geoffstanley

Hi everyone!

I've read tons of threads on BikeForums.net in the past, and have so far always found something posted previously that answers my questions. But this time I think I need to explain myself to a human, not a search engine! So here's my first post!

I have a Surly Long Haul Trucker, and it went on a 5500km tour when it was born. The next summer I swapped out the cassette, and then, if memory serves, I had to wait a little while (maybe 100 - 200km) before I managed to get the chain and swap that over as well. So for a bit there I was running a new cassette on a very old chain. I then put a new chain on. That was last summer.

Now, I'm gearing up for another tour, down the west coast! But I get this strange feeling from the drivetrain. When I put it under a good load, it feels like it's "humming", and I feel it through my feet. It's hard to describe. It doesn't make any noise, but the feeling is there. It just happens in the part of the pedal stroke where I'm putting most of my force through the drivetrain. It also seems to happen only when I'm putting that large force through my right (driveside) foot. (Maybe it happens when I put a large force through my left foot but I don't feel it on the driveside because my right foot isn't pressed down, making good contact with the pedal.) I will check this fact, but in the meantime I wanted to put this up to see if anyone has ideas! One other thing is that it only seems to happen in the large chainring (there are three on this bike). Even in the smallest (fewest teeth) cog at the back, and the middle chainring where I can still put significant force through, I don't feel it when in the middle chainring.

Could it be the BB? This bike has seen some rain, though I try to clean it with a rag. BB has never been overhauled.

Could it be the cassette, which wore into the old chain before getting a new chain?

Could it be something really simple, like torquing down a stack bolt or the pedals or the crank fixing bolts?

Could it be the chainring, worn down?

Shimano Deore XT RD
Shimano Tiagra FD


Thanks in advance for whatever ideas you guys and gals come up with!
geoff

Re-Cycle

Sounds like the drive train is not skipping under heavy loads so I'm going to guess that the bit you ran the new chain on the old cassette did no real damage.

You should pull off the crank arms and spin the bottom bracket spindle in your fingers to see if that is your problem. You will figure out quite quickly what it's condition is.

Ira B

From your description I suspect a worn or under lubed chain.
Try lubing the chain. If you notice any difference at all this should narrow it down to the chain, chainrings or cogs.

geoffstanley

Thanks for the replies!
I lubed the chain up and now it seems to be a whole lot better. I still notice it, very very slightly, under a ton of pedal pressure, but it's completely tolerable now. I'll have to do better at keeping the chain well lubed. Yesterday is when I was really noticing it, and the chain was definitely dry yesterday when I picked my bike up from storage...!
I'll rest easy knowing that lubing the chain was both suggested as a culprit and seemed to do the trick.
Though now I feel like a bit of a noob...!
Ira B, do you have any follow-up thoughts? Chain, chainrings, or cogs?
Thanks to you both!

gyozadude

If you sense humming in the big ring, check the wrap of the rear derailleur, and also check chain length. If the wrap is too much, the top RD pulley cog might be kissing the FW/FH cog through the chain and causing that humming. Also, if you replaced the cassette and increased the top size of the cog, you may need to extend the amount of chain by a few links. Too little chain and that puts more tension on the RDR which wraps more and causes the buzz. There are also different lengths of RDR arms. Longer arm RDRs can pick up more chain. If buzzing is greater during cross-chaining, then that's possible sign.