If there's one disadvantage we have as American cyclists it's our knowledge of how to ride a tactically aware road race (criteriums being another matter). Ask anyone who has raced in Europe and they'll tell you that "it's a different world over there." When to attack, how to attack, who to attack with and, more importantly, when not to, are important details many local riders are not confident dealing with.
One of the most misunderstood tactics is blocking. Until the early '70s blocking was against the rules in the US (it is unknown if this rule was ever enforced)!
If possible, always make some effort to block when a teammate is off the front in a promising looking breakaway. This does not mean physically impeding anyone but it does mean interrupting any paceline- like rhythm that might develop. Properly done, blocking is neither dangerous nor aggressive. It is most effectively done by going to the front and slowing down slightly so the riders behind will have to pass to maintain speed. This can be very effective through corners or when more than a couple of riders are doing it.
If the blocking is too obvious it will not be effective. Nor is it good to chase every individual rider or small group that foes off. Opening a gap near the front of the pack can be even more effective than blocking from the front.
Some less experienced riders may complain that "you're not doing your share". These are usually the same ones who pull the field up to every break never knowing why they can't seem to get away themselves. Pulling the pack rarely does anything to increase your chances of doing well. If you need the training great, go to the front and hammer, but don't ruin other rider's chances of successfully breaking away in the process. This "negative racing" is unproductive and makes racing less enjoyable.
It's better to bridge up to a breakaway alone or in a small group. Try starting 10 or 20 riders back and come by the leaders with enough of a speed differential to open a quick gap. Teammates can make things easier but you'll usually have to get that initial gap on your own. Try jumping hard on a short hill or at the exit from a tight corner into a cross-wind. Save energy for these strategically important sections and don't waste it pulling the field around. If the pace seems slow try to get a break going and let the pack take their time.
Roger Marquis (www.roble.net/marquis)