BIKEPGH MESSAGE BOARD ARCHIVE

Greenfield Avenue is a nice hill. But I lay on the brakes on any hills around here. You just can't trust the road conditions...if there's a new pothole it may be impossible to see even on a straight downhill. And this time of year black ice is rampant.

I hit 40 heading down Fifth to the Birmingham Bridge, on a fairly regular basis.

A few years ago, they repaved 18th. I could cruise a good speed on that. Last time I went down 18th, the pavemetn was not so good and I used my brakes.

Geyer Rd in Millvale between Mt Troy Rd and Babcock Blvd

No speedometer, but I get up to "holy !@#% this is sketchy" speed whenever I go down Greenfield Ave. I quickly pull away from whatever car happens to be following me. The pavement used to be pretty decent, and I memorized where the little holes and such were.

It has a bunch of giant potholes now though, so I'd skip going down at any rate of speed, probably even after they do their lame patch job.

I often felt that of anywhere I ride, I have often felt that coming down Greenfield, with cars pulling off or onto Swineburn was the spot I would have to choose either evasive manuevers or laying it on the pavement. Especially with the morning sun behind me in the spring time.

I even feel sketchy going fast down hills in the middle of nowhere. I've hit wildlife in my car doing such things...no reason it would be any different on the bike.

Negley Run Boulevard, going downhill from East Liberty to Washington Boulevard (by the bike track) is where I've maxed out my speeds, usually in the high 30s. It's pretty straight, and most of the time I've gone, car traffic was pretty light.

Seems like Browns Hill toward Homestead might be a good run.

Arlington/josephine was always fun for me, flying down at 3am on my way to work, when no cars, no buses, and the occasional other cyclist were out. I always had tons of fun until I reached this series of curves. I've worn out many a shoe due to bad brakes and this series of curves

Looking at streetview, it doesn't seem so bad, but I remember being terrified at times, haha.

I've gotten in the mid 30's on Browns Hill/Grays bridge. The pavement is iffy (and I'm a sissy).

county line road coming down from seven springs is probably the longest, straightest, downhill i've been on.

but for something closer, the one thing that springs to mind is kittaning pike coming all the way down from dorseyville road.

I just posted over on the other thread that using Burgess-Hazleton-Suffolk as an alternative to East or Federal or Perrysville would give you what you need. Not Burgess or Hazleton themselves, but Suffolk, going east, gives you that 100 yards of slight uphill before the stop sign at East.

Right next to me in McCandless, Perrymont going east off of Perry is routinely plummeted down by two-ton tin cans on the high side of 40 mph. Then of course is that stiff left bend at the bottom, but you have a bit of time to slow down. (Side note: A county highway crew was replacing the guardrail along here just this morning.)

For that matter, Perrymont westbound from Fox Ridge down to the gas line is a nice little drop, too. I don't have a speedometer, but I routinely take the lane here and feel I must be going 35+ since I can keep up with a car ahead.

Happy trails!

Heading down Coxcomb Hill towards Logan's Ferry is the fastest descent I know of in the area. Steve is right about County Line Rd as well.

Another good one would be Perry Hwy going north just past the Ross bus garage. There is a traffic light toward the bottom, for the HOV Lane and Park & Ride, but it's usually green at non-rush. If you don't plan to turn onto Center, it's a good quarter mile downhill with no need to stop.

Rochester, either way off of Perry, is also a good bet. Perry is a ridge road, so many of the roads going off of it are downhill.

I wouldn't recommend Old Perry, coming south out of Wexford, because of a lot of driveways and subdivision street access, not to mention bad sight lines and a hairpin turn at the bottom. But if you dare, mainline US19 Perry Hwy going south out of Wexford, you'd damn well better be going on the high side of 40 or you'll get killed by the cars going 60.

2nd Steve k. I've hit 45 on Kittanning Pike... not too many side streets to watch for, just driveways. Also: watch your line with the spaced out asphalt manhole covers below the fire station. I had to bunnyhop one last year and nearly ate it.

