[Closed] Nearly cracked 50mph today...

You should easily be able to get 60 on a road bike.

I did 49.9 coming down Bacup rd. was well cheesed off I didn't get 50 but that was on a 4" full suss with knobbly tyres.

Mate, I'm well aware the TDF guys are known to top 70, but I've not got the big hills they're riding on, the gearing, the technique or probably the balls either...

Anyway, I've done 160 on another form of road bike, but that's another matter...

EDIT: Respect to thepodge... Years ago in the Alps, my mate with a computer on his bike reckoned he hit 52mph coming down a steep fireroad (so offroad) on our DH bikes, but I'm not convinced it was calibrated properly. It was certainly over 40mph, possibly over 45, it was quick though... But I'm trusting the GPS on this one anyway...

You should easily be able to get 60 on a road bike.

40 is easy.
50 is a challenge.
60 you need to have a lot of skill and balls and a very big hill - ideally without much in the way of traffic and potholes and with enough of a run out.

I've only ever managed 60+ mph once in this country and it was frankly terrifying. Done it a couple of times in the Alps though.

47 or so happens quite regularly where i cycle but it is hilly around my area.

Did hit 50 once on my Tourer coming down the Crow road on the Campsie Fells with a tailwind and the front end shimmying all over the shop !

Bit buttock clenching.

Much more stable on my current bike at that speed.

Can recommend the road from Dunoon to Loch Striven for high speed thrills. Though the front end coming off the ground over some crests is a bit interesting !

You should easily be able to get 60 on a road bike.

Its not that easy I hit 59mph once on Dartmoor and live on top of the Mendips .Even tried on my tt bike with skinsuit on using 55x11 and only hit 57mph riding off the Mendips with a tail wind

Malverns down to Welland ?
How about British Camp down towards Ledbury, wouldn't that be better* ? 😉

*Possibly displaying lack of local knowledge here. I [i]think[/i] that ones longer and steeper.

Was pleased at setting the 30 mph sign off a month or two back on my mountain bike. Checked the gps in my pack and had done 42. 😳

Malverns down to Welland ?
How about British Camp down towards Ledbury, wouldn't that be better* ?

Don't get the idea your gearing is a limitation - at 50 (or even 40 for ordinary mortals) you're far better off being in a full tuck than sitting up a bit to pedal.

@mboy, it took a lot of studying os maps to work out the steepest bit and how to hit that point at full pelt. did the full on airo-tuck and everything, I never do it now.

I once rode, for a stretch, in Acle, at 42mph. This was on a 1992 or 1993 GT Outpost weighing some 35lbs or so.

You should easily be able to get 60 on a road bike.

🙄

48mph is the fastest I have done but there are no long steep downhills around here and I've only got a compact. 60mph sounds scary on anything but a wide, smooth, straight, and empty road.

Managed 60km/h on a short downhill stretch of road in Weardale today on a 5" FS with very muddy mud tyres on. Was still accelarating when I reached a 90deg. left hand corner and had to knock speed off.

41mph on a mtb with slicks is as fast as I've gone, scarey enough for me!

Managed 62 off fleet moss. Bloody good fun but somewhat scary...

Nope - Malverns down to Welland is significantly steeper - though I've only ever ridden up that, not down, so no idea whether or not it's a 50 hill. Don't even break 40 going down towards Ledbury though IIRC.

Yeah, the roads off the top of the Malverns especially down to Ledbury, in any direction, are all quite long, but nothing like as steep as the start of the road to Welland.

And as for it being a 50 hill, if I can do 48 on it with little effort, someone covered head to toe in skin tight lycra, with a decent aero tuck and a good set of legs to get good acceleration off the sharp left hand bend, should probably be able to push 55+ coming down there, maybe even 60 before the road starts levelling out. But you'd need to REALLY gun it out the corner for sure.

Oh, and I'm sure some eye protection would help too, I backed off a bit mainly cos I couldn't see anything cos my eyes were streaming!

i've got over 50 a couple of times, never got close to 60, and to be honest not sure I'd want to

I have done 45 with a BOB acting like a rudder 😯

Barbary Castle nr Swindon. 63mph.

