my58vw

Hello all,

I just got back from a group ride out to Sunset loop in Redlands California. Well I had a "small" mechanical problem along the way. Going to the start of the 5 mile climb we go up about 2 miles of mild climbing then there is a big downhill. Well I was towards the back of the group after the climb (my usual pace, I climb at my own tempo which is about 17 MPH here if you can count it as a climb...) and we aproach the downhill. It is very very fast and quite fun but it is a little bumpy and cars are always coming up the other way.

On the downhill I am in my tuck in the drops passing everyone as usual (being 225 lbs is good for something ). All the sudden I go around a guy and something happens and my front wheel starts shaking violently. At this time I was doing about 48 MPH and had NO control of the bike. The bike shot over to the other lane of traffic as I frantically tried to regain control. I tried to lean over and the bike shifted, barily missing going in the dirt. I hit a pothole and nearly went over the bars as I came to a stop.

By the time I got stopped the group with the "no drop" policy was long gone. I ended up finishing part of the ride but the whole thing shook me up for a few minutes after. I have no idea how I kept the bike going forward, the wheel was really trashing on the decent. I looked at the computer and it said 48.2 MPH max after the decent, that is nearly 80 Kph...

I am curious though how many people have had something like this happen? I took the bike to the LBS and they tightened the headset and put in some new bolts in the stem. They could not believe how this happened. Of course I have 2k miles since last time the headset was looked at.

Crazy...

duane041

Now THATS scary! Glad to hear you made it out OK.

Maybe this is what is wrong with my bike. I finally hit 33 MPH today (on a flat, which for me is a HUGE deal), and the bugger was wibble-wobbling all over. Only way to stop it was to slow down. Nothing else helped.

That'll teach you to go almost 50!!!!

-titanium-

duane041 hitting that speed should not make your bike wobble! I think maybe because that sounds like a substantial speed ot reach on a flat, it was probably your frantic pedaling that shook up the bike in your case! Or where you sprinting out of the sadle? because that always gets the bike going from side to side nicely.

ViperZ

Scary speed wobble Good job and nice handling skills to keep it in check.

If it wasn't the head set, maybe the wheel hit something that started the rim and spokes to oscillate?

lilHinault

You have to RELAX as counterintuitive as that is, and stay down, and let your "dead-ish" arms absorb the oscillations.

Hard to do in the split-seconds it happens though, I had my faithful Yamaha SRX-6 do the most amazing tank-slapper on the freeway, I think triggered by ruts in the freeway (yes I was going freeway speed) and when it happened all I could do was sit there and witness it happening, it ended and I pulled over after a bit and checked out the brakes and general front end, all looked OK and I went on home, it was already turning out a lousy day, since my license plate had fallen off.

Dchiefransom

Touch a knee to the top tube if you can. The husband of a woman I know could not get rid of the wobble on his bike. They got him a different bike. I've heard of this happening before, and they can't find what's causing it. On fast decsents, it can happen every time with some bikes. Be careful.

zonatandem

Could be harmonic vibration. Totally scary!
No known 'cure' but here are some tips:
DO NOT touch the brakes or you'll automatically crash; clamp both knees to the toptube/or lift butt off saddle. Usually will subside as speed decreases.
Have had 3 single bikes and 1 tandem go through harmonics. Sometimes insufficient rake of fork can cause this under certain speeds/conditions.
Outrode all of the harmonics, except the last one. Descending down a canyon on a curvy, but newly asphalted road surface, at 38 mph on a Ti Merlin single bike. Harmonics started and reacted by clamping knees to toptube (no luck), sitting upright to scrubs some speed and finally was slaloming all over the road and even into oncoming traffic lane. Not being able to see around the next bend, decided to tap front brake lightly and knew I'd crash. Did my paratrooper roll over handlebars spreading impact forces over shoulers/back. Fractured right shoulder in 2 places.

late

Hi,
let's assume you have frame flex. This is a well known cause of high speed trouble. You a big guy on an older bike? That can do it.
Consider this potentially lethal.