Personal max speed was set on Coxcomb Hill Rd, a long, steep, gently curving road with no intersections descending into New Kensington. I had to hit the brakes because a car was going too slow in front of me.

One good study on bike accidents showed risk factors to be 1) Speed over 15 mph and 2) Age over 39.

That pretty much makes me a goner either way.

Oh yeah, I'm pretty sure if you bomb county line road you could hit 60+ mph. Last time down it I did low 50's while sitting high on the hoods and feathering the brakes.

Sounds like you have some North Hills riding experience, Hidden Variable. My top speeds have been recorded on Mt Royal Blvd as it goes down from Shaler to Etna. Often in the low 40's - 44.3 mph max.

Also, Forward Avenue can be fast on the top end, but you need to slow down for the windy curves at the bottom.

I hit 50 on a bike exactly once to know it, when I was about 12. My sister's 24" 3-speed had a speedometer. The hill was Behm Road (misspelled Behn on this map). Note the railroad track 3/4 down, and the T intersection with NY240 at the bottom. That's a 300-foot vertical change in a half mile. In the current Street View pic, the tracks are gone (they were very active in 1971), but that's not your imagination, the road simply drops away past the tracks.

This is a great thread... I'm not sure I've ever hit 50 so I have to count it as no. I remember trying on this stretch of 136 in Madison where i grew up, but I don't remember if I made it or not. I was on a MTB so it would have been quite a feat.

Seems like there's a lot of opportunity to do 40, but 50 is tough...

Liberty towards the strip might be a possibility. I know I've done 40+ down there - including on a nighttime flock/mass ride, which was really dumb, especially considering the construction holes/plates that I didn't know about. I think the main problem there is Herron, you definitely have to slow down well in advance.

Greenfield, and Forward.

I wouldn't trust anything over 30 mph on Liberty inbound, and that's riding in the relative shelter of traffic. Too many side streets for one thing. Two, at 5%, not that steep of a descent to really let it hang out for a half mile & pick up speed. Around here you need something pretty steep & fairly straight to push over 40. Liberty is not the ground for it.

That being said, if anyone can come up with some proof of hitting 40 on your bike on Liberty it's your choice of a case of beer on me.

county line is insane. you can hit 70 easy if you have the intestinal fortitude. just stay a bit to the right as there are a few blind hills where you might very well find some idiot driving in the middle of the road just as you crest.

near to the city my top speed was 57 coming down kirkpatrick st to etna when my cassette shit the bed on me and i had to abandon the first (i think, 2007?) populaire. not having any large rings in the back climbing from fox chapel made me grumpy. the descent helped.

If you are feeling spicy, Hunter/Plum Road is a good one. But, there are some swoopy corners that require some intestinal fortitude and handling skillz.

+1 for Coxcomb Hill.

It's a bit far afield, but descending into Cumberland (say, via 36 out of Frostburg) has a few stretches where you can hit mid-40s with ease, and 50+ with a bit of daring.

Also, Chestnut Ridge near Ohiopyle has a couple of cliffs you can plummet over pretty well. Watch for idiot vacationers on those roads, though.

I haven't come down that way, but I suspect descending Mt Davis towards Confluence would let ya build up a bit of speed as well.

I get just above 30 coming down the hill through the zoo - and then I freak out, and my mind flashes forward to me in the emergency room, hooked up to five different machines - including the expensive one that goes "BING!" Maybe turning 40 has activated that part of my brain that is averse to making a bloody mess of myself.

(Note-please do not read this as a condemnation of anyone else that goes really fast downhill!)

I think I need to get a bike with skinny tires. I max out the gears my Mt. bike going down Forbes through Frick Park. I'm in my highest gear, pedaling like crazy and probably still not breaking 35mph because cars are still passing me.

The fastest I have ever gone with a speedometer is 42 going down a hill on Triple Creek Road near Seven Springs. That was "holy $#!*" fast for me. I think I would drop a load in my shorts if I hit 60 on a bike.

McArdle Rd is nice to ride down since it was repaved 2 years ago. But I don’t consider it safe. I was once passed by a meathead on a very loud Harley while I was going about 40.