I never do it now

bloody right!

46 mph at La Molina DH in the Pyrenees. Shaking like a sh***ing dog at the bottom 😳

i got 43 mph on my MTB down cobbly hill, too scared to try it on the road bike because of rim brakes and the hairpin left over a blind crest hump back bridge over the canal at the bottom

And as for it being a 50 hill, if I can do 48 on it with little effort, someone covered head to toe in skin tight lycra, with a decent aero tuck and a good set of legs to get good acceleration off the sharp left hand bend, should probably be able to push 55+ coming down there, maybe even 60 before the road starts levelling out.

You should easily be able to get 60 on a road bike.

Pah! I managed 90mph on my Grifter, coming down a wheelchair ramp.

I wooduv dun wunundred, but I was skinning up at the time.

aracer, do it, let us know how you get on. Though personally, you wouldn't catch me trying it on a TT bike! Maybe put the aero wheels off it on your normal road bike, but the extra speed from the Tri bars really wouldn't be worth the lack of control IMO.

But yes, that road is pretty much ideal as it's got the worlds longest run out pretty much.

Did 45mph on my Raleigh Mustang. It was too big for me and I had to use the Profile aero bars that plugged into the bar ends, 21" version if I remember right, to get to that speed. Also to get to that speed there was a corner we had to cut, we took it in turns to go first and give the all clear. Those were the days.

Bust 50 coming down the road from the quirang in skye. Couldve done faster but I was losing the light. Paced in a car.

48.2 off road on a mtb via gps
there is a pic of the gps unit somewhere on here but i dont have a copy.

51.3 on my cyclocross on the commute home, felt bloody fast, don't think I could get more down the road as it opens up at the bottom of the hill and you can get a nasty cross wind, makes things wobble a bit!!

Fastest road bike descents in Herefordshire .
54mph on Stockley Hill over near Peterchurch and 53mph on the road down from Capler Camp near Fownehope. Twiddle 53x11 up to about 40mph 'ish then tuck in and hang on for the ride.

Did 55mph on the flat once behind a big coach, back in the day, on Formby bypass - but that's another story.

Oh the Tumble dropping down from Blaenavon to Abergavenny is another cracking 50mph descent - you can also bunny hop the cattle grids at 40 plus if you have the bottle!

Bust 50 coming down the road from the quirang in skye. Couldve done faster but I was losing the light. Paced in a car.

That was on MTBs

Hit 53mph coming off the Galibier. My mate passed me. He claims he topped 60mph. Certainly seemed possible giving the rate he pulled away from me. No doubt I could have gone faster but did not have the bottle

I once hit 55 on the road from Lochranza to Sannox, on Arran. This was on on my mountain bike on slicks which was decked out with panniers front and rear, must have weighed about 70lb with all the crap I had taken. This was back in the days of canti brakes and no sense of my own mortality.

50mph is quite common around here in S.Wales .. lots of little descents to get that.
Once did 62mph down Caerphilly mtn ... that was very scary as anybody who knows of the descent will know. Try to keep it low to mid 50mph now though.

50mph is quite common around here in S.Wales .. lots of little descents to get that.

Screw all this willy waving
Post your max speed on your SINGLESPEED and include the gearing

48x17 pompino
42.4mph

Post your max speed on your SINGLESPEED and include the gearing

barrykellett - Member
Screw all this willy waving

Attempted willy wave

[img] [/img]

"easy to do 60" - LOL!

Much more than 50 is properly hard to attain IME.

Managed 52mph coming off the Bealach na Ba towards Applecross last year which is probably fastest I've done in the UK.

It's reasonably easy to get low 50s mph in the Alps, but the 100kph target has eluded me. Closest was a round 60mph (97kph) coming from the Col d'Encrinaz heading towards Pont des Gets - there's a long steep straight after the Praz de Lys junction you can really let it fly on.

Plenty low-mid 50s on other cols; I find it really hard to get much more than that as you need a proper steep, straightish road anyway and even if you get that there's often other traffic and restricted sight lines. Given you probably would die if you came off at these speeds, I tend to err on the side of caution.

