The beginning of the end.
As Ariel, Fiery Cross and the other clippers left Foochow at the end of May 1866, the steam auxiliary Erl King was loading 1,108,100 pounds of tea - she sailed on 5 June, 7 days after Fiery Cross. She coaled at Mauritius on 27 June, 22 days later, already ahead of the clippers that had left before her, and arrived in London on 22 August, 78 days after sailing - taking 77 days on passage, plus one day of coaling. She was in London 15 days before the first of the clippers. Taeping, as noted above, took 99 days to get from China to London.
Newspapers, particularly in Glasgow (where many steamships were built) and Liverpool commented that steam would soon take over carrying tea from China.
The same news reports also commented on SS Agamemnon, a true steamer, as opposed to an auxiliary like Erl King. Agamemnon had just completed a record outward passage of 65 days and was on her return trip with a very large cargo of tea. She consumed only 20 tons of coal a day at 10 knots, substantially better fuel economy than other contemporary steamships - a saving of between 23 and 14 tons per day. The confidence of her owners was such that, before proving the profitability of Agamemnon in service, they were building two sister ships, Achilles (1866) and Ajax (1867).
The opening of the Suez Canal in 1869 gave a distance saving of 3,300 NM on the route from China to London. Whilst it was possible for a sailing vessel to take a tug through the canal, this was difficult and expensive. Furthermore, sailing conditions in the northern Red Sea were unsuited to the design of a tea clipper. So they still had to sail around Africa.
When the tea clippers arrived in China in 1870, they found a big increase in the number of steamers, which were in high demand. The rate of freight to London that was given to steamers was nearly twice that paid to the sailing ships. Additionally, the insurance premium for a cargo of tea in a steamer was substantially cheaper than in a sailing vessel. So successful were the steamers using the Suez Canal that, in 1871, 45 were built in Clyde shipyards alone for Far Eastern trade.
As their numbers on this route increased, clippers had to look elsewhere for their work. Costs had to be kept to a minimum - so fewer and less skilled crew were carried. Many ships had their rig reduced to barque so that a smaller crew was needed. The last race between tea clippers to catch public attention was between Thermopylae and Cutty Sark in 1872.