The sound stops when I don't pedal. It is most bizarre, like someone tapping lightly on the frame with a hammer, as you can see/hear here:
I took it to the bike shop and they tightened the bottom bracket, but that didn't fix it.
- The noise only happens in 4th or 5th gear for some reason.
- Only happens when pedaling.
- The knock is associated with the revolution of the pedal.
- Happens even if I stand and pedal (i.e. not seat-related).
- I can't reproduce it on the bike rack. Apparently, there needs to be some torque/weight.
- I checked the chainring bolts, they are not loose.
- It happens regardless of which ring the chain is on on the front derailleur.
I am at my wits end and would appreciate a tip.
The knock sound is there even if I pedal without touching the handlebars.
"Does it change speed when you change gear" - The speed is associated with the pedal revolution. Regardless of the gear, there are two knocks per revolution.
"What if you pedal backward" - Then there is no knock sound
"small arc" - Impossible to test that, as there needs to be a certain cadence (a few pedal cycles) established before the knock emerges. Stopping pedaling breaks the rhythm.
"does noise go away while out of the saddle" - Nope, the noise is still there even if I stand while pedaling.
UPDATE: So I just got back from the shop. He tried a different freewheel because mine had some play. That didn't fix it. He then concluded that it was the rear wheel's hub. He said on these cheap bikes they compress the hub too much and this can result in the ball bearings within making sounds. Unfortunately, he did not have a matching wheel on hand which we could use to verify. Side note: After I left the shop, I went to where I originally bought the bike and they had two other of the exact same model still for sale. I took them both for a ride and whaddya know- they both have the same exact issue. So, stay away from the Hyper Spinfit.