Last summer I was riding up McArdle and saw a girl fly past me going down the hill. She only had one hand on the handlebars and her left arm was tucked behind her back like a speed skater. I made a note of it and figured I would try it the next time down the hill. I got to about 35 and started to hear the voice of Kennywood saying “keep both hands on the bar in front of you”. It’s not something I recommend without a lot of practice, but if you are looking to pick up some speed going down hill it works.

I remember going down 40th from Penn to Butler once with an SUV on my tail. I'd taken the lane, and he was not happy about it. At the bottom of the hill (of course I got the light red), he pulls alongside to tell me "Did you know you were going 42 down that hill?"

@quizbot - I didn't have a GPS at the time but I'm fairly certain I've done 40+ on Liberty. I'll get a track next time, but probably not until the weather is nicer.

The one time in cycling where having a little extra weight is to your benefit is going downhill - so I try to take full advantage of it.

PS: speaking of my shiny new GPS, I was playing around with some of the data fields and saw an intriguing one called "vertical speed"...

I hit 7k ft/hr going down Beechwood this morning (~25mph forward speed). So, now of course I have to find a place to hit 10k (probably not hard)... and so on.

The one time in cycling where having a little extra weight is to your benefit is going downhill - so I try to take full advantage of it.

hear hear!

i'm also pretty sure i can get 40 going down liberty, but it depends a lot on the weather. sometimes through there, the wind is such that i can't coast past 20.

Give this a whack:

Hey, get that low and you might be able to get a draft off me...

well, that's a good point - maybe i should get a bent, then 50 is probably no problem? are the smaller wheels any more squirrelly at high speeds?

http://gearinches.com/images/misc/aero-tuck-md.jpg

Also, these guys know what they're doing:

http://www.youtube.com/watch?v=0tFpNsZXWgc

Nice

@salty & hv: I checked my stats from last year & fastest was 36 on Liberty (part of my every day commuting route). Smallest cog I have in back is a 12, maybe I could hit 40 with an 11.

@salty:maybe i should get a bent, then 50 is probably no problem? are the smaller wheels any more squirrelly at high speeds?

Depends on the bent. So much variety in 'bent designs that it's hard to generalize productively.

On mine (700c rear wheel, 406 front, short wheel base), the handling gets a little touchy above 45 or so, but not so much that I've [edited to add:seriously] feared losing it. I've hit 50-52 in the past; would hesitate to go near that speed again without damn fine sightlines.

I've read reports of the highracer 'bents (dual 650c or 700c) being rock-solid in the mid-40s and above, but have not yet had one at that speed.

Mine goes to 11.

Nigel Tufnel: “What we do is, if we need that extra push over the cliff, you know what we do…

Put it up to eleven”

quizbot - what would count as proof? I could use a case of Chimay, or even Sam Smith's Oatmeal Stout. Yum yum.

and i'm down to only 8 bottles of st. bernardus abt 12. then again, i don't think i could ethically ask for a $100+ case.

I'll race you for it.

freeport rd into freeport is a pretty awesome one... there is a 10 mile downhill on st rd 1018 - st rd 1032... not steep enough for anything spectacular but it is a blast.

Pedaling isn't what gets you up to speed. Air resistance is cubic which means it goes up *really* fast. For instance to do ~30mph sustained you put out ~450 watts. To do the sprint at 36-40 mph you put out ~1500w.

Getting low and tucking in is the way to go. Also not all that safe depending on where you are.

Here, everyone watch this, live vicariously, and feel the need to do 40+ mph downhill melt away.

http://www.youtube.com/watch?v=agfpctJEa_4

Besides, think about your brakes. The physics point to a stopping distance somewhere north of 200 feet.

I guess a highway or other uninterrupted road is an exception but I'm thinking of streets like Greenfield and Browns Hill that have side streets...

I think my personal top speed was on Brad's rollers at Black and Goldsprints at OTB--high 50's/low 60's. Though, I don't know how accurate those readings are.

@mpm http://www.eecycleworks.com/VNJune%20BrakeTest.pdf

@mpm: amazing video - yikes!

