Gear Confusion

[Stoned]

Hi all, I met a friend for kopi last night and we were discussing about a problem he was facing with his bike.

 

What he's experiencing is that the bike experiences a loss of power in 5th gear. He is actually able to reach a higher top speed in 4th gear than 5th.

 

After much discussion, the only conclusion we came to is that the 5th gear sprocket could be worn out.

 

He'll probably see the mech soon but I'm also personally curious as to what could cause this problem. It's the first time I've heard of such an issue. Has anyone heard of such an issue before?

[mbike508]

Sound like clutch slip. Is the rpm almost the same with 4th and 5th gear?

[Stoned]

Yea, the rpm is similar, just that the rpm increasing doesn't translate into power.

 

So this means... the clutch is slipping? But if that's the case, wouldn't clutch slippage occur for all gears and not just in 5th gear?

 

I tried his bike myself, really quite strange. It performs really nicely at lower gears, but once it hits high rpm in 5th it just doesn't respond much to the throttle. It cruises alright at 110-120 or so but opening up the throttle doesn't seem to have much effect. You can then downshift to make it fly.

 

I don't quite understand it myself. At least it still commutes alright.