I hit 49.9 mph going down Old Wyche Road in Malvern on an mtb, I think it's a bit too lumpy to do it quickly on a road bike...

Have hit around 50 on the bit of road between Abinger and Westcott on the road bike. Didn't feel too bad as the road is smooth like a snooker table. 40 off the top of Ranmore and I was not happy at all; very nervous in fact.

aracer - Member
What does that prove? As I mentioned above, over 40mph you're better off tucking and coasting no matter what your gearing. Max speed on your FIXED maybe...

It proves you lot will argue about anything.

Bloody hell, I'm still on a quest to break 50mph, and I've done most of the big roads in Scotland at least 🙁

13thfloor monk - you need to be fatter and a have a tailwind 🙂 racing snakes simply don't have the weight for good downhill speed

Bloody hell, I'm still on a quest to break 50mph, and I've ridden most of the big roads in Scotland 🙁

So what are the factors here, body weight? Tyre pressure? How can folk hit 55mph on MTBs when I'm tucked with my belly on the nose of the saddle coming down the Kenmore road and still just managing 47mph?

Swear I would have broken 50 on the Lechtd road if the crosswind hadn't been trying to lift my front wheel off the road...

edit: weird double post there.

Compacts are for women only arent they?

I think body weight makes a huge difference. You only get a small increase in frontal area thus drag but a large increase in the force pulling you down the hill for the extra lard some of us carry. The tandem is noticeably quicker for this reason

A good tuck helps as well- head low but arse in the air gives good results.

A tailwind makes a huge differnce - even a few mph as at speed almost all the drag is aero

51mph down the Graine Road from Bury to Blackburn.

First ride out on my new (to me) road bike, with 16 year old alloy forks 😀

Used to love doing this as a kid, but the above just scared me.

Bacup Rd on the MTB sounds interesting.
I take it that the straight drop to Bacup is faster than the curvy descent to Tod?

48.8 is the highest my speedo's ever read, somewhere on the Dartmoor Classic- no doubt if you knew the road you could easily get >50 but I didn't arrive at the right speed to do it.

On that particular bit of road it wasn't scary but I don't think there are many places in the UK I'd want to go much over that, and I'd probably be terrified at 60 even if I could get up to it.

I think body weight makes a huge difference. You only get a small increase in frontal area thus drag but a large increase in the force pulling you down the hill for the extra lard some of us carry. The tandem is noticeably quicker for this reason

That sport of speed must be absolutely terrifying for the stoker!

Hmm, about to prove myself completely ignorant of the laws of force and acceleration here, but I thought your acceleration due to gravity remained the same regardless of your weight (i.e. 9.8m/s2) and that heavier folk would merely accelerate slower down the hill to the same top speed? Didn't Galileo prove this with an orange and a cannonball?

Anyway, apologies, I've dragged a good thread into physics and engineering...

edit: dammit, contradicted myself, you can't 'accelerate slower'... Now I'm really confused.

I once hit 55 on the road from Lochranza to Sannox, on Arran.

Thats my fastest ever location too. Don't think I managed 55mph though, was catching my mate fairly quickly who claimed at top speed of 45mph so call it 48mph.

Above 30mph on a bike feels fast, above 40 feels bonkers. Maintaining 50mph + on Alpine descents must take balls of steel

13th - yes the acceleration due to gravity in a vacuum is constant and the same regardless of the weight of the object.

Its when you add in wind resistance that it changes. We are also talking abot terminal velocity not acceleration.

A fat bastard has a much larger force pushing him down the hill - but only a bit larger wind resistance so the acceleration is the same until wind resistance becomes a factor and the terminal velocity will be higher.

think parachute v lump of lead

Hmm, about to prove myself completely ignorant of the laws of force and acceleration here, but I thought your acceleration due to gravity remained the same regardless of your weight (i.e. 9.8m/s2) and that heavier folk would merely accelerate slower down the hill to the same top speed? Didn't Galileo prove this with an orange and a cannonball?

While this law is true, it only holds in a vacuum or if we ignore the effects of air resistance. Think of a big feather weighing 10grams and a ball bearing weighing the same, which will fall faster?

