Author Topic: Maximum/minimum speeds  (Read 522 times)

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Offline John Nettles

Re: Maximum/minimum speeds
« Reply #15 on: October 15, 2020, 11:43:37 am »
There are a lot more photos going uphill than down.
Totally agree.  Who wants to stop on a great downhill.  About the only place I have done that with any significance is on the western side of Going to the Sun Highway.
Tailwinds, John

Offline Pat Lamb

Re: Maximum/minimum speeds
« Reply #16 on: October 15, 2020, 11:58:33 am »
Well of course there's more pictures going uphill:
 - you have more time to look at scenery going uphill
 - it's work to stop a loaded bike going 20-40 mph downhill
 - no work to stop going uphill, just stop pedaling
 - you need to take a break while climbing anyway, why not get out the camera?

Offline Westinghouse

Re: Maximum/minimum speeds
« Reply #17 on: October 16, 2020, 08:53:51 am »
A couple on a Santana tandem on the northern tier in 1987 told me they hit 59 mph going downhill. I think I got up to around 37-40 mph downhill. In France I did 6 mph down hill against a devil of a wind. In 1994 in Italy I averaged about 17 mph on flat roads carrying 60 pounds of gear.

Offline TCS

Re: Maximum/minimum speeds
« Reply #18 on: October 17, 2020, 12:25:07 am »
Quote
Who wants to stop on a great downhill?

None other than Greg Siple was spotted walking down hill on a long ago TOSRV Texas.  When asked if he was having trouble, he replied, "No, it's just real pretty here and I didn't want to rush past it."   ;)
« Last Edit: October 17, 2020, 02:07:44 pm by TCS »
"My name is Pither.  I am at present on a cycling tour of the North Cornwall area taking in Bude and..."

Offline zzzz

Re: Maximum/minimum speeds
« Reply #19 on: October 18, 2020, 06:36:18 pm »
This is very interesting to me. I’ve ridden my whole life but only started touring in my mid-50’s and I immediately noticed that I could not descend faster then 38-39 w panniers, seemingly no matter how steep the grade. I routinely hit mid 40’s going down the steeper stuff around my home where I’m riding w/o panniers. I always assumed it was the extra aero drag but if other people here are hitting 50 something else is impacting this.
I’m pretty light and I pack pretty light, I’m wondering if a bigger rider who’s carrying more weight develops more momentum that overcomes the additional drag. Anybody on this thread who knows enough about physics to explain this?

Pete

Offline John Nettles

Re: Maximum/minimum speeds
« Reply #20 on: October 18, 2020, 07:12:33 pm »
I don't much about physics but I tour with a heavier guy who carries a $hitload of stuff. He carries 4 panniers, HB bag, & a rack pack for just an overnighter. On some mutliweek trips, he has been known to take that plus a trailer with gear on it.

Anyway, on decent downhills, he can out coast me fairly easily regardless how tight I tuck. 

The time I almost made 50mph, I was young, very strong, skinny, had only 2 rear panniers (about the same as front panniers now so somewhat narrow), with my foam mattress on the rack and a HB.  It was a massive downhill and I had a pretty strong tailwind.

That said, my "usual" top downhill speeds over the past 5 years or so are between 35 to 40mph, rarely over 40 but it does happen about once per week on average.  I am a bit reckless on downhill corners due to my really old racing days and can tuck pretty narrow and low which helps quite a bit. I typically tuck my knees together under the top tube and bend my elbows in as much as possible while keeping a flat back. 

All you need is a steep downhill, smooth road, fast tires (I use Marathon Supreme usually),  a tailwind, and be too stupid to have a fear of corners since it always seems the fastest downhills have lots of curves.

Tailwinds, John
P.S. My fastest ever speed was when I was young and racing.  We would go out occasionally into the countryside and draft behind one of the other racers who had a van.  He rigged it so the rear doors would stay open and mounted a piece of plywood as a cover or top over the rear doors so it created a 3-sided "cave" which created one heck of a "vacuum".  It would suck you right along with little effort (for a young racer) until about 40mph.  We would switch the chainring and freewheel (old Regina) to a 58/13 combo and spin like crazy.  That is one good thing about riding on true rollers is that you get very good at doing a smooth cadence.  Anyway, my top speed then was 54mph which was fairly foolish considering I was probably about 3"-6" from his rear bumper.  Some of the older racers (I was a teen) could top 60mph but they were truly nuts as they looked like a gerbil on a wheel they were spinning so fast.  One thing is you got super hot as there is barely any wind and you are working pretty hard.  However it is fun to just cruise along at 40mph. 

Offline zzzz

Re: Maximum/minimum speeds
« Reply #21 on: October 18, 2020, 07:57:34 pm »
It would certainly seem that we have a shared history. I started racing when I was 15 in 1973 so I am familiar w all the touchstones you listed (freewheels and rollers and doing speed work by drafting behind a van) and I have done some pretty aggressivly reckless (re: stupid) stuff on the bike over the years especially when I was younger. I continued to race until I was 40.

My first tour was when I  was 55 &  I took the WE to Pueblo then across on the Trans Am. When I got to the top of Carson Pass,it was freshly paved and I let the bike go and I really had to push it to hit 40. So something was different because on a unladen bike I would have been bumping up against 50 on that descent w the fresh pavement.

Offline John Nelson

Re: Maximum/minimum speeds
« Reply #22 on: October 19, 2020, 02:12:39 am »
This is very interesting to me. I’ve ridden my whole life but only started touring in my mid-50’s and I immediately noticed that I could not descend faster then 38-39 w panniers, seemingly no matter how steep the grade. I routinely hit mid 40’s going down the steeper stuff around my home where I’m riding w/o panniers. I always assumed it was the extra aero drag but if other people here are hitting 50 something else is impacting this.

To hit speeds above 50 MPH, it takes more than a steep hill. It takes a long, long, steep hill, preferably steep for well over a mile. It takes time to build up speed. And of course to be safe, the pavement needs to be smooth, no cross roads, no strong winds and relatively straight. And I prefer a long, straight flat area at the bottom of the hill to slow down on. Come ride in the Rocky Mountains. We have lots of such roads.

And yes, extra weight helps, so panniers facilitate speed and more than compensate for the extra drag.