JeffOYB

I just got a cheap used Schwinn hybrid cruiser type bike. I'm going to dig into the rear hub first because of this issue, but I thought I'd ask for ideas here.

In my test riding I'm thinking the bike is making me work harder than I should be. I also notice two things, which might be related:

When I pedal hard I get a clunking clunking sound. Not sure where it's coming from. The bike has cheap 1-piece crank.

When I coast I feel a pulsing resistance -- which must be coming from the rear hub.

Both wheels spin freely.

I've had the 'clunk clunk' in a bike before but not in the last 10 yrs, etc., and I don't recall the cause/fix.

[UPDATE: It's a 6/7 spd derailler bike with caliper brakes.]

WizardOfBoz

I concur with your rear hub hypothesis. Could be bearings, or a bent or broken axle. One key question: is the pulsing synched with the wheel rotation? If you find an isolated safe place and coast, does the pulse synch up with the inflation stem or a wheel decal or something to indicate wheel rotation?

What kind of gearing/brakes do you have? I guess if this is a coaster brake model it could be that the brake is morked up.

79pmooney

Is this a derailleur bike or an internally geared hub? My first thought was a freewheel or freehub issue but if it is an internally geared hub, that could also be the issue.

JeffOYB

Thanks. I updated the OP with the helpful info. It's a caliper bike with a rear derailler and 6/7 speed freewheel/cassette

Bill Kapaun

Remove the rear wheel and-
Rotate axle. Feel for roughness/sloppiness.
Ditto Free wheel.
Not sure why you haven't done something that simple yet. You have the bike.

JeffOYB

Sorry for any confusion. I'm asking what people think BEFORE I get into the bike. That's all. It's possible there's a common known cause for clunking and pulsing. I've had it happen before but as i said i forget what it was. But yeah i'm getting into it today. we'll see!

JeffOYB

well, i was out of town, visiting relatives. i checked out the rear hub. zero play, maybe a touch tight. I loosened the cones a smidge using tools from their garage. no bike tools available. not sure much improvement. i wasn't going to repack or anything. still, i wonder what is the common cause of clunk-clunk from rear hub under load. whups, i forgot to spin the freewheel or try to feel how that was behaving.

thankfully this is a utility bike that's only going to be used short distance on flat ground. it only clunked for me when straining hard up a hill.

i also felt some minor pulsing resistance from the front wheel when coasting.

i suppose both hubs need repacking?

well, i've left now. if the owner ever notices they can take it to a LBS and good luck to em! ... : )

Wilfred Laurier

Pulsing resistance is also commonly caused by brakes rubbing a rim that is out of true. It could also be caused by the tire hitting the frame.

The clunk is quit likely the bearings in the bottom bracket. One piece BBs are easily serviceable with regular hand tools.

JeffOYB

no brake strike

it's an internal resistance

as i posted i get a clunk clunk when pedaling hard then a pulse pulse when coasting -- which made me think maybe not in crank. but it could be. i never did check for tightness looseness grabbiness of crank -- rats. could've done that easily. oh well!