recklesscogniti

Unfortunately I have no bike shops here that speak English or know how to fix anything that isn't a kid's bike. I was hoping someone could wade through my vague problem descriptions and help me out.

Anyway, when I am on the 2nd and 3rd chainrings (middle and smallest) and am set up on the 3 highest gears, I get a weird shaky/mushy feeling on the down pedal when I pedal hard. There really isn't a sound, no squeaking or anything, and i have not ridden in anything but sunshine thus far. I don't have many miles on the bike and I am not exactly trained in bike mechanics.

Upon inspecting the chainrings, it looks like the chain might be rubbing up against the inner-side of the bigger ring, is that possible? If so, is there a fix for that?

Thanks

staehpj1

There could be a chain line issue, but if this is a stock LHT complete I doubt it. If you swapped cranks, maybe. If that is the problem a different BB may be in order. https://www.sheldonbrown.com/chainline.html

In practice you really shouldn't be on the small ring and the smallest 2 or 3 cogs.

Oh and make sure your crank arms are not loose.

joninkrakow

If it feels mushing without sound, I doubt that the rubbing is at fault. As to the rubbing, when you are in the bottom front chainring, you shouldn't use the smallest 3 or 4 gears in the back (one past the halfway point, I would surmise would be safe). Also, when in the largest chainring up front, you ought not use the largest gears in the back--same rule of thumb. In both cases, you are forcing the chain through extreme angles, and will get the rubbing problem, and increased wear.

Now, as to why you would get rubbing in the middle chainring.... hm.... I suppose it's possible that something is out of alignment, but not seeing it, it's impossible to tell, and I can't figure what could be out, other than maybe the adjustment for index shifting for the front derailleur. Do you have the option to do friction shifting? If you use that, does it help?

-Jon

Bacciagalupe

I recommend you take this to the Bicycle Mechanics subforum. There's nothing special about the LHT gearing compared to any other triple....

nubcake

id probably start by checking to make sure the crank bolts are tight, along with the chainring bolts. the chain being at such an angle could cause it to sideload the chainrings a bit and cause things that wouldnt come up with a straighter chain line

treebound 

+1 on checking the chainring bolts and bottom bracket.
And please clarify what is meant by "and am set up on the 3 highest gears", as this could mean either you are talking about the three largest gears in back (most teeth) or the three smallest gears in back (aka: high gear). I don't know if you're using "highest" as an elevation/diameter indicator or as a gear ratio indicator, I've seen and heard it used both ways by folks.

What I've told people in the shop is to only use the three largest cogs on back with the small ring on front, and the three smallest cogs on back with the big ring on front, and to not use the biggest or smallest cogs on back with the middle front ring. Cross-chaining is not good.

Check any and all bolts and assemblies on the bike for tightness or snugness. You can sort of check the bottom bracket with just your hands and pushing/pulling sideways on the pedals/cranks back and forth.

El Pelon

Probably just cross chaining as mentioned above. STay out of the extreme combos and you will be fine.

antokelly

there's load's of video help on utube ,

Longfemur

That sounds exactly like you're cross-chaining too much. Just don't use those gear combinations. Many people don't realize that most of the gear combinations they have on there overlap anyway, so there's always a better choice. Try to use the largest ring in front with the smaller cogs in back, and the smallest front ring with the larger cogs in back. The middle ring should be Ok with any of the rear cogs, but still, you want to avoid extremes and so you try to stick to the middle cogs if you can. That's why bikes have so many gears... so you have plenty of choices among the available combinations while avoiding excessive friction from the chainline. Use the small ring for going up steeper hills, but otherwise, do most of your riding in the middle ring (rings are in front, cogs in back). As you go faster, shift to smaller cogs until you start getting that chainline problem you describe. This is your signal that you are running out of gears in that ring, and so you should shift to the larger ring in front. It's not like a car transmission which just goes straight up or down.

In other words, the purpose of you having a triple on that touring bike is not really to give you 21 or 27 speeds (or whatever number you have on there). It's to give you a good, useful range of gears. But many of the possible combinations are gears you will never use.

BigAura

+ chainring bolts/bottom bracket.

As a simpler alternative possibility: be sure your skewer is sufficiently tightened, you may me getting a slight torque induced pull when pedaling hard.

recklesscogniti

Wow, thanks for the help. It sounds like I was cross-chaining too much. All the different chain terms are confusing me, but I it sounds like it. By highest gears, I meant the most difficult to pedal, require the most work. Thanks for the link to the Chainline site from Sheldon Brown, should have known about this stuff, but at least i do now. Consider this question answered. Cheers

Ronsonic 

There's extra friction and a lot of spring action in the rear der when you cross-chain. I'm thinking that's what you're feeling. If you lift the bike and pedal by hand in a variety of gear combinations you'll see and feel what I mean. The rear der takes up slack by winding the chain back and forth between spring loaded cogs, I think "mushy" is a fair description.

Hasek

It took me a little while to figure out the gear/chainring terminology. Here's how I remembered it:

"Left is low" as you're sitting on the bike, front and rear. "High is harder"... to pedal which would make the right side gears/chainring the high ones.