capeofstorms Posted September 25, 2012 Share Hi, Coming down Suikerbossie from Llandudno side at around 55km, my bicycle started wobbling violently for no apparent reason. I barely managed to bring the bike under control. Needless to say, I was pretty shaken. Upon inspection, both wheels were securely tightened and the headset showed no signs of play. As a precaution I took both wheels out and fitted it again. Anyone experience this and if so did it happen more than once? Link to comment Share on other sites More sharing options...
Kranswurm Posted September 25, 2012 Share Hi, Coming down Suikerbossie from Llandudno side at around 55km, my bicycle started wobbling violently for no apparent reason. I barely managed to bring the bike under control. Needless to say, I was pretty shaken. Upon inspection, both wheels were securely tightened and the headset showed no signs of play. As a precaution I took both wheels out and fitted it again. Anyone experience this and if so did it happen more than once? I picked up a wobble once at 70k's.gripped the down tube with my knees and it was gone. You must have done something on the bike like shifted your position to cause an imbalance Link to comment Share on other sites More sharing options...
The Saint Posted September 25, 2012 Share Speed wobble I think has more to do with the bike than anything else. I have owned a few Raleigh bikes and all have been unstable whilst going downhill, now ride a BH and no such problems. I have also heard that sometimes changing the front fork can cause the bike to become "out of sync" as such and allow it to become prone to wobbling, not sure if this is true or not but maybe something to consider if you have made any such change recently. Only advice I can really dispense is that when the wobble starts grip to top tube with your knees it will help to stop the wobble. Edited September 25, 2012 by The Saint Link to comment Share on other sites More sharing options...
HappyMartin Posted September 25, 2012 Share Also had a Raleigh that wobbled like a wet noodle. Grip the top tube with your knees as others have said and lift your bum off the saddle to get your centre of gravity lower. Take the weight off your hands, shift your weight back. DO NOT TOUCH the front brakes unless you want die. Oh and good luck Link to comment Share on other sites More sharing options...
Kranswurm Posted September 25, 2012 Share Also had a Raleigh that wobbled like a wet noodle. Grip the top tube with your knees as others have said and lift your bum off the saddle to get your centre of gravity lower. Take the weight off your hands, shift your weight back. DO NOT TOUCH the front brakes unless you want die. Oh and good luck :lol: Link to comment Share on other sites More sharing options...
Gunzo Posted September 25, 2012 Share Hey..., just need to come up for Raleigh. My previous bike was a Raleigh and my top speed was 92 km/h without any wobble.In last years Clover Lowveld tour, one of the guys had problems with wobbling. He rode a Spesialized. But I know the knee clamping trick worked for him. I do think it has to do with the overall geometry. And the geometry differs greatly between brands and between models. Link to comment Share on other sites More sharing options...
Shebeen Posted September 25, 2012 Share it's called 'shimmy' and is f@#$off scary. good advice here so far. [sortKey]=date&search_app_filters[forums][sortKey]=date&search_term=shimmy&search_app=forums&st=0"]https://www.bikehub.co.za/index.php?app=core&module=search&do=search&andor_type=&sid=b1f7150ce3e174e80f6aa04caffb76ee&search_app_filters[forums][sortKey]=date&search_app_filters[forums][sortKey]=date&search_term=shimmy&search_app=forums&st=0 Link to comment Share on other sites More sharing options...
rudi-h Posted September 25, 2012 Share only thing that can make your bike wobble is a serious imbalance in your wheels, but even that should only happen when you sit upright and ride without hands. Is it an MTB or a road bike? Cannot imaging this happening 55km/hr though, especially if your hands were on the handlebars... Link to comment Share on other sites More sharing options...
kosmonooit Posted September 25, 2012 Share Aah the dreaded resonance! http://youtu.be/P0Fi1VcbpAI And you thought you had it bad ... Link to comment Share on other sites More sharing options...
Dirtbreath Posted September 25, 2012 Share Harmonics. By gripping the top tube with your knees you dampen the resonance through the body (bike and rider) and break the perfect wave which has been set up and increases in amplitude, ie a massive wobble. Link to comment Share on other sites More sharing options...
HandH Posted September 25, 2012 Share Hey I used to get that on my skateboard,.... all the time......Used to stop the wobble by hitting the ground very very hard....... Raab and carbon29er 2 Link to comment Share on other sites More sharing options...
ChUkKy Posted September 25, 2012 Share Hi, Coming down Suikerbossie from Llandudno side at around 55km, my bicycle started wobbling violently for no apparent reason. I barely managed to bring the bike under control. Needless to say, I was pretty shaken. Upon inspection, both wheels were securely tightened and the headset showed no signs of play. As a precaution I took both wheels out and fitted it again. Anyone experience this and if so did it happen more than once?Faaark, I think I would have left a stain in my bib and have to throw them away immediately. Link to comment Share on other sites More sharing options...
Scotticus Posted September 25, 2012 Share Hey I used to get that on my skateboard,.... all the time......Used to stop the wobble by hitting the ground very very hard.......Like yooorrrrr! I remember those days. Hanging on the back of a bus on your skateboard.... the "Wobble" - vrek scary, but yet we did it again. Link to comment Share on other sites More sharing options...
LeTurbo Posted September 25, 2012 Share Yup, also on Suikerbossie, and braking just seems to make it worse. I got the crossbar-between-the-knees advice as well as the counter-intuitive take your bum off the saddle. Unfortunately, I can never go down Suikerbossie full tilt anymore. It's all psychological. Link to comment Share on other sites More sharing options...
Audible Anarchy Posted September 25, 2012 Share https://community.bikehub.co.za/topic/107379-speed-wobbles/ i had this problem with a new frame last year - scariest freakin thing ever - makes you lose all confidence on your handling ability! i managed to sort it by moving my position forward a bit with a longer stem and moving the saddle to get the weight a bit more over the bars. i still lift my bum a bit and rest my one knee on the top tube to be safe though! Link to comment Share on other sites More sharing options...
David Marshall Posted September 29, 2012 Share The resonance can be set off by anything - finding the exact cause is difficult as changing anything that affects the set up (stem length, wheels, fork etc) can cause it to stop, even if that component did not set it off in the first place. I 've noticed that rider tension can be a significant factor in the onset, even just shivering from cold! It can happen to any bike and a bike that shimmies with one rider at 50 km ph can be rock solid with another at 100km ph. It has to do with the combined rider/bike set up. It is not a brand or cost thing - put any bike on a workstand, turn the crank and see how quickly the lack of balance becomes obvious. If your bike set up is right and everything is in good shape and you still have a problem, time for a change - it is not worth that feeling every time you descend. Link to comment Share on other sites More sharing options...
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