbar pain.

Some back-pain sufferers modify their cycles with extra-high handlebars so that they can sit bolt upright. This is actually counterproductive in most cases, because a straight spine has no way to "give" when the bike hits bumps. Road irregularities will therefore jam the vertebrae together, often aggravating existing back problems. The bolt-upright posture is comfortable only if you're sitting stationary on the bike abd not moving faster than a brisk walk. Riders who for any reason require such a position should use some form of suspension e.g. a sprung saddle or suspension seat post.

Feet
Foot discomfort is often the result of inappropriate footwear, specifically shoes with soft soles. It can also be the result of riding in a too-high a gear, which results in excessive pressure by the foot on the pedal.

Fingers
Numbness of the fingers is a potentially dangerous symptom, as it can often relate to carpal tunnel syndrome.  This is one of many problems which can result from bad upper body posture.

• The Two Bump Problem
  Like your bum, the heel of your hand has two bumps, with a sort of valley between.
  There are important nerves which run through this valley and it is important to avoid excessive pressure here.
  
  Beware with padding.  If you use thick handlebar grips, or gloves with too much gel padding, the "bumps" that are best able to carry weight will press through the foam, but the foam in the middle will press back at the valley. Thus, as with saddles, too much gel can worsen the problem it was intended to correct!

Wrist angle.
Numbness can also be related to poor wrist positioning. Generally, the wrist should be held so that the hand is pretty much in line with the forearm. If your hand is bent upward from the forearm, the nerves can get pinched, causing numbness.

Knees
Cycling, done properly, is much less stressful to the knees than many other aerobic activities, because there's no impact involved. Nevertheless, knee injuries do occur, again usually as a result of poor technique or position.

• Gear Selection
  A principal cause of knee problems is over-stress caused by using too high a gear.
  
• Saddle Height
  Another common cause of knee problems is incorrect saddle adjustment, particularly if the saddle is too low. See my article on Saddles for more details on this.
  
• Cleat Adjustment
  Some knee problems result from incorrect placement of shoe cleats. Everybody has a natural angle that their feet take when cycling. When you ride with plain pedals, your foot assumes this angle, and everything is fine.
  
  However, if you use cleated shoes and matching pedals, it is important that the cleat is adjusted so as to permit your foot to be at its natural angle. If your cleats are misadjusted, the resulting twist on your lower leg will affect the alignment of the knee joint, and cause problems.
  
  This is less of an issue if you ride pedals with "float" in the cleat attachment. Most newer clipless pedals offer at least some float.
  
• Lateral Movement - Chondromalacia
  The knee joint is basically a ball-and-socket joint, with the ball at the bottom of the femur and the socket at the top of the shinbone. A common cycling-related injury is called "chondromalacia", and has to do with irritation of the cartilage pad in the "socket" which provides lubrication for this joint.
  
  Chondromalacia is often blamed on lateral movement of the joint, and a common prescription is to strengthen the quadriceps muscles which run along the front of the thigh and along side the front of the kneecap. It is these muscles which provide lateral positioning for the joint.
  
• Long Cranks
  The longer your cranks are, the further your knees will have to flex on each stroke. Different riders will have different amounts of flexibility, but riding with longer cranks than you are used to can definitely cause problems.

Hands
If the skin of your hands gets sore, cycling gloves can help.

Neck
Neck problems are most often due to poor cycling posture. An occasional source of neck trouble is poor adjustment of a helmet.   If the helmet is too low in front, the rider is forced to tilt the head upward to keep the helmet from blocking their forward view.

Sharp backward bends in the neck can cause severe problems, so make sure that your helmet is properly fitted for your riding style.

Riders with a more aggressive riding position need to wear their helmets farther back than those who sit more upright.

Poorly fitted glasses can also cause this problem.

Posture
Many inexperienced cyclists adopt a posture which allows their upper bodies to be supported entirely by their bones. This has the advantage that it requires no muscular effort, but can lead to discomfort or injury when road shocks are transmitted through the rigid bones. This discomfort may affect the back, hands, wrists, shoulders or neck.
Posture faults are mainly found in three places:

1. The back should be arched, like a bridge.
2. The elbows should be slightly bent, not straight and locked.
3. The shoulders should be pushed forward so that the muscles in the front of the chest help carry the weight of the upper body. Many cyclists make the error of letting their upper spine dangle forward, held up by the collar bones.
   
   Rolling the shoulders forward counteracts the bending of the arms, resulting in the same general angle of the upper body as a relaxed, bone-supported posture provides, but with the resiliency of muscles providing shock absorption.

Shoulders
Shoulder discomfort is again generally due to faults in the rider's posture.  It can also be caused by having the saddle angle too low in front: This tends to make you slide forward as you ride, and you wind up using your hands to push yourself back into position.

If you have pain in just one shoulder, it may be due to an asymmetry. Are you bending your arms both the same amount? Are you holding one of your shoulders higher than the other?

Some people have one arm longer than the other. For these people, it may help to deliberately set the handlebars slightly askew with respect to the front wheel, turning them away from the longer arm.

Wrists
Wrist pain is often casued by poor upper body posture. It can also be caused by having the saddle angle too low in front: This tends to make you slide forward as you ride, and you wind up using your hands to push yourself back into position.