@chris: interesting prices on those brakes (!!!)

Proof... GPS track would be preferable. It's pretty easy to fudge anything else. And let's be reasonable on the case

Now motivated to win my own bet!

@mpm -Why use wheels?

http://www.youtube.com/watch?v=nuDWx2U1wM8&feature=related

GPS track would be preferable

I remember @rsprake had X00 mph speeds from an iphone gps app. I'd accept punkbuster screenshots or camera footage.

@mayhew: pedalling gets you up to 30 on the (relatively) flat bit of Liberty before the hill gets steep enough to tuck in. I can't put out 1500W but the 275W I can do, makes the difference between (roughly) 36 mph coasting downhill and 40 mph pedalling down it.

Please don't try this on the slag heaps.

http://www.youtube.com/watch?v=P4_xlFtcPLk

This down hill race was old school...

http://3speedtouringinjapan.blogspot.com/2009/04/blog-post.html

Ow! What we learn from this is that you don't use carbon fiber on a downhill record bike. Dumbass.

I liked his outfit though. It's like, Megalycra.

I could see trying that.

@Edmunds I liked his outfit though. It's like, Megalycra.

I could see trying that.

I'm sure you would look magnificent in it.

It's really simple to change tire diameter in speedometer settings & make it look like you're going faster... that's the only reason I pause there. No tomfoolery like drafting behind your buddy's van either... I guess I trust everyone tho

Video would be good but a bit hazardous to get depending on your setup. Don't do anything reckless.

I run out of gear around 33 or so... 50x12. It's probably not too hard to pick up the extra few mph under the right conditions.... I may have set the bar a bit low.

I'm sure I'd get invited to the Macy's parade.

A good spot for some speed is coming down from the zoo to the HP pool. There's a bit of a curve so it is certainly not the best judgement to take it blind at full speed, but if you do, the pavement is usually good and there's usually no traffic. But it's not long enough to get up to top speed by coasting alone.

My top gear is 50x12 as well, 700x32. according to sheldon's calculator that's 33mph @100rpm, 40mph @120rpm (700x23 is ~1mph less). I certainly can't maintain 120 all day but I can do it for a little while.

I'm not obsessive about my speedometer to the point of measuring actual wheel rotations - I use the book value (2155mm). When I've had the chance to cross-reference against something (map, gps, etc) it's seemed pretty close but obviously even 5% is the difference between 42 and 39.8

Well, talking about it is getting old - if the weather was nicer I'd just go out there and do it. I wonder if the extra drag of winter clothing might make it tougher too.

and - once I accomplish the feat, a beer at Gooski's will certainly be enough for me. Maybe 2 beers since we'll have to ride up that damn hill.

yeah, i don't have gps, so i couldn't offer that as proof. i'm pretty sure my speedometer is spot on. and i believe my biggest gear is 52x11 or 52x12.

unfortunately, after yesterday and the last few weeks, my bike needs a bath before i even consider doing that much shifting.

One of my favorite hills for going fast is the Lower Panther Hollow trail in Schenley Park, from Bartlet downward. The actual speed is not that high, but the perceived speed is tremendous. The dirt, gravel and rocks make 25 feel like 45.

On pavement, I've gone pretty fast on a tandem on some of the hills mentioned. But the stoker controls the drag brake, and (wisely) uses it.

wow, I was shocked when I looked at my speedo on the flat part at the bottom of beechwood and saw 26mph steady. I'm usually doing something more like 15 at that point. i saw my max was 33 - on a MTB with 50psi knobbies and 48x13 top gear.

it's amazing what 30kt of tailwind will do for you too bad it's the wrong direction for liberty.

@Chris: OK, 200 feet stopping distance from 40 mph going downhill might be an exaggeration. But the numbers in the study show around 25 feet stopping distance from 25 mph on a dry, flat surface with $400 brakes and comparable tires, with a 150 pound rider in good shape. Of these, the difference between flat and downhill is probably the biggest change.

