bicycle chain/gear question

Post by **[xeno]Julios** » Sat Jun 18, 2005 6:49 pm

Ok - so I'm trying to understand how chains and transmission works - got a long journey of learning ahead.

Eventually I'll find a good bicycle forum to discuss these issues, but could use a beginner's helping hand right now.

My gears shift pretty smoothly, but when I'm in highest gear (biggest chainwheel/smallest sprocket), and i'm going really fast, I hear a rattling on the chain when i'm on my downstroke with the right pedal.

The chain doesn't skip, but it feels like it *might* skip. I'm wondering what might be causing this.

Also, when I'm doing bicycle maintenance, is it ok to just put the bike upside down resting on seat and handlebars?

Post by **l0g1c** » Sat Jun 18, 2005 6:55 pm

When I'm in my highest (fastest) gear, my derailleur rides right on top of the back gear and is a little noisier than the rest of them. Not sure if this is the case for you, but it's perfectly normal.

Putting the bike upside down is fine as long you're not crushing/pinching any cables. In fact, this would be a great way to check if the above derailleur thing is happening, or if it's in need of fine tuning.

Post by **Foo** » Sat Jun 18, 2005 6:58 pm

the rattling is probably due to the alignment between your front chainrings and the sprocket on the back. Depending on the gear you're in, the chain sits at different angles between these 2 points.

However, in highest gear, your chain should be pretty much straight (as it's as far to the left on both chainring & sprocket as it should be).

What might be causing the problem, then, is the 'stop' adjuster on either the front or rear derailleur. They have 2 screws mounted in them which controls the furthest extents to which they'll move left/right. By adjusting these screws, you may be able to line the chain up better on the bottom/top gears.

As for bike maintenance: yeah it's fine. Depends on the type of bike (road bikes can't really be turned over like that as the handlebars don't touch down right) and the kind of saddle (you might rip it)

Post by **[xeno]Julios** » Sat Jun 18, 2005 7:03 pm

arg - i just turned my bike upside down to examine it, and found out that the back rim is slightly bent. It rubs against the brakes during portions of the rotation.

Trying to learn how to "true the wheel"

Post by **l0g1c** » Sat Jun 18, 2005 7:06 pm

And also, make sure you're shifting properly and not crosschaining. I tried to type it out, but there's probably better stuff on the 'net about shifting patterns. I'll look more when I get home.

Post by **l0g1c** » Sat Jun 18, 2005 7:08 pm

[xeno]Julios wrote:arg - i just turned my bike upside down to examine it, and found out that the back rim is slightly bent. It rubs against the brakes during portions of the rotation.

Trying to learn how to "true the wheel"

Ooh, that's easy.

Step 1) Take bike to shop.
Step 2) Pick up bike and pay the nice man.

:icon25:

Post by **Foo** » Sat Jun 18, 2005 7:09 pm

Yeah, wheel trueing is really, really hard shit. And a big time-waster.

Starting attempts WILL end with a flat-spotted wheel.

Post by **Zyte -_-** » Sat Jun 18, 2005 7:22 pm

lol coincidence. i cannot figure out what i should do: running or biking.

I like biking cause of the concentration that you need, the speed and focus when going downhill and keep yourself from smashing your head, keeping your eyes wide open and on the road, and learn how to master your bike the best.

On the other hand, it feels like running adds more to my shape, and i love to just run for half an hour surrounded by nothing but nature. Getting a good rythm etc. Its kinda peaceful i guess :]

Anyways, i have a problem with my bike atm. About 4-5 days ago my chain started - i guess its called so - 'skipping'. When i put a lot of pressure, for example when im standing on the pedals (which i try no to do much), the chain 'shoots' of the chainweel onto another one, like there's not enough grip. It's hard to see what actually happens cause i have my eyes on the track..
I have for the rest no problems shifting, which goes all fine. Its just when i put a lot of pressure on the pedals. This does not happen with the biggest chainweel.

Post by **Foo** » Sat Jun 18, 2005 7:30 pm

That's usually a dirty chain/cogs. If a decent clean and regrease doesn't fix it, then you might need to tweak your rear derailleur settings.

Post by **rep** » Sat Jun 18, 2005 8:24 pm

Regular maintenance prevents problems. It goes beyond washing the bike, you have to check it after every few rides. If you're planning on taking it to a mountain, you'd better check everything before you go.

Post by **SOAPboy** » Sat Jun 18, 2005 8:27 pm

[xeno]Julios wrote:arg - i just turned my bike upside down to examine it, and found out that the back rim is slightly bent. It rubs against the brakes during portions of the rotation.

Trying to learn how to "true the wheel"

adjusting spokes is cake.. ^_^

grab a wrench and get to it..

Post by **l0g1c** » Sat Jun 18, 2005 8:32 pm

Here's a good read for those shifting patterns I was talking about.

Post by **rep** » Sat Jun 18, 2005 8:59 pm

I like the last part of that article.

"Remember, it's always best to keep your bike in the optimal gears, those with the highest numbers. That way, you'll always go fast."

:lol:

Post by **l0g1c** » Sat Jun 18, 2005 9:21 pm

Slow down, speed-reader! Your comprehension is suffering something fierce. :icon22:

I do think he should've blacked out some of the gear combinations you shouldn't use in the graphs at the bottom, though.

Post by **Timbo** » Sat Jun 18, 2005 9:25 pm

The thing about out of true rims is that the worse they are, the easier it is for the rim to be knocked further out of true. So it pays to keep it tight. (I've built about 10 wheels from scratch.)

As for the rattling, perhaps your chain is a little long? If the rear mech isn't tensioning the chain properly in this gear maybe this is the problem. The usual reason for skipping (which you don't have right?), is simply wear on the sprokets/chainrings. Check to see if they appear "sharktoothed".

It's hard to diagnose rattling/knocking things remotely.

Post by **rep** » Sat Jun 18, 2005 9:38 pm

l0g1c wrote:Slow down, speed-reader! Your comprehension is suffering something fierce. :icon22:

I do think he should've blacked out some of the gear combinations you shouldn't use in the graphs at the bottom, though.

Weak attempt at a flame since you knew I was joking.

Minus 10 points, l0g1c... Hell, minus another 10 for that s00p3R k3wL n4m3. :icon29:

Post by **l0g1c** » Sat Jun 18, 2005 9:45 pm

Nobody is flaming you (well, I'm not, anways). I only assumed you went past the last part of the article too fast. I do like the nickname flame, though.

Post by **[xeno]Julios** » Sat Jun 18, 2005 9:54 pm

Timbo wrote:The thing about out of true rims is that the worse they are, the easier it is for the rim to be knocked further out of true. So it pays to keep it tight. (I've built about 10 wheels from scratch.)

As for the rattling, perhaps your chain is a little long? If the rear mech isn't tensioning the chain properly in this gear maybe this is the problem. The usual reason for skipping (which you don't have right?), is simply wear on the sprokets/chainrings. Check to see if they appear "sharktoothed".

It's hard to diagnose rattling/knocking things remotely.

tx timbo - the bicycle dude is gonna have a look tomorrow - and he'll true up the wheel too.