Fat Boy Biker

Coming down a long hill, semi-drafting behind a wiser and more experienced cyclist who let me ride with him today, I set a new personal best for max speed on my Bianchi. A blistering 46.5mph. And what's more, I chickened out and started hitting the breaks when there was still more room for acceleration. How fast can I reasonably expect to go? Assuming I'm willing to clean out my riding shorts (well bibs actually) at the bottom of the hill.

Steve
-need for speed? maybe, I still a bit unsure

go4broke44

sucky thing about bikes is that you can't detect speed wobble until you're going too fast to be able to do anything... my personal best is 48.8 mph, downhill, but then fell victim to the wobble and went over... at 48.8mph, road rash hurts!

Fat Boy Biker

Ouch!
That doesn't sound very encouraging.

Steve
-that's gonna leave a mark

clfjmpr44

Living in Northern Virginia, my regular routes don't leave too many prolonged downhills. I am one to throw cation to the wind, but I have only gotten to 31 mph. What kind of hills are you guys producing 46.5 and 48.8 mph on? How long are they?
Also, I have to know, going down at 48.8 has to leave you with something to remember it by, what werre the circumstances broke?

26mi235

I have gone about 55 or so, with many, many times in the 40s. It depends on the route and the circumstances. Off the north side of Blue Mounds there is a long, steep drop with a good runout. With some people strung out in front it is safer because you are less likely to get surprised by something on the road. When they did the State Road Race on that route several years back, one of the riders in the lead break did have a problem and crashed at 60mph. It was not a blowout, as the tires were intact.

Personally, I have never had a high-speed wobble, but with a new bike I will ease into higher speeds. Also, I have a different threshold now than when I was younger and have not done 50 in a while (I am mid-fifties). I did have one high-speed crash, but I had shed speed from 40+ down to 20 or so when I went down (I rode to the next check point but that was the end of that century ride).

flyingasics

Not many hills around here in Auburn, ya have to go to pine mountain in Georgia to get anything that you could get that fast on. Although I did catch a draft from a semi a few months ago and hit 54 mph . No death wobble on my Giant OCR 2 though, thank God.

Fat Boy Biker

Living here in Colorado, it's pretty easy. We have so many hills here, my front break pads are noticeably more worn than my rear pads. And I have had the bike only 2 months and about 400 miles. I think the hill I was on today was probably about 2 miles long. The steepest part is probably an 8% grade (just guessing) for about 1/2 mile or so. Like I said, I chickened out. I have no doubt I could have hit 50mph.

Steve
-The fastest that you can stop any bike of normal wheelbase is to apply the front brake so hard that the rear wheel is just about to lift off the ground --Sheldon "Front Brakes" Brown

531Aussie

55mph down a very steep hill on my Cervelo -- no wobbles, no nothing, just a bit of anxiety

redfooj

the hill where i hit 54mph on was probably about 250 yards long...it was preceded by a long portion with a very slight decline, but the last 200 yd was a SF-like drop.

it actually wasnt scary the first 2 times i rode on a large stable bike (semi touring geometry).. but the last time was on a bike with normal geometry and it make me really nervous half-way down (because the steering was way more responsive)

what's crazy was that a friend--who is not a biker--wanted to come along on one ride... we handed him a clunker that was 4cm too small... the rear wheel was missing a spoke, and it had only a front brake with pads that were literally 10 years old. he bombed down that hill with us. we didnt realize the circumstance and what he did until after the ride... lucky we had a green light at the bottom of the hill (it runs by a freeway )

TheKillerPenguin

Going fast down hills is a lot of fun, if a bit scary. The local climb is 2.2 miles 9% avg grade...at the top is an insane 90* turn that must be at a 15% grade...you go around that and you feel yourself being compressed into the ground as you go around the turn. There's a 1-1.5 mile straightaway a little bit farther down it, great for going aero and peddling your arse off. But nothing beats that first turn. Scares the crap out of me every time and I love it

lilcog

91.3kmph Foymount,Ontario Canada.Not a very long hill but has a bit with 16% grade.It was a blast.