The numbers in that brake test article are highly suspect. Stopping distance on a standard bicycle on dry level pavement with even half-decent brakes is limited by the deceleration rate at which the rider will flip over the handlebars. So the fact the number were so widely different for different brakes tells me it had more to do with the rider's skill than the brakes themselves. Also, some of their numbers show nearly 1g deceleration rate, which I'm pretty sure is bogus. Usually the handlebar-flip-point is something like 2/3g.

Do you have a reference for any of those claims?

Since the issue comes up indirectly, it's a really good idea for everyone to practice hard, maximum effort stops once in a while, in a safe place away from traffic, so in an emergency situation your mind/body is ready. Even people who have no intention of bombing downhills.

This is the first reference I've read and seems to indicate .6-.8G is possible.

http://books.google.com/books?id=zbfch607wGwC&pg=PA63&lpg=PA63&dq=maximum+deceleration+rate+of+bicycles&source=bl&ots=A2oPklqDus&sig=PI9a6koXpOPvCudZBYatn5lUR1I&hl=en&ei=isBJTfOlJoKs8Aar2vX2Dg&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDMQ6AEwAg#v=onepage&q=maximum%20deceleration%20rate%20of%20bicycles&f=false

Good grief. Jobst Brant agrees as well that ~2/3g is the limit. Don't I have like two jobs to do?

Then it is the word of god. That's probably where I remember the figure from. It feels about right from my own personal experience.

Unless you're riding a 'bent, in which case you flip over backwards going up Canton.

Confucius say, man who flip going up Canton can ride down without faceplant.

I only managed to hit 27.6 into a bit of a headwind on Liberty this am. It's a rare day that there's a tailwind in that corridor.

@quizbot It's a rare day that there's a tailwind in that corridor.

It's rare to get a tailwind on any down hill - the hill blocks the wind in that direction.

What about on a gentle slope?

Top 3 for me (different roads)

44.1 on Fox Chapel Rd

41.5 on Greenfield Ave.

39.2 on Stanton Ave.

oh yeah, also currently enjoying my second westmalle Tripel. . .but out of a St. Bernardus glass Next up: Corsendonk Christmas! (They were out of Rochefort 10, and I almost bought a case of Koningshoeven Quadrupel, but decided to go Tripel instead)

I hope Stanton headed into Larryville gets new tarmac this year. Much needed. Thinking Powers Run Rd you could also pick up a quick bit of steam...

Well, I downloaded my GPS data tonight - on that ride down Beechwood on Tuesday (described above), my bike computer max speed read 32.6 but the GPS max is 29.1.

BUT, on the flat part of Beechwood where I watched my speedo reading 26.x steady over a long period, the GPS data is also steady between 26-27mph for exactly 20 seconds.

http://connect.garmin.com/activity/66606816

So, what's the lesson? I'm suspicious of the GPS being able to accurately capture a "peak" as well as the bike computer due to time elapsing between positions, combined in this case with going around a curve which might "shortcut" the distance. But, I guess I'll have my work cut out for me on Liberty, though being straight should help, and I think whatever speed I reach, I can maintain for a few seconds at least.

Salty, you said you just use the book value for your wheel circumference for the odometer, try rolling your wheel and measure the actual circumference of your wheel. I used to always use the book value until I measured the actual once, it was surprisingly far off, like 5% off.

Sit on the bike while rolling out your circumference. Also: if you want second- by-second recording on the garmin, disable "smart recording" on the device. Better accuracy but it eats up storage space. Backup / download your old rides before enabling.

MB4: measured 80.75" (2051mm) vs 2070 (1%) - 26x2.1"

CC: measured 82.75" (2102mm) vs 2155 (2.5%) - 700x32

there are a lot of variables, so I'm prepared to call that "close enough". i tried to sit on the seat "normally" for tire compression, put a dab of white grease on the tire, and measured the distance over 2 revolutions (all i had room for). i didn't pump up the CC tires and haven't ridden it in 2 months so they're probably low.

also, like i said, the section between 5:00 and 5:20 on that connect link agrees almost perfectly with what i saw on the bike computer.

