First, review the website below for a list of all the common ways potentially fatal bike accidents happen, and easy things you can do to greatly minimize your risk. I have been cycling for years, but even I found some situations I have not considered.
http://bicyclesafe.com/

Second, below are some very basic guidelines for group riding. I copied these out of the guidelines for a MS150 charity ride (http://bikenjb.nationalmssociety.org/site/DocServer/BikeSafetyBrochure.pdf?docID=25002)

1. Group cycling has its own form of communication. The presence of road hazards, directions, and need-to-know information is relayed through the pack of riders by gestures and words. Remember to pass all communication on to the next cyclist behind you in the group. Speak loudly and clearly.
2. The following are the most common terms you may hear in group-sponsored rides:
   1. On your Left: This means a rider is approaching your left side. Allow room to pass.
   2. Car back: This means a car is approaching from the rear. All riders make an effort to move to the right of the road in a single file until the car passes. In most states, the law requires cyclists to ride no more than two abreast. This ensures that traffic will not be impeded, and will make passing easier and safer for the cyclists.
   3. Gravel - Pothole - Sand - Tracks: Each of these messages is to alert the riders behind you of hazardous road conditions. The words are combined with the gesture of pointing to the hazard well in advance.
   4. Flat: This indicates that a rider has suffered a flat tire. Allow enough room for the rider to slow down and move to the right side of the road for repair. Offer assistance if needed.
   5. Slowing: The cyclist in front of you is slowing down. Use caution and prepare to stop. Many cyclists use the palm of their hand toward riders behind them to indicate slowing and stopping.
   6. Stopping: This indicates that a rider ahead is stopping. Do not forget to unclip from your pedals.
3. Your responsibility in a pack includes:
   1. Be aware of others around you.
   2. Communicate well in advance. Use gestures in combination with verbal commands.
   3. Ride with your head up. Look down the road; not at the person in front of you.
   4. Maintain control and speed of your bike, even going downhill.
   5. Know your limits. Crashes can occur when inexperienced riders do not have bike-handling skills to make quick decisions in a pack.
   6. Safety starts with you. Group mentality is not always safe. Expect to stop at all redlights and stop signs—it is the law! Each cyclist is responsible for verifying that the intersection is clear.
   7. Adjust your safety zone to fit the conditions of the road, weather and traffic.
   8. Always plan an escape route.
   9. Never overlap your wheels with another cyclist.
   10. Do not use aerobars in a pack.
   11. Be aware of how weather will affect your bike. Riding in wet conditions requires slower speeds and greater breaking distances.
   12. Be respectful of other riders. Help others when needed.
4. Bicycle Laws
   1. All states [similar laws in Switzerland] consider cyclists vehicle operators, and give them the same rights and duties as other drivers.
   2. Know and obey all traffic laws: The golden rule of bicycling in a group is Be Predictable!
   3. Stay right: Ride in the right portion of the rightmost lane in the direction you are traveling and leave at least four feet between your handlebars and parked cars or other hazards such as other cyclists. You may move left when passing slower vehicles or preparing for a left turn.
   4. Obey all traffic signs and signals: Avoid “following the leader” through traffic signs and signals; you are required to obey all traffic signs and signals, including stopping at red lights and stop signs.
   5. Look & signal before you move: Always scan behind you before changing lanes or making turns. A continuous arm signal is required prior to a turn or lane change (unless arm is needed to control the bike) and while stopped waiting to turn.
   6. Two at a time: Ride no more than two abreast and do not impede traffic. If a part of the road has been closed and dedicated to “bicycle travel only” you may ride more than two abreast.

Finally, I would like to add my own advise for riding in a group, especially in a paceline:

1. Ride as smoothly as possible. Any unpredictable motion (lateral movement, braking, standing up out of saddle) can cause the person behind you to crash. Riding smoothly means:
   1. Maintain a constant pedaling effort.
   2. Do not brake unless you have to for your own safety. If the group is braking, it helps to yell "braking" so those behind you have time to prepare.
   3. Lateral (sideways) movements should be deliberately slow and smooth. Never make a quick lateral movement as you may cross tires with the person behind you, or startle passing vehicles that may lead to collisions.
2. Maintain a single-file paceline. Although these are social rides, on busy roads riding next to someone side-by-side should be avoided. Save conversations for wide, non-busy roads or bike paths.
3. Drop back on the left. If you are leading a paceline and want to drop to the back, you should first look to your left to make sure there is not traffic approaching. Then, you should slowly adjust your position to the left such that the paceline can pass you on your right. You should signal to the person behind you that you are dropping back (such as flaring out your elbow), and then slowly reduce your speed. Rejoin the paceline at the back.
4. Leave enough space to the cyclist in front of you. This is based on your comfort level. New riders should leave at least a bicycle length or two between you and the rider in front of you.
5. Look down the road, not at the cyclist in front of you.
   
6. DO NOT DO ANYTHING SUDDENLY!

• patrickrd - Still going to do a ride at 3:30 as planned, but less intense
• ManBearPig - Pumping up my Villiger

• Rahul - going on a hike tomorrow..will see how my legs feel on Sunday.
• bom - I will be there but I'm not sure I will be able to do the whole route.

• Eire - Wrong sort of tyres for a Sunday ride. But good on ya for organising.
• hillseeker - Have a prior commitment, but hope to make it one of these times... Have fun!
• Johanna - Sadly, i have yet to fix my bike (it needs an overhaul!) from last week... Hope to be back out there soon. Have fun!
• dakman - sorry going to do some trail riding with Mrs...but will join in the future - also with the reduction of light in the evenings, this may become them main group ride