Vibration like feeling while pedaling

[Kajjal]

When I have had this the causes were :-

pedal bearings needed tightening and regreasing
front headset bearing gone, replaced bearing
loose Chainring bolts
front mech cable end rubbing on tyre
rear wheel bearing gone, ending up replacing both wheels good excuse ( take wheel out of frame and spin it was easy to spot.)
rear wheel bearing loose and needed regressing.

Generally speaking the more power / effort put in to pedalling such as up a steep hill or sprinting the worse it was.

 

[Brooks]

I'm more than sure it's the Arsenal bracket!

 

[gbb]

Has the previous owner or supplier fitted a new chain ?
Quite a few times in the past, when ive fitted a new chain to an existing chainwheels and cassette setup...i got a mechanical whirrr.
Iif thats whats happened in your case, it will pass with a few rides, i think its the slight mis match between new chain and worn sprockets....its just bedding in.

 

[silva]

There is a tensioning up and down, which indicates an out of center and/or a concentrated wear somewhere, an idea could be "repositioning" the chain on the mostly used ring, ie rotate a crank to an easy to identify pedal position, mark the link on top of the mostly used ring, then losen the chain, then select a chain link (ring teeth number divided by 4) away, and place that link on the top position.
Another option is to rotate the position of the chainring(s) on its mount (spider).
Check the chainring teeth for sharkfin shaped series. Those make it harder for links to disengage, and aggravate this wear.

 

[Weyland2k]

Hey,

Got a fairly new bike, and for the past few rides I noticed this weird vibration (like slightly more and less resistance feeling) while pedaling. Haven't noticed it before much, as it's being apparent only on higher gears while riding fast on a smooth surfaces (more than sure it's there regardless of surface, just being masked by roughness of terrain). I went to a nearby bike mechanic, he gave it a checkup and told me that mechanically everything is all right. He suggested it might be due to chain being more tense on higher gears, and this is just how my cycle is working (agree it's not most expensive high end bike, but it's not that bad either. At least I hope).

Today I had some more time so I cleaned drivetrain, applied fresh lube and checked it again. Vibration is still there, and after putting my bike upside down to check if anything is visibly wrong while wheels are spinning, I could definitively feel it while spinning pedals with my hand. It's way more intense on higher gears, but it's still there on the middle ones. I don't think it's related to the specific sprockets (that's how the gear wheels are called right?), as the transition in intensity of this feeling is smooth rather than a rigid one.

Do you have any idea what might be causing it? I already cleaned everything and even applied fresh grease to the pedals. Should I just go back to the bike shop with it, or I'm exaggerating and this is just how it is? I would just like it to be a smooth ride, not annoying one.

Appreciate any answers.

my bike info:
Bike is Marin Fairfax 1, alloy frame with rigid fork.
DERAILLEUR, REAR - Shimano Tourney, 7-Speed
DERAILLEUR, FRONT - Shimano TY510
BOTTOM BRACKET - Sealed Cartridge Bearings, Square Taper
CHAIN - KMC Z50
CASSETTE - SunRace 7-Speed, 11-34T

Did you end up figuring it out? I got a new bike last week, started vibrating and now the entire frame squeaks!! I just need a simple bike man!!

 

[Ajax Bay]

Did you end up figuring it out? I got a new bike last week, started vibrating and now the entire frame squeaks!! I just need a simple bike man!!

I'm afraid @Camus47 was only 'here' for a week in 2021: not seen since!

 

[Yellow Saddle]

Drivetrain vibration is often due to worn chainrings and or worn sprockets. However, the latter only applies to singlespeed bikes because a worn cassette will cause chain skate on a derailer bike where the jockey limits the tension on the return run of the chain circle.

If yiour bike is a geared bike, look at the shape of the chainring teeth. Take a nice side-on photo of the chainring with which the vibration is associated and we'll take a look. Make it clear of chain when you take the photo and use the focus feature on your camera please.

The vibration is caused by the sprocket teeth (called cogs btw) are out of pitch with the chain. The incoming tooth (cog) then clashes against the incoming chain roller on the chain and is forcefully pushed in, causing a vibration at the same frequency as tooth engagement/cadence.

On singlespeed bikes this is more often than not caused by a rear sprocket.