when i get a chance to watch the speed display on both, the GPS seems to be a lot more "jumpy" in general. based on what i know about GPS, i trust it more for distance (where the errors get averaged out) than instantaneous speed.

http://connect.garmin.com/activity/68815098

unfortunately the web view jumps from 15:50 to 15:53 and i can't find a way to show the peak. but, it shows the max of 40.2. the image i posted is from training center which is pretty clearly over 40 @15:51.

the reason the peak was so brief was the dork in the minivan who just *had* to pass me at the top of the hill was in my way as i got down by CBW (where it actually gets a bit steeper). i had to lay on the brakes pretty hard (by 15:57 i was down to 31), so it's kind of by luck that i actually topped 40. i glanced down and saw 36 at one point and put in a few seconds of hard effort before i got uncomfortably close and had to slow down. my bike computer showed a max of 41.0.

Nobody's mentioned Verona Rd from Frankstown out to... Nadine? even past Nadine there's not much till you get to the light at Sandy Creek. Granted, nobody but me probably ever rides that because it points straight to an obnoxious hill (which I live on, lucky me). I have no idea how fast I get going, but I usually have groceries, and have on occasion gotten to the point that my "downhill-est" gear did nothing 'cause I couldn't move my feet fast enough (not so impressive if you know my feet, but there it is). If I don't chicken, cars typically won't pass me and don't complain (~30-45? based on what I get driving it). The curves tend to be too much for them, but I can straighten them out (predictably, like taking the lane but weavier, probably not safe at all).

It does tend to freak me out a good bit though, so I usually lean on the brake just enough to make cars want to pass me (~20?). Nice sight lines, though, and exactly where you need them. Assuming someone coming up the hill in a car isn't straightening out the curves too.

Bonus - most cars are so surprised to see me I think they give me more room and leeway than I get in the city. The suburbs' one saving grace.

i accidentally got up to 42 yesterday on federal street yesterday. i was in a half tuck, and braking occasionally. i haven't gone down that street in a long time, so it was unfamiliar. and my eyes started welling up pretty quickly, so i couldn't see.

i didn't even think to try liberty. then again, i don't have any sort of gps equipment.

If you ride in the Mon Valley, you can hit some good downhill speeds at either end of Ridge Road in Jefferson Boro. Either ride down Route 51 and across the Elizabeth Bridge, or Ridge Road drops off of the ridge and into Finleyville at the other end. Both are good clean fun, but riding across the Elizabeth Bridge can be scarier than the downhill.

I was bombing down Hoffman Rd in to Millvale last night after I picked up that tag on Mt.Troy Rd. I got up to 35 and then figured it’s probably not to safe to be going that fast in the dark so I pulled up. I defiantly could have gotten up to 40

@salty - I owe you some beer

after gooski's last night i need a little time before i'm ready to think about beer.

in retrospect, i don't think liberty quite qualifies as "safe" for those speeds - at least not when there's so much traffic. does anyone have a table of stopping distance car vs. bike from 40mph?

OTOH, if there were no cars and someone corked that intersection with herron, 50 might not be out of the question.

i don't know about 50. the difference between 40 and 50 is huge. you could probably do it on federal if you cared naught for your life, but i don't think there are too many hills around that are long and steep enough to hit 50 on.

at least, you'd have to have some pretty serious gearing. mine starts to run out at around 45 mph. maybe that's why there seems to be such a big difference between 40 and 50, come to think of it.

Starting down Federal from the lower Perrysville intersection, with some strong pedaling to get going, I was surprised how fast I was moving by Alpine. Probably not 40, but probably not far from it.

I don't like to be going too fast by the time I get past Alpine; very busy, lots of foot traffic, doors, etc.

The difference between 40 and 50 is huge. I hit 50 exactly once in my life, and I had to go down a mountain to do it.

@salty Check upstream in the thread. Basically stopping power on a bike is ~2/3rds G before you flip over the bars.

And, as I said upstream as well, you're not going to hit max speeds via pedaling:

http://www.yarchive.net/bike/high_speed.html

Yeah - my wondering where you could get up to 50 was more or less how this thread got started...

