Have I lost my bottle???

[Paulatic]

40 mph on a push bike hmm mad I think.

thanks for the advice/in depth thoughts

madness dont need much comment just DONT do it! Like those silly so and sos on motor bikes doing 100+ ( and end up creamed)

I fail to see how you equate a cyclist at 40mph with a motorcyclist at 100mph. There's 60 mph of difference there.
On a couple of hills, within 5mls of me, I will always be in excess of 40mph on them unless being held up by something. Climbing has to have its rewards or why bother?

[Vorpal]

madness dont need much comment just DONT do it! Like those silly so and sos on motor bikes doing 100+ ( and end up creamed)

You've never gone that fast? Or close?

I'm pretty cautious, and I've done it.

If it's mad to go 40 mph, what do you suggest is a good maximum speed? 20? 30? Where do you draw the line and why? Does it make any difference if you are on an alpine descent?

[pwa]

Keeping your speed to less than 40mph on an alpine descent can be positively dangerous, requiring constant braking and heat build up in the rims. What is a safe speed depends on circumstances. Personally, I begin to feel uneasy at 50mph even if the road looks good ahead. But I need to be happy with the stability of the bike to do that sort of speed.

[mercalia]

madness dont need much comment just DONT do it! Like those silly so and sos on motor bikes doing 100+ ( and end up creamed)

You've never gone that fast? Or close?

I'm pretty cautious, and I've done it.

If it's mad to go 40 mph, what do you suggest is a good maximum speed? 20? 30? Where do you draw the line and why? Does it make any difference if you are on an alpine descent?

the most I have ever done is 30 not more and that felt too much. I would want some thing with more mass like a m/c for 40+ .The idea of an alpine descent would be no thanks

[oneten]

In view of the number of times I've come off lately ( thankfully none of which were going down hill at speed) I'll be keeping my speed well down even though it can be immensely satisfying to set the speed limit sign off sometimes on one particular hill I won't mention!

[Paulatic]

the most I have ever done is 30 not more and that felt too much. I would want some thing with more mass like a m/c for 40+ .The idea of an alpine descent would be no thanks

Admittedly it's a long time since I've ridden a motor bike but if I had to choose between an old BSA Bantam and my Trek Domane for getting down a twisty hill quickest I'd choose the Domane.

I'm not sure what type of cycle you are riding but if you haven't tried a well built carbon frame with modern brakes then maybe you should. Yes I do over 40 with my older bikes but for building confidence at speed the Domane wins hand down.

[reohn2]

Tonyf33
IMO it sounds like the bike is resonating with the road surface.I don't know the answer other than keeping a close eye on road surfaces in the future.
I've never had a speed wobble so bad but I did once have a bike that didn't like Marathons and hands off would start to shimmy almost immediately,a change of tyres to Gators cured it.

Mercalia
I can understand you not wanting to exceed a speed you aren't comfortable with but many many people exceed 40mph on bicycles in perfect safety.
Some people feel and are safe in excess of 50mph,myself included.
It depends on roads,traffic,knowing your limits and your experience/ability.
To describe 40mph as mad,is mad IMHO .

[MikeF]

Mercalia. 30 mph is about the max I travel and then only on roads where I know the surface is good and I have good visibility of the road ahead. That does not happen very often as roads around here are often twisty and surfaces bad. So you are not alone in your caution.

[Ellieb]

Getting your weight further forward appears to be common advice. Not tried it myself.

[Paulatic]

Something like this do you mean?


Whilst looking for a pic I came across David Moulton bike blog.
Davesbikeblog.squarespace.com

He has this to say about shimmy and descending speed.
Quote "
I have written here about “Shimmy” or speed wobble. It is a subject that gets discussed over and over on forums all over the world. It has occurred to me that these bikes with the shimmy problem are often the same well known brand of bikes that the pros use in the Grand Tours and other races throughout the season.

None of the pros experience speed wobbles, there would sure to be a video of it if they did, especially if they crashed. It has occurred to me that the fault is not with the bike, it is with the rider, and the way they have their bike set up. Or rather the way they position themselves when descending.

The pros have their bikes set with the bars set low in relation the saddle. Their weight is therefore more over the front wheel, especially when in a low tuck aero position.

If a person buys this same bike and sets it up in a more upright position because his physical limitations do not allow him to ride like a pro. They should then accept the limitations in the design of the bike which after all is designed as a racing bicycle, and if it develops a speed wobble at 45 mph. the rider should consider either a change of position or keep the speed below 45.

You will notice the pros descend by moving forward on the saddle, or sometimes squatting down on the top tube in front of the saddle, then rest their chest on the handlebars. This not only reduces their frontal area, but it places much of their weight over the front wheel. Therein lays a clue.