Vibration at speed

[mrmacmusic]

Given last weeks winds, I didn't achieve any great speed on my commutes (going for 5 days again this week, so hopefully the wind fairies aren't too mischievous!). However, the past few times I've gone over 30mph I'm sensing vibration and a rumbly sort of humming/buzzing noise.

I'm not sure if this is coming from the tyres, or the hubs, or if it is perfectly normal or not... I've definitely not noticed it before now. The (admittedly very basic) wheels on my Ridgeback Fight 01 have remained exceptionally true in the few months I've owned it, so I don't think wheel trueness is a factor. Any thoughts?

I also wonder if having just crossed the 1000 mile barrier if I should be doing any sort of maintenance on the hubs? At the moment my weekly routine just involves cleaning and lubricating the chain/drivetrain, checking the tyres, and making sure the brakes and gears work fine.

Sorry if this is just another noob question

 

[fossyant]

Free wheeling or in power ?

Can be all sorts. Where is the vibration coming from ?

Tyres - these buzz if you are running any trail/off road type. Slicks hiss.. race tyres and latex tubes sing....

 

[Garz]

When exceeding great speeds on my old boardman it made a hard to describe sound - if amplified I guess similar to having ladders on your car/van on the motorway. This was down to getting low and hearing the brake cables/frame shape you could actually hear the airflow. Probably not what your on about but I went off on a tangent there...

 

[accountantpete]

Could be the rims being vertically out of true. It doesn't take much at 30mph to generate vibration.

 

[mrmacmusic]

Thanks folks - I can't identify where the vibration/noise is exactly coming from, but it seems to occur whether freewheeling or under power. Going to pay closer attention on tomorrow morning's run (assuming I get up to speed!!).

I guess my concern was worn hubs (or grit) given my other question regarding maintenance.

 

[wheres_my_beard]

Could be the rims being vertically out of true. It doesn't take much at 30mph to generate vibration.

+1 Roundness could be the issue.

What kind of brakes do you have? The reason I ask is that on my previous bike the disc for the disc brake was very slightly bent and would rub on the brake pads very slightly, but at high speed it sounded aweful, having made no noise at all at low speed. Your fault could be something similar.

 

[mrmacmusic]

+1 Roundness could be the issue.

What kind of brakes do you have? The reason I ask is that on my previous bike the disc for the disc brake was very slightly bent and would rub on the brake pads very slightly, but at high speed it sounded aweful, having made no noise at all at low speed. Your fault could be something similar.

I don't have discs, so that's one less possible cause! Will see what happens on tomorrow's commute, but it sounds like I need to give those wheels a thorough check.

 

[Oddsos]

Tracking down the exact cause of funny noises is a real art. You end up having to isolate each different moving part. Often the noise/vibration comes from somewhere totally unexpected.

To eliminate the hubs try removing the wheels from the frame and spinning the wheel whilst holding the axle. You should be able to feel if there is a problem with the bearings. Ideally the wheel should feel silky smooth as it rotates. If it feels a bit rough you may just need to lubricate the bearings. If it feels really rough you may need anything from new ball bearings to new hubs.

 

[Fab Foodie]

Sometimes the tyres can be slightly out of round too or not sat properly on the rims. My rear Pro-Race 3 was very slightly uneven and it was only notable at speed on smooth roads.

 

[wheres_my_beard]

Tracking down the exact cause of funny noises is a real art. You end up having to isolate each different moving part. Often the noise/vibration comes from somewhere totally unexpected.

To eliminate the hubs try removing the wheels from the frame and spinning the wheel whilst holding the axle. You should be able to feel if there is a problem with the bearings. Ideally the wheel should feel silky smooth as it rotates. If it feels a bit rough you may just need to lubricate the bearings. If it feels really rough you may need anything from new ball bearings to new hubs.

Your frame will be transmitting the reverberations from it's source (your wheels are spinning at just under 400rpm at 30mph if my maths is right) all over you bike and back again, possibly mixing with frequencies coming from other areas/ components to produce what you can feel and hear.

Considering that this is happening whether or not you are pedaling suggests that it is something to do with parts that are moving at the speed the noise is being produced or parts that are in direct contact with them:

1. wheels - totally round and true?
2. tyres - are they installed perfectly evenly (round and true also?)
3. inner tubes - are you using tubes that have been repaired? This can cause flat spots where rubber cannot expand as mush as surrounding area due to the patch
4. brakes - rubbing on wheel or tyre? won't be an issue if 1. and 2. are not.
5. Hub - bearings in tact and running smoothly?
6. Axle - straight and true?

 

[mrmacmusic]

Thanks for the excellent advice everyone – much appreciated

I didn't get above 25mph this morning, so didn't experience the same vibration or buzzing – in fact, this mornings ride seemed smoother than normal, and was the first with my new pannier bag on (full of change of clothes, lunch and tools). Weird.

 

[zacklaws]

For a quick check that the bearings are OK, lift the wheels off the ground and spin each one in turn and listen to them with your ear tight to the frame or saddle, if anything is amiss you'll soon hear them crunching or grinding. If the sound is even and smooth, they are Ok if its loud and uneven, then the bearings are dry or worn out and need overhauling. For the back you may need to remove the chain so that will stop the freewheel clicking

 

[mrmacmusic]

For a quick check that the bearings are OK, lift the wheels off the ground and spin each one in turn and listen to them with your ear tight to the frame or saddle, if anything is amiss you'll soon hear them crunching or grinding. If the sound is even and smooth, they are Ok if its loud and uneven, then the bearings are dry or worn out and need overhauling. For the back you may need to remove the chain so that will stop the freewheel clicking

Thanks for the tip