Today marks the 85th anniversary of Barbarossa, a massive land invasion that was led in many places by small groups of guys hanging on to motorcycle sidecars.
The 1920s German Reichswehr, officially restricted from the possession and use of armored vehicles and tanks but still well-aware of the successful factor of speed in military operations, became enamored with motorcycle troops (Kradschützen) to augment other Schnelle Truppen (fast troops) such as horse cavalry and bicycle troops, the latter retained from the Great War.
Equipped with assorted BMW R75 and Zundapp KS750 bikes, augmented by a wide variety of DKW, NSU, Triumph, and Victoria models, the Wehrmacht had a reported 200,000 motorcycles to draw from by 1938, with later captured French, Czech, and British models added soon after.

Besides platoons of dispatch riders assigned at divisional levels, Kradschützen Battalions, made up of two (later three) full rifle companies all mounted on bikes, backed by a weapons company with light/medium (5cm and 8cm) mortars and 37mm Pak 35/36 anti-tank guns, were stood up and assigned to the first 20 panzer divisions.

Thus, the 20 short-lived assorted Kradschützen Battalions were confusingly numbered 1st, 2nd, 3rd, 6th, 7th, 8th, 10th, 15th, 16th, 18th, 20th, 22nd, 34th, 43rd, 55th, 59th, 61st, 64th, 77th, and 79th. Meanwhile, Waffen SS Panzer divisions had their own respective battalion of motorcycle troops.
Entering into the war, such battalions would have 827 men and 182 motorcycles (149 with sidecars). The “extra” personnel and a Schutzenkompanie (rifle company) were carried and manned a series of 44 light cross-country patrol cars (Kfz. 2/11/12/15/18) and a mix of 50 light and medium trucks. Carrying a lot of firepower in a little package, each motorcycle battalion would have 55 light (MG34, etc.) and 14 sustained fire heavy machine guns at their disposal, allowing them to rapidly ambush or break contact and split as needed, as should any fast-moving recon or raiding force. This would change several times over the next couple of years, and it seems almost no battalion was the same as another, with minor differences in equipment and TOE.
The early spearheads of the blitzkrieg, as noted by the British in late 1940 after the Norwegian campaign, would consist of:
Two or more motorcycles with sidecars, carrying a driver and 2 machine gunners. About 5 kilometers behind them would be a bicycle patrol of from 30 to 60 bicyclists, armed with rifles, machine guns, and hand grenades. A few kilometers behind them came a truck towing a light field piece and carrying several heavy machine guns, with a crew of about 20 men. Behind them would be the rest of the company of about 150 men, usually traveling in commandeered cars and trucks. These latter troops were armed with rifles, automatic rifles, light and heavy machine guns, hand grenades, etc., and were followed by soup kitchens and commissary supplies. At dark, the main company would stop, and the advance patrols of motorcyclists and bicyclists would fall back to join them.
Epically, a Waffen SS Kradschützen element of Das Reich under Capt. “Fritzy” Klingenberg managed to slip into Belgrade during the invasion of Yugoslavia and capture the city days ahead of the main force. Such troops then proved effective in rushing ahead during the Greek campaign.

1941. April 18. German motorcycle troops arrive along the railway line after breaking through the Servia and Olympus mountain passes
The thing is, as Kradschützen were sent to North Africa, poor roads and desert mud were not the friend of the motorcycle cavalry, which was only compounded in June 1941 when the Wehrmacht entered Russia.

As dirt roads in Western Russia in the summer gave way to mud paths in Central Russia with the snows of winter, it was the Krad troops that made it closest to Moscow, with the motorcycle battalion of the 2nd Panzer Division on 2 December 1941 making it briefly to the town of Khimki, just five miles from the administrative edge of Moscow and about 12 miles as the crow flies from the Kremlin.

High Water Mark of the Wehrmacht German units penetrate to within 19 kilometers of the Kremlin during the Battle of Moscow, December 2, 1941, by Howard Gerrard
By 1943, the bike troops would be replaced by panzer grenadier regiments and Sd.Kfz. 251 armored half-tracks, and by 1945, those troops were further replaced by the humble bicycle-mounted groups, the Truppenfahrrad/Fahrradtruppen.