Bought a MTB

[Trekblur456]

What’s up guys and girls! I got a problem I thought I might be able to find some help for. I bought a bike, test ride it and took it home to go through a little more. Upon further inspection I found that the chain was completely shot using a chain checker. So I replaced it. Eight cogs So eight speed scram chain pc-850. I did test ride the bike for a short time and despite the worn chain it rode well. I put the chain on and went to give it a more thorough check today and as soon as I put pressure to the pedals what seem to me to be the bottom bracket began skipping! Do I need a new bottom bracket? Or is it that for some reason the new chain isnt correct? The teeth in the cogs and crank are mint. I looked closely while the skipping was happening and saw that it wasn’t the chain and it apperwared to actually be the bottom bracket. To explain, there is a slight skip during revolutions maybe 3-5 per. Can anybody Validate that it is the bb? Thx in advance!

[mentalboy]

Welcome to BCF, the UK's largest motorcycle forum.

Luckily for you, we're an all inclusive bunch and even luckier we have a keen pedal pusher representation so you might be in luck with your question but not from me.

Edit: Ooh, another Floridaman.
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Make mine a Corona.

[Easy-X]

The only thing that should happen with a bottom bracket is the bearings go. If you take the chain and cranks off you'd grab the axle then find some serious play or maybe even some clicking and clanking if really shot.

I say "should" as I have a feeling something else is going on
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[ThunderGuts]

The bicycle frame functions like a listening stick, which is unhelpful as it means noises can appear to come from nowhere near where they're actually coming from. BB wouldn't cause a loss/skipping drive, BB failures usually are clunking or if they're really shot grating and/or wobbly cranks. There's not much to a bike's drive system, my guess is the freehub pawls might be gummed up and sticking, so not always consistently engaging with the teeth on the hub. With a few basic tools quite easy to look at, take the wheel out, cassette off (you'll probably need a tool for this, or take it to a bike shop and get them to whip it off for you while you wait as it'll only take moments) then carefully undo the retaining bolt (often an allen-head through the centre of the hub) to remove the freehub body. Take a look at the pawls; they should have the lightest film of oil (not grease) on them and the teeth should be clean. On an old bike, especially if it's been ham-fisted by someone (sticky pawls - pour grease in there and make it worse) or if the bearings have overfilled with grease and have squirted some into the freehub body, I wouldn't be surprised to find it a mess in there. If it is, clean it up thoroughly (use a solvent like petrol but be careful not to splash the bearings as you'll wash the grease out of them too) then give a SLIGHT oiling with a light oil like 3 in 1. Pop it back together and see how it is. It all sounds quite involved but if you've got the tools, the above takes about 10 minutes from start to finish.

While you're fixing your MTB, do your CBT and get a motorbike to ride around on in the meantime.
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TG.

[Copycat73]

new chain + old sprockets = fucked new chain .. replace the old sprocket set ..
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Whatever I post I have no citation and no intention of providing one..
caveat emptor

[mentalboy]