Galileo used different sized cannonballs I think, so whether he intended to or not, he was cancelling out the effect of air resistance by using objects with different mass but the same density and shape

I hit 49.9 mph going down Old Wyche Road in Malvern on an mtb, I think it's a bit too lumpy to do it quickly on a road bike...

I've hit 51.8 on rollers does that count? 😀

Hit 51mph going down Butser hill offroad (between Portsmouth and Peterfield literally E of the A3) a couple of years ago. I had the advantage of being about 17st kitted up plus a tailwind. not scary at all for some reason!
My previous max was 49.5mph on my old Marin coming down the Radar station rd from the top of the Pennines to Knock (E of Penrith) that was scary,

Right, right, I've figured it out. 😀

I'm ignoring stuff about wind resistance, assuming thats the same for everyone.

The cannonball analogy doesn't work here because that is objects in freefall, and the force applied to them is the force DUE to the acceleration of gravity (i.e. they both accelerate at 9.8, however the heavier object experiences a greater force to achieve this).

The difference with bikes is the reaction force from the road. your acceleration due to gravity pushes you into the road. The heavier you are, the more you push into the road. The road pushes back at an angle perpendicular to the road surface. On any road that slopes downhill, a proportion of this 'push back' will in fact be 'push along' and THAT is the acceleration you feel on the downhills.

Difficult to explain without diagrams, high school physics though... 😳

13th - try wiki on [url= http://en.wikipedia.org/wiki/Terminal_velocity ]terminal velocity[/url] teh only difference for us is that on a slope you only get a % of the downward force but everything else remains the same as a freefalling object in air

I'm ignoring stuff about wind resistance

once went down a hill (with howling tailwind) on the drops, 52x13 on 700c wheels, REALLY going for it, max was 49.9mph.
properly gutted that i hadnt broken 50.
fast forward a decade (to the late 90s)
went over the top of a hill on the A689 alston to bishop auckland road, on an aging mtb with tioga psycho tyres, panniers, (with 2 dozen eggs in em!)
no front brake and the rear mech screwed into the middle of the block due to a snapped cable.
i knew i was really shifting, big tailwind too, eyes streaming because of the wind, got further down and as the road levelled i glanced down to find i was still doing 55.
max recorded was 62mph.
i am still slightly gutted that i didnt do 100kph, but tbh, i doubt i will go that fast on a bike again.

If so you're missing the whole point

No I'm not, on my particular little tangent I'm trying to figure out why, for two otherwise identical riders, the heavier would be faster on a downhill, which is why I'm ignoring wind resistance.

Basically, its correct to say that the heavier rider has a bigger advantage due to gravity, but its not actually gravity thats pulling him down the hill, its the road 'pushing' him down the hill 8)

Edit: I'm descending into needless pedantry here, step away from the thread!

"Can recommend the road from Dunoon to Loch Striven for high speed thrills. Though the front end coming off the ground over some crests is a bit interesting !"

StuCol - Agreed, I was brought up living on that road. There are some pretty quick bits!

13th - nope 'tis the wind resistance that makes the difference in the terminal velocity - read the wiki link

The difference with bikes is the reaction force from the road. your acceleration due to gravity pushes you into the road. The heavier you are, the more you push into the road. The road pushes back at an angle perpendicular to the road surface. On any road that slopes downhill, a proportion of this 'push back' will in fact be 'push along' and THAT is the acceleration you feel on the downhills.

Nope. Sorry wrong I'm afraid, if you ignore wind resistance then 18stone rider will accelerate at the same rate as a 9stone rider, the physics works the same as in freefall

Having ridden the same road a number of times and getting various different top speeds (50-61mph) I think the things that make the difference is wind direction and how much speed you create on the bike before you run out of ability to pedal. eg on the same hill when my legs are knackered I've never got a high speed, but with fresh legs you can spin out quicker ie more towards the top of the hill so you have already given gravity a big helping hand.