duane041

I certainly was pedaling frantically, but the wobble came from only the front wheel, even when I started coasting. I could see the stem/bars shaking from side to side. I did notice, on my way home, that if I am riding no hands there is resounding "clank" from the headset when I would hit bumps, even small ones. Maybe it's time to have the headset looked at? I did buy the bike at a garage sale, so who knows....

jslopez

Have you hit that speed before? Where there any outisde factors that changes (strong winds, vehicles passing etc) ?

my58vw

Many many times, I would say that I have hit speeds of 45 MPH+ at least 100 times this season, particulary on this and other simular stretches of road. The fastest I have been on this bike is 61 MPH on a long straight downgrade with no problems. I have also been in some nasty crosswinds with the deep dish wheels and this feeling is nothing like that. With wind it feels like you are going to be knocked over, not shimmy.

I guess the road could have had something to do with it but it would be unlikely. It was a calm day, a mild crosswind at best, no traffic whatsoever (thank God on that, I could be dead if I would have hit a car head on at those speeds). I think the conclusion can probably be linked to the headset coming loose. I may have hit a bump just right to cause it to happen or tip it over the edge.

I have put enough time on the bike (over 4k miles total) to know what it feels like and I have never had a lack of confidence in its ability to track down a hill or in the corners.

R600DuraAce

I love my Orbea. Things like that do not happen to my bike. If the descend is long, I could ride with one hand and the other could be grabbing a water bottle or some food. All the hilly races I have done 45 mph to 50 mph is the norm when comes to descending. Glad you are ok.

Olebiker

I have seen this happen twice. The first time was a young woman on a cheap bike at Land Between the Lakes in Kentucky. The next time was my friend on his new Serotta Colorado about ten years ago. I have never seen a definitive answer about why it happens. The friend is still riding the Serotta and it hasn't happened again.

MasterSezFaster

All it takes is one tiny little bump or crack in the ground that if hit just right will cause the wheel to start shaking/vibrating. Once that starts it is very hard to correct until you get your speed down. It can also happen if either of your tires loses traction for just a split second and then when they regain grip it sends the bike in to a high speed wobble. We call this a "tank slapper" when on a motorcycle.

They can scare the shyte out of you if you have never experienced one before. I have seen a lot of good racers (bicycle and motorcycle) go down hard because of it.

There are other reasons but the above seem to be the major causes when equipment/component failures are ruled out.

Thylacine

I've been involved with many discussions about harmonic resonance, and what I've come to believe is that a) It can happen regardless if the conditions are right to induce it, and 2) Steering geometry and frame alignment/geometry in general can reduce or eliminate it.

The thing is for me from a bike design perspective, is that a design that feels good at 15mph is often not a design that feels good at 50. Also, as a tall guy my58vw, what fits you and works at speed is not the same as what works for some shortie on some mega short wheelbase.

For example, I'm 6ft 4ins, and my bike (which has numbers that couldn't be more different to ANY off-the-shelf bike) doesn't feel optimal at slow speeds, but the faster you go, the better it feels. Doing 84kph out the back of Gisborne and it felt like I was standing still.

retroBMX

Not speaking from experience here, but I have read that misalignment of the fork dropouts can cause this. I would suggest having a top-notch LBS check your fork and frame alignment.

marty_vee

Once again you are full of $hiT! I have done that ride many times and there is no way you can go that fast at any of the corners let alone on the few straight downhill portions with out hitting something at the bottom. Dont forget that I watched you almost crash on that descent at 12mph.
Maybe you should take the second pickup off of your spokes to get the ACTUAL speeds...

go4broke44

its called speed wobble and its due to your frame or fork being out of alignment (manufacture defect) i went down at 50mph due to it, thats some nasty road rash
im still waiting on a replacement fork from raleigh

hi565

marty, WOULD YOU CALM THE **** DOWN! He didnt do anything. Please there is no need to get pissy right now. Jeez!

my58vw

Marty,

Do you even know what decent I am talking about... NOT SUNSET! Max on Sunset is about 30 - 35 MPH. I am talking about the decent on the back side of barton or what ever street that is going to the road that goes directly into Redlands. Plus I do not know what the HELL you are talking about with the 12 MPH *****.

