85kph (50+mph) possible?

fauxpas said:

Is 85kph (50+mph) possible down a steep hill?

My cycle poota had been functioning fine and when I zipp down a steep hill every morning, I don't even try and go fast and roll down doing 60kph. This morning, I made a concerted effort to obtain a fast cadence down there and I must admit, I've never pumped so quick in top gear in my life.

I get onto the flat and look at the poota and it says max speed 87kph, which is about 54mph I think.

Did my cycle poota misfunction? Or is that speed possible?

I'm not wanting to brag, as I know it is a steep hill, I just wanna know if my cycle poota needs binning. 😕

Whether your computer's measurement was accurate or not depends on whether you properly calibrated/setup the computer, or if you did it at all. It's not hard, at all, to hit speeds of 50 or even 60+ mph on steep or extended downhills.

I'm sure I put in the correct measurement when setting it up, and when reading 20-30kph riding normally, it surely feels right.

I will be checking its accuracy on the weekend when I compare it to my gps sat nav. I just thought at high speed, the poota had a heart attack.

That's why I didn't get a wireless unit, I didn't want any interference.

fauxpas said:

I'm sure I put in the correct measurement when setting it up, and when reading 20-30kph riding normally, it surely feels right.

I will be checking its accuracy on the weekend when I compare it to my gps sat nav. I just thought at high speed, the poota had a heart attack.

That's why I didn't get a wireless unit, I didn't want any interference.

The numbers given in computer manuals for tire circumference are often off, by quite a bit. It's better to measure the tire by doing a roll-out measurement.

Yes, it is possible.

The manual shows a diagram with the diametre x pi...

But when setting the parametres up in the poota, it asks for diametre in cms...

What computer do you have?

fauxpas said:

The manual shows a diagram with the diametre x pi...

But when setting the parametres up in the poota, it asks for diametre in cms...

An overly accurate method:

Pump tyres to normal riding pressure - paint a thin strip of paint on your tyre - get on bike and roll two or three wheel revolutions - measure distance of "paint to paint" marks on ground/wifes persian carpet - take average - input average into computer in cms.

Done.

85km/h is easily possible. Done it on my road bike and mtb with slicks.

Its a Topeak. Inexpensive job off ebay via hong kong...

This afternoon, I was doing 60kph in a 60kph zone and I was doing the same speed as the cars, till the road flatenned out and I could not maintain 60...

Eldron said:

An overly accurate method:

Pump tyres to normal riding pressure - paint a thin strip of paint on your tyre - get on bike and roll two or three wheel revolutions - measure distance of "paint to paint" marks on ground/wifes persian carpet - take average - input average into computer in cms.

Done.

85km/h is easily possible. Done it on my road bike and mtb with slicks.

damn [censored] 85km/h would be pretty scary on a MTB. mine feels a little crazy even in the high 30's (i think my max speed has been 38- i've never put slicks son)

Its a simple matter of physics energy vs resistence. Down a steep hill there is plenty of potential energy being converted to kinetic energy, add to that the energy coming from your legs and presto, your going too fast for your own good.

What gearing have you got on your bike?

Dude - get your chin close to the stem down Mt. Victoria pass in the Blue Mountains, you'll hit 90k no problem. Although I often wonder: " what are the odds of my tyre giving way ??" or "do spokes break going DOWNHIL??"

~gm~

Its definately possible. Although I did it back when i lived in europe and it was a road bike. Its still quite possible with a mtb. I hit 55mph and my front rim wobbled a little bit and it scared the heck out of me. Congrats and be safe.

fauxpas said:

Is 85kph (50+mph) possible down a steep hill?

My cycle poota had been functioning fine and when I zipp down a steep hill every morning, I don't even try and go fast and roll down doing 60kph. This morning, I made a concerted effort to obtain a fast cadence down there and I must admit, I've never pumped so quick in top gear in my life.

I get onto the flat and look at the poota and it says max speed 87kph, which is about 54mph I think.

Did my cycle poota misfunction? Or is that speed possible?

I'm not wanting to brag, as I know it is a steep hill, I just wanna know if my cycle poota needs binning. 😕

I hit 50mph the other day on the flat with a 35mph+ tailwind. So yes 50mph is possible on a downhill.

No problemo. You can hit 85 senza problemi in the right conditions. Hammer on your 53x12 on a long downhill, maybe with a wee bit of wind behind you.

It is wonderful. Then you spin out, get down as low as you can, if you know what you are doing you stick your nose on your stem, belly on your seat, butt in the air, holding a super-tight position with your legs, with your arms tight against your sides.

Then you begin to pass cars without even pedaling... and maybe [censored] a look at the guy in the sardine can starting at you in disbelief. Life is good. 😄

When I was a bit younger and a bit more sure of my immortality, we used to chase and sprint after public buses (on routes where we knew the stops... 😉) and we would easily be able to maintain something in the range of 60~65 kp/h on the flats for a few kms...

Great for your confidence, and the people standing in the back of the bus watching (and often) cheering you on.

Powerful Pete said:

No problemo. You can hit 85 senza problemi in the right conditions. Hammer on your 53x12 on a long downhill, maybe with a wee bit of wind behind you.

It is wonderful. Then you spin out, get down as low as you can, if you know what you are doing you stick your nose on your stem, belly on your seat, butt in the air, holding a super-tight position with your legs, with your arms tight against your sides.

Then you begin to pass cars without even pedaling... and maybe [censored] a look at the guy in the sardine can starting at you in disbelief. Life is good. 😄

When I was a bit younger and a bit more sure of my immortality, we used to chase and sprint after public buses (on routes where we knew the stops... 😉) and we would easily be able to maintain something in the range of 60~65 kp/h on the flats for a few kms...

Great for your confidence, and the people standing in the back of the bus watching (and often) cheering you on.

I can't go that fast.... My ears are way to big. I would be concerned that they would cause some bad harmonic vibrations and I would do a Bobby Julich in the corner.

The Squirrels in my neighborhood are suicidal. When they can't find a car then they go after bicycles.

😄

lw

lwedge said:

The Squirrels in my neighborhood are suicidal. When they can't find a car then they go after bicycles.w

Mental note: another great reason for riding here in Rome... no squirrels. Do you have big ugly orange public buses in California? 😄

Powerful Pete said:

Mental note: another great reason for riding here in Rome...

You guys may not have squirels, but you do have lots of Smart cars... Slightly larger than a squirrel with a better legal team...

SaintAndrew said:

damn [censored] 85km/h would be pretty scary on a MTB. mine feels a little crazy even in the high 30's (i think my max speed has been 38- i've never put slicks son)

It's the only way to live!

Descending a long winding downhill on an mtb with slicks beats a road bike anyday (for fun not speed). It may not be faster but there is so much rubber that you can lean crazy far over knees (almost) down ala motorbike style.

My recommendation is 26x1.75 slick. The one inchers are just too narrow...

Powerful Pete said:

No problemo. You can hit 85 senza problemi in the right conditions. Hammer on your 53x12 on a long downhill, maybe with a wee bit of wind behind you.

And a De Rosa ! 😉

-Mike