AFAIK I've never done it, and I don't have any illusions that one can get there by pedaling (well, at least not on a normal bike). But, you can do useful pedaling up to at least 40+ - I just don't know how long/steep the hill has to be to get up to 50 after that.

Suffolk.

Last year my max was 45.3 on Kittaning Pike, followed by 42.9 on a completely unknown back road in WV. Thought for sure I could hit 50 on a 12 mi descent in the Pyrenees, but only hit 42. Road familiarity helps, more so does a certain amount of crazy.

The couple I bought my tandem from claimed to have hit 70 on it. I'm skeptical.

quizbot, I doubt your Pyrenees descent is as long, straight, smooth and clean as the Kancamagus Highway. Also, you're probably a lot less reckless (and a lot more wreckless) than I was at 24.

This thing turns up to 50

Road was 15ft wide max on the mountain descent straights, not much wider in the turns. Some spots there were several 100 ft dropoffs... no playing around there.

When I was 15 or so, nuked Rt 40 from the Summit to Hopwood with a few friends... passing cars, trucks... no idea how fast we were going but probably won't go that fast on a bike ever again.

I hit 36 going down McArdle yesterday - without pushing really hard. It's long, but not steep.

I think this street qualifies as one of the safest since there are no side roads that enter. Last year I was doing 35ish down McArdle when a car had to race to pass me in the oncoming lane, like I wasn't going fast enough.

Hey, sorry to beat a dead horse, but maximum descending speed on a bicycle is an interest of mine.

I'd wager no one on this board is capable of generating the power needed to pedal 40mph. You can certainly *go* 40mph and be pedaling but you'd be better off tucking in that case.

http://en.wikipedia.org/wiki/Drag_%28physics%29#Power

Cubic resistance. That's a lot. Say 200w at 20mph (the very low end) means 800w for 40mph, but no one is achieving 800w seated so the demand is even more since you're less aerodynamic. The hour record is usually achieved with ~400w and that's around 32ish mph.

It's definitely an interesting discussion, and I'd like to know what the best technique is.

I agree there must be a speed where it's better to stop pedaling and just tuck, but what is that speed? Obviously it depends on the bike and rider - does it also depend on the grade of the hill?

I'm fairly certain I can do useful pedaling up to at least 35, and I suspect it may be closer to 40. I'm also completely certain I'm not putting out 800W or likely even 400W (I have no idea). But, maybe I'm completely wrong and I'd be better off tucking at a lower speed. I can't think of an easy way to do a controlled experiment, though.

My fastest has been ~37mph and it was definately downhill. Salty is there anyway to do a "controlled" experiment while flying downhill? (smartass gene manifesting itself again).

Does anyone know what kind of pedal rpms people pull on those un-loaded goldsprint bikes? You could back that rpm into that gearing calculator and come up with a theoretical maximum for pedaling.

I reached 36 yesterday downhill on Steuby pike, on my under-geared, flat bar touring bike with 28 mm tires, not tucked and not drafting, but pedaling. And I am in crap shape. It was getting a little sketchy on that bike, but another 4 seemed to be easily attainable.

I suppose that theres also the fact that I'm on the wrong side of 200 lbs, so gravity is my frenemy.

O.k., so I just got into Sheldons gear calculator to actually check. On my "touring" bike (high - 50-14) I spun out at about 36 mph, and the chart shows 34 mph at 120 rpm. On my "raciest" bike (high - 53-12) the chart shows 42 mph at 120 rpm. That is the bike I reached 48 mph on last summer (behind a well-timed truck, this is WAAAY into "kids don't try this at home" territory). And I still had to do short bursts to stay in the pocket. So the chart jibes with my experience. Shels chart doesn't go any higher than 120 rpm so I would have to do math to figure out what my rpm's were.

The best sprinters in the world can hit high 40's on a track. The winning sprint is most amateur road races with a level finish is under 40 mph. The only way to go really fast on a bike while pedaling is motorpacing. Bikes made for fast motorpacing use taller than average gears.

http://www.flickr.com/photos/56931043@N00/408141814

http://www.flickr.com/photos/56931043@N00/408141829

Taller than average?! There must be 80+ teeth on that front sprocket! Got any operational details on that baby?