DocJ

My fastest time is 9.8 meters/sec... straight down. Happens more often on the mtb.

go4broke44

i was in the boston beanpot road race about a month ago, it was 500 vertical feet stretched out over a mile climb, followed by a 500 vertical feet over a mile descent. UVM was pulling the pack up the hill, and riding fairly slow, 10-14mph, i assume to weed out the pack on the climb. almost to the top, they took off, pulling the first half of the pack away from the back half. i was boxed in, so i had to wait, and coming over the hill i broke free and was basically 53-12 pedalling all the way down the descent, i actually did catch the tail of the lead pack, which was about 50-100yds ahead of the tail pack that i was in. i started getting speed wobble towards the bottom of the hill, so i started braking to try and control it, but hit a rough patch of road and i guess the front brake grabbed, all i remember was slow motion nose wheelie, and kinda being in a blissful state, then thinking "oh ****, this is gonna hurt" and it was basically fast forward from there through a scrape and roll. i had figured i took down people with me, but there was actually a crash ahead of me with 2 people, and one behind with 3, another person came up and ran into the front crash, after almost hitting me as i tried getting off the road as fast as possible. i ended up breaking my seat (selle italia octavia, i really liked that seat), and totalling my front wheel, and somehow the back wheel came loose and was another 20-30 ft down the road. luckily, we all crashed right in front of where the ambulance was stationed, and the guy's lawn we were occupying was an ex racer, who was really cool and even showed us his old bike. out of the 7 who crashed, one got treated and got back on his bike, 3 went to the hospital immediately, and the rest of us got a ride back to the start/finish area. i think i had the worst case of road rash, there really wasnt anywhere on me that was un-rashed. it didnt hurt that much until i took a shower that night, ended up going into shock, and had to go to the hospital where they gave me nice drugs and had to brush/scrape the dirt out of it all. made for a painful week when the meds would wear off, crashed on saturday, and was back on the trainer tues night, haha. didnt go back to class til the following week though. i think speed wobble is derived from faulty manufacturing of equipment, basically if one wheel isnt exactly in front of the other, or at least thats what someone told me. kinda makes me nervous to try speeds again, even though i got new wheels. but like everything else, time will heal all i guess...

cryogenic

I wonder how many people will get this one.

DocJ

You did. Besides, I'm the fastest so far.

my58vw

Last Sunday I hit 51.2 MPH down a 8 percent hill, I think at 2 miles long or so. I could have gone faster but group was getting scared and the road was not straight.

UmneyDurak

Nice acceleration.
My fastests was 50 mph, down some hill.

Colorado

yeah, except it is 9.8 m/s^2 which isn't a speed at all.

DocJ

Yeah.. I know. Just too lazy to add the squared figure. That's what I get for being a smarty-pants.

my58vw

That is acceleration... duh! Now if you fell at g for some time you may reach some terminal velocity over 50 MPH

I also had a new max speed tonight. Second light to light sprint, 25 seconds, 33.1 MPH.

redfooj

actually, it cant happen more often on an mtb.. since it happens all the time

Rowan

We can but wonder why...

BryanW

My highest is 55 mph down a 1 in 7 (14%) after aero-tucking behind another rider and then drifting out past him. No point trying to pedal at that speed.

What causes high-speed wobble? Can you tell in advance if a bike is likely to have it? None of my previous bikes have suffered from this, but I'm just about to get a new one and I'm worried that it'll have it - my favourite bit of road-riding is high-speed descents (especially when there are corners )

lisitsa

9.8m per second is only 36 km/h (22mph).

TrekDen

BryanW,
I wouldn't worry about it on the new ride. High speed wobbles usually come from loose hubs, headsets, and most come from under inflated tires. Check that tire pressure often to keep it in check.