I climbed SUNSET 3 times this week in training for a race coming up... do not give me crap about once again you have no idea about. You are sure good about taking about a minute amount of facts and twisting them into 50 pieces. Get your facts straight before you come on here trying to start *****...

Once again you have no idea...

BTW I have decended at nearly 100km (60 MPH) on a very long steep decent. Shoot I have almost hit 50 MPH coming off of Tyler going to Magnolia (10% for about 500 feet maybe). Let yourself talk Mr... I am going to ride the bike with a cheep ass messed up headset, flexing fork, etc. It could have been you many times over... what a shame if your F1C got hurt...

Drop this because I am not starting another flamewar with someone who had NO idea what happened.


Back on Topic...

I am going out tonight to do some more hill training (Sierra) so I will see if everything is ok. I do not know if it was a headset that was causing the problem but it seemed quite stable this morning on my ride. It could have just been a freak thing also.

Decending is always a dangerous thing and freaky things can happen. That is when experience comes in handy to be able to get out of them as good as possible.

JavaMan

Keep your weight forward. Grab the top tube with your knees.

edit - Probably nothing wrong with your bike, except that large frames don't have much trail built in. By the way, motorcycles do it, too. So do shopping carts.

marty_vee

You were talking about sunset and those speeds on sunset. Maybe you should get your lies straight. If you mean something else, you should clarify it. Get YOUR facts straight.
.
.
Once again, you should clarify WHERE. Do you intentionaly mislead everyone or does lying just come natural?
That is hilarious that you are so immature that you have to try and insult me by talking about my bike.
You should call me ugly and stick your tongue out, it would complete the visual of your screaming tantrum.
Grow up little lady, wipe away the tears. I know it hurts when you get called on your lies but try to contain the fierce crying.
Perhaps you should go turn your pedals in anger again. LOL

Oh, and by the way. You started the *****, Im just giving it back.

.

my58vw

I do not read anything you post so stop posting and get out of here. I am tired of your harrasment. That is all that you do and harassment has no place on this forum. Your posts have been reported to the moderator and to site admin. I will not entertain any more of your posts so this is the last warning.

I am sorry that we can not be more corgale about this but you are acting like a baby. I will no longer reply to your posts on my threads including this one.

It is stupid that someone like you will just absolutly ruin someones riding experience. I have lots of friends in the club, and I would like to ride with them. Your childness is depriving people of that. I had a good ride Sunday because someone was not there harrassing me. That is all, consider this over.

(Mods sorry this is not in pm's but someone had to bring it out into the open forums again, feel free to lock this thread).

jit2

Marty,

Give it to us straight.

Once and for all. People actually seem to listen to this noob. Let them know who they are taking their advice from. I know from experience that most of his claims are just BS, and the rest are suspect at least. But I think it is time to let other forum members know the truth.

Can this guy really ride or is he just massaging his ego with all these self-centered posts? Will his treasured bikes, in your opinion, end up collecting dust on the wall of his parent's garage once he loses his enthusiasm for the sport? It has to be demoralizing having your ass handed to you on a platter every time you line up for a race, I know it would take the wind out of me.

my58vw

How would this idiot know. In the maybe 10 times I have riden with him it has been hell. I would take his opinion with a grain of salt. I have...

1. Never seen him at a Race
2. Never seen him at a hammer ride I have done
3. Never seen him without an EGO!

How would you know how someone rides if you never go and ride with that person. That would be like me saying... jit2 rides like crap, he can not go more than 14 MPH and walks up all hills. Since I do not know you I could never say that. Obviously this guy has NEVER seen me race, NEVER been on a training ride with me, etc. I am personally would not invite him.

Ask anyone here on the forum who has raced with me... I am not a poseur, I go and work my a$$ off all the time, one persons jaded opinion can not change that...

That is all.