MTB Sram BB Service

[love2fly]

Hi there

 

The cranks on my MTB have developed a serious amount of play, quite suddenly and without any warning noise on this morning's ride.

 

If I tackle this myself am I going to need any additional cycling specific tools such as bearing extractor (have a BB tool (Parktool BB but its for my roadbike - 43mm?)) and a big variety of general tools like allen keys etc?

 

May be difficult to tell but is it likely just bearings or is it likley the BB is trashed?

 

Cheers

[David Marshall]

Those BB's are usually replaced.  Yours is a Sram GXP BB.  They come in MTB and road versions.  That said you can get Enduro bearing kits with seals to replace the bearings in the cups, which slightly reduces the cost.  

 

To remove that crank you loosen the bolt in the non drive side.  That is the SMALLER of the two heads (with a 8 or 10mm allan key).  The bolt will loosen and then feel tight again as it presses against the larger cap bolt before pushing off the left crank arm.  Remove the chain from the chain rings and tap out the right side crank arm with a rubber mallet.  There may be an array of washers and a spring washer on the crank axle.  Just note the position and side of the frame that they are situated on so that you can fit the new ones in the right order.  Use the same tool to remove the BB cups that you use for Shimano external BB's.  Usually you get instructions in the box with the BB or you can get online.