Speed Wobble from Hell

I’ve known about the phenomenon of speed wobble for well over 25 years and know that it’s not the fault of the bicycle, that it is a natural phenomenon and that it can be corrected by shifting your weight on the bicycle. A similar phenomenon can be seen, apparently, when towing a trailer in a car, or sometimes in a boat at speed.

Yesterday my younger daughter Lizzie had persuaded me to do the cycle (17 km) of the Schull Duathlon, with her doing the two runs which were 5k and 3k. You can do these as an individual or as a team. She was doing this as a part of her running training because she likes the social aspect of triathlon, having spent some years doing triathlons with considerable success.
The route climbs for about a mile or so from Schull village and then drops fairly steeply on a roughish road.
I’m pretty heavy at the moment at 15.10 and was cycling my carbon fibre road bike for the first time since my friend was ultimately fatally injured by his forks snapping last October. He died on Christmas Day.
Anyway Lizzie came in third on the run and first lady by a mile and I suppose there were about 20 teams, the rest individuals.
Off I go, not going into the red up the hill.
As I approached the top two whippets on time trial machines passed me.
Down I go into a tuck and start going downhill. Suddenly about half ways down the bike began to wobbly not mildly but violently. When it starts gently you have the presence of mind to shift and stop it. The memory of my friend’s recent death entered my mind and I was petrified. I began to lose control of the bike and it veered towards the ditch. I was braking by this stage and to my amazement I managed to stop and get off the bike without mishap. I expected to find a broken frame or a puncture so violent was the oscillation. I had a good look at the bike, tested the tightness of the wheels in the forks, and gingerly remounted, having considered jacking it in. I began again and continued the descent. A mild oscillation began again and I stopped again. I gave it one more go, a little oscillation began but by this stage I’d regained my composure and shifted forward and gripped the top tube between my knees, or crossbar, as it is in Ireland and it stopped. I was okay for the rest of the cycle though I did not descend flat out. I supposed I’d lost 2 or three minutes but we still won the team prize, ENTIRELY due to how good a runner Lizzie is. I was shaken AND stirred.
What hit me in this episode was the swiftness and the violence of the phenomenon. Interestingly my son-in-law who has a summerhouse near here and who cycles a lot, and like me is a big man, has suffered the same phenomenon on this, and only on this hill.

I’d not had a speed wobble on this bike before..

Lizzie finishing.