I am DONE with going fast down hills!

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PpPete

Legendary Member
Location
Chandler's Ford
Some bikes seem to be more prone to a "shimmy" than others.
My GPS seems to have recorded 70.4 kph yesterday on The Dean - but I don't recall any of it being particularly hairy. Will have to have look where it was after tea.
 
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Andrew_Culture

Andrew_Culture

Internet Marketing bod
Some bikes seem to be more prone to a "shimmy" than others.
My GPS seems to have recorded 70.4 kph yesterday on The Dean - but I don't recall any of it being particularly hairy. Will have to have look where it was after tea.

Mine is totally rock solid and fine until I hit about 40, then as long as nothing untoward happens I'm fine up until about fifty, at which point I get something along the lines of this happens:

View: https://www.youtube.com/watch?v=X-rkFaIPyL4
 

format

Über Member
Location
Glasgow.
For me it's all about choosing the right hill. There are some hills around where you can see everything, no side roads, fairly straight and if you know the surface well, I've no problem letting rip.

However, if it's an urban area, or I'm unfamiliar with the descent, I'll be a bit more cautious.
 

the_mikey

Legendary Member
Steel frames are notorious for developing a shimmy, it could be triggered by unbalanced wheel rims, once they reach the resonant frequency of the frame the whole thing becomes a monster. The trick is to change the resonant frequency of the frame by clinging onto the top bar or making firm contact with the frame using legs, this might detune the frame enough to kill the wobble.
 
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Andrew_Culture

Andrew_Culture

Internet Marketing bod
Steel frames are notorious for developing a shimmy, it could be triggered by unbalanced wheel rims, once they reach the resonant frequency of the frame the whole thing becomes a monster. The trick is to change the resonant frequency of the frame by clinging onto the top bar or making firm contact with the frame using legs, this might detune the frame enough to kill the wobble.

I was on an alloy frame today, it has wobbled before and a slap to the crossbar sorted it, I had no time today, I looked down to slap it and saw a 30cm high curb disappearing under my front wheel!
 
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Andrew_Culture

Andrew_Culture

Internet Marketing bod
"I am DONE with going fast down hills!"

Fibber! :thumbsup:

Nope. I am going to give it up for at least the next eight hours.
 

crazyjoe101

New Member
Location
London
Hmm, out of the three lines from the three times I was on that hill can you tell which didn't work out too well?

image-jpg.41139.jpg
None of them, apparently...
 
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Accy cyclist

Legendary Member
I knew this would descend:whistle: into a "the fastest i've gone downhill" thread!:rolleyes: Anyway i was driving down the hill i did my fastest descent on the other day when i got behind a cyclist going down it. I sat patiently behind him and looked at my speedometer. He reached 43mph and when it was safe i passed him then pulled over on the flat bit. As he passed i waved him down and we got chatting. He said that he'd reached 55mph on that hill before but he was happy with 43mph as the cross winds were bad. I went down the hill the same evening reaching a mere 36mph. Strong winds capable of blowing you into oncoming cars certainly make me cover the brakes!
 

Shut Up Legs

Down Under Member
Ah, yes. Brings back fond memories of my near-stack coming down a mountain. Nothing to do with cars, though, just me not quite being careful enough! (fast-forward to 4:30)
 

marcusjb

Senior Member
Location
Twickenham
Hmm, out of the three lines from the three times I was on that hill can you tell which didn't work out too well?

View attachment 41139
Is that misnamed on the map?

I had assumed from your post you were talking about broomfield hill, yet this is marked as sawyer's (which doesn't have any pinch points and is a pretty straight and safe descent (unless you are Fabian cancellara).

I'm lucky enough to only live 5 minutes from the park, so do get to use it often (100+laps a year).

The descent of broomfield (when riding ACW) is tricky and I have often seen the aftermath of people over cooking the corner - it's camber is very difficult and will spit you out very easily. The surface is also less than perfect.

Cars do often cross the solid white lines to overtake bikes climbing the hill, and I have seen a number of very close misses over the years.

Glad you survived the prang!
 

nickyboy

Norven Mankey
Descents I don't know, descents with a sketchy surface, descents that are wet, descents with lots of side roads, descents without clear sight lines........all these make me ease off

But give me a well known, well surfaced, dry, single road with good sight lines and I'm off. 50 down the Snake yesterday which meets all these criteria, only possible to hit this with a decent tailwind, not steep enough otherwise

I certainly wouldn't gun it where there was a decent chance of traffic pulling out on me. Drivers, perhaps understandably, don't allow for a cyclist doing 50 in their decision to pull out. For those local to me, the two obvious ones are the descent into Hayfield from New Mills (side road right at the bottom) and then the descent into Glossop after that (side road at the bottom and lots of parked cars on the way down)
 
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