I wouldn't say "only way", but... well, to regurgitate wikipedia:

http://en.wikipedia.org/wiki/Cycling_records

motor paced: 167 mph (!)

unpaced, flat: 83 mph

unpaced, downhill: 107 mph (someone posted this video?)

rollers: 208 mph

i don't know what the record is for a "normal" bike on a flat surface; the page gives 56k = 35mi for an hour but obviously instantaneous must be higher.

What does "208 mph" mean on rollers? I've never been able to move mine more than a few inches.

I coast down McArdle at 38 mph and wonder what I could get up to turning a 53 in the front.

I ride the hills on Route 51 north of the Rocks between Kennedy and Coraopolis. There is a saddle hill in between that is longer heading southbound. I coasted down that one at 42 mph yesterday. You can also approach 40 mph heading north - and either has a "run out" stretch with some room (and low traffic) in order to take a lane or ride the middle.

I have a ride with a 53 ring in the front but will wait until it is not so messy outside before pedaling downhill.

I did hit 47 mph going from the Nike site in Collier Township. You could land a plane on that road, although it is tar and chip surface. There is a nice long stretch at the bottom for ease of site (passing cars) and slowing down before the next intersection.

Only somewhat OT, but there was a roadie drafting a Sheetz fuel truck on Neville Island yesterday too. Had to be crusiing at 30-35 mph on the flats. It was quite a site.

50 mph is attainable coming down backside of Greentree Hill into West End - is that Greentree road?

also, Geyer can get it done. With right gearing McCardle as well.

If you want to get to 60+ go out to Ligonier, Altoona or somewhere and you can do it.

Safety? all relative, my friends.

Just had a cyclist killed bombing down a relatively "safe" descent in tyrone, pa last summer.

Dude, there is a stop sign at the bottom of Greentree. That intersection almost always has traffic too. Not a good one, but I hear what you are saying about the slope.

..yes, gotta have good brakes if yinz wanna go fast (kinda an oxymoron, huh?)

you'll hit terminal velocity before the RR overpass on Gtree hill. - so there is plenty of time to slow for the stop sign.

Ok two things. First, I've been climbing 885 up to century III for work lately. On my way down it is easy to hit low 40's without even trying. There is a traffic light mid hill, but other than that it's fairly driveway free (eh, Big Bang), and not too bad on holes.

Second, the top of Glass Run Rd. in Baldwin has just been paved but remains closed to cars - hurry while it lasts.

Hit 45 on Kittanning Pike again last Sunday. Becoming quite familiar with the road, doing repeats for etape training. 50 mph is definitely possible but I sketch out on letting it go at the top where it's steep because of the 4 or so blind intersections till you pass Cottonwood. Also, critters crossing the road. Do not want a groundhog running thru your front wheel at speed.

@salty, I still owe you some beer!

Ha, i almost forgot about that... now I think you can see how I utilize my superior mass-to-frontal-area ratio to hit high downhill speeds

According to the computer on my mt bike I have had it to ~48 with street-ish tires and a big hill. Speedo was confirmed @ 20 mph with a car side by side (probably not the safest). I find the GPS on my phone can skip tracking points and the built in error can yield some outrageous speeds.

Dwellington Drive off of Rt 8 in Valencia, just over the Butler County line.

Ooh man, Glass Run road, I used to bomb that road on a sport bike (motor). It was a beautiful thing.

Aerodynamic drag chart. Looks like if one drank enough beer, one could acquire partial fairing. Needs to be tested in the field.

@steve k: Where was that?

Do those max watts even put you above "untrained" in WKO+?

@Quizbot Coxcomb Rd today.

http://connect.garmin.com/activity/94958916

48.8 on dirt roads.

Not really local, but my land speed record (54 mph) was set on Albany Hill, which anyone who has ridden the Mon Valley Century will recognize. I hit 45 regularly on Battle Ridge Road in South Fayette, and on Segar Road in Mt. Lebanon/Scott Twp.