Definately having a big gear helps. I've only ever got over 60 on a 53 - 12

Yep, but I'm not arguing terminal velocities, as they would be equal for two riders who were identical in every respect bar weight. Hence the cannonball/orange experiment.

I did 54.9mph down this (51°39'37.84"N 3°26'23.53"W) got speed wobble and sh*t my pants somewhat, speed camera wend off at the bottom with me doing about 48mph.

I'll be take it easy from then on, coming off at that speed just doesn't bear thinking about.

*waves white flag* I've argued myself into a circle... 😕

I see where you're coming from TJ, top speeds ~ terminal velocities, as you're at the point where you can't usefully propel yourself any further.

Still not convinced about the effect of rider weight...

"I'll be take it easy from then on, coming off at that speed just doesn't bear thinking about."

Why? Its more likely to mean less broken bones than if you fall of at 10mph. Of course there would be no skin left on your body...

Have hit around 50 on the bit of road between Abinger and Westcott on the road bike. Didn't feel too bad as the road is smooth like a snooker table. 40 off the top of Ranmore and I was not happy at all; very nervous in fact.

You mean Hollow Lane? From Abinger Common down to the A25 near the Wootton Hatch? I pinch flatted coming down there in the pouring rain on the road, by the houses at the bottom. A pinch flat at 40 is a lot scarier than not pinch flatting at 60!

I've regularly done 50-something coming down from Coldharbour to Dorking. Was noticeably quicker with some 50mm deeps. That they had a penchant for rolling fully inflated tyres was something I tried to forget!

IMO it's the gradient as much as the length that's key for good top speed. Did c53 in a 40 (setting off a speed camera) on the A283 on a fairly innocuous looking hill. PB was in Lanzarote, perfect road really, absolutely dead straight, wide, perfect surface and a good gradient. Forget the exact figure, 60+. Felt less scary than some of our roads at 50 though! That was in a very tight pace line with some nutter triathletes. Annoyingly we got to the bottom, round the roundabout and came back up again, 2 miles of utter torture!

Not really sure about folk thinking it's harder/more scary on an MTB though. When your hands are right by the stem, and your nose is on the bars it's fairly irrelvant what shape your frame is!

41mph down Mastiles Lane descent earlier this year. Yes, that's off road for those that don't know.

Okay 13thfloormonk I'll try and explain.

We will use freefall as an example.

So you have an 80kg sky diver gravity acts on him with a force of 800N (with some rounding) He jumps out of the plane and initially and accelerates at 800 / 80 = 10ms2 (accelaration being equal to force divided by mass). However as his speed builds so does air resistance. It builds until the point where it equals the force of gravity on him, so he stops accelerating, he has reached terminal velocity.

No imagine we stick 20kg of lead on his back and he is falling in the same position, Gravity is now exerting a force of 1000N on him therefore the air resistance requred to stop him accelerating is also 1000N, in order for the air resistance to equal 1000N he needs to be falling a bit faster so his terminal velocity will be higher.

Same basic principle holds true for blokes on bikes freewheeling down a hill

[url= http://www.sportsci.org/jour/9804/dps.html ]Cycling specific explanation of the physics behind climbing and descending[/url]

Man, road bikes are exciting.

Eh... really? Gravity is not a force, its an acceleration. Acceleration due to gravity is 9.81 m/s2.

In your example the 80kg sky diver will experience a force (due to the accleration of gravity) equal to 80*9.81=785N. The 100kg skydiver will experience a force of 981N. The net result however is that the two skydivers will both accelerate at 9.81 m/s2.

What you are suggesting (heavier falls faster) is in direct disagreement with established principles (or at least, what I have assumed are established principles from memory).

13th - add in the effects of wind resistance than given the same frontal area a heavier object will reach a higher terminal velocity

TJ, I agree, when descending on a road. However, this would not happen in freefall, as has been proven repeatedly (experiments on the moon with a hammer and a feather, air resistance non-existent, both objects land at the same time).

I wasn't actually disagreeing with the fact that heavier riders could achieve higher speeds on descents, I was just trying to establish how, and, for fear of turning this into a thread that never ends, still believe that my intial argument is correct.

Try the cycling specific paper above ^^^