MTB – Fixed?!

I sure hope so, it’s been driving me mad!

After replacing the chain, cassette and chainrings and then crashing, bending the rear mech hanger and getting a horrible slip in the gears I needed yet another fix. Straightening the hanger and trying a mech adjustment seemed to work but the slip soon came back and worse than ever. I tried another alignment but nothing seemed to work so I ended up ordering a new SRAM X7 rear dérailleur.

I picked it up this morning.

It’s a pretty easy job to swap over to be honest. The “awkward” part (for me anyway) is getting the gearing adjusted so it’s spot on. The replacement is pretty much as follows:

Split the chain and free it from the rear mech. The SRAM PowerLinks make this so easy. Push the links together and it comes right apart.

Remove the gear cable.

And undo one (5mm I think) hex head bolt and that’s it. The old one is off and the new one refits in the reverse of that.

The trick is then getting the “hi” and “lo” settings adjusted, the correct cable tension and the right hanger setting. This really got to me today but I think I cracked it in the end. The first thing I actually did was set the right “height” (?) for the rear mech. One 3mm hex head bolt lifts or lowers the whole mech. The SRAM instructions said the mech should sit roughly 6mm under the largest cog (lowest gear) of the rear cassette. So fitting the chain to that cog, winding the screw in (or out) and that’s one job done.

Then it came to the “hi” and “lo” adjustment and fitting the gear cable. It’s a simple procedure but I always manage to get myself in one of those “fuck this shit” moods. It should be just as simple as:

Fit the chain to the smallest cassette cog (highest gear), and select that gear with the shifter.
Wind the “Hi” screw in or out until the jockey wheels of the mech sit in line with the outside edge of that cog.
Fit the gear cable with a nice amount of tension.
Spin the pedals and switch down to the largest cog (lowest gear) and adjust the “Lo” setting so the jockey wheels sit directly under that cog.

Simple

Except I couldn’t get it right. I normally do all my adjustment with the bikes the right way up and just look from the back to check the alignment. Most of the time it works but this time I just couldn’t hit the sweet spot. Sure on a test ride the gears all worked but in 6th and 7th the chain would consistently slip and try to get into the next gear.

The “fuck this shit” mood was well approaching after a couple more adjustments and no success but then I had a quick thought. I flipped the bike over and spun the pedals to see if I could witness the chain slip…and I did. I could see it catching on the next gear and lifting up ever so slightly, and all because the rear mech was too far over. After changing to the highest gear I could see instead of the jockey wheels being in line with the OUTSIDE edge of the gear they were actually lined up with the INSIDE edge. Obviously checking the alignment from the rear didn’t work so I made one more adjustment, this time with the bike upside down and what do you know…. it worked!

Well, I’ll go for a proper ride during the week and check for sure but on the test ride every gear selected perfectly and there was no slipping. I think it’s almost safe to say next weekend I can head back over to Cannock for another round!

Happy days!

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