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Crunching/grinding in bottom bracket area (only when muddy)

Buns_of_SteelBuns_of_Steel Posts: 20
edited April 2014 in MTB workshop & tech
I've recently decided to get back into mountain biking again after a ten year absence so times have changed some what since my last exposure to the cycling world and even then i was only a social cycler who did a bit of tinkering here and there so please forgive my lack of knowledge and any silly questions.

So i bought a Scott Genius 720 four weeks ago and have ridden 40 miles tops on it 30% of which is through woodland trails, the rest on the road and public bridleways, gravel paths etc. Nothing too exciting but I have found a recurring problem in my last few rides. I clean and oil my bike after every ride and when i ride on the road of clean paths it rides absolutely fine but one ride i was cycling through alot very thick clay mud and once the bottom bracket area got covered in mud i got a nasty crunching/grinding sound. I could feel it in the pedals as well. I got home and hosed the bike down, scrubbed the drive train clean, oiled the chain and rear mech. I then went out on a 5 mile ride mainly using roads and footpaths and it rode like a dream. Then i went out on a few local trails and once again as soon as the bottom bracket area got muddy the nasty crunching/grinding came back. Got home cleaned and oiled the bike and it was fine.

I've inspected the components as much as i can but honestly im not entirely sure what im looking for. The cranks have no movement in them when i physically push/pull them. The components look brand new with no bangs or dents. Nothing looks bent. I use Muc-Off C3 Dry Ceramic Lube in dry conditions, Weldtite TF2 Performance Lube With Teflon when the weather turns which recently has been all the time. I've just bought some Finish Line Wet Lube to see if that helps things.

I honestly have no idea what could be causing this issue. Like i say its fine in dry clean conditions but horrible in muddy wet conditions. My first thought was maybe its dirt and grit getting into the bottom bracket/crank area but the bottom bracket has sealed cups which supposedly keep dirt and water out so for a £3000 bike with 40 miles on the clock i cant believe its normal to experience that. The only time i experienced something similar was when the bearings went in my bottom bracket on my old bike but this rides so nicely when its clean it cant be that can it? I've got a 2 month service in a few weeks so i'll bring it up then but in the mean time if anyone has any suggestions

Here is a link to my bike with a spec list ... 4A3C065E2D

Any similar experience or ideas are more than welcome.

Any extra info wanted then please ask.



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