Bicycle Mechanics - Still having trouble with gear grinding

Help ! I have had to take my Brodie back to the store three times for this problem and it continues to reoccur.

Basically, I have two rings. In the 15th and 16th gear...they will suddenly start to grind.
It appears that the chain might be rubbing against the derailler or something. I don't know but when I am cycling and change into these gears, the chain will grind constantly until I shift down to a lower gear.

The bike shop basically told me that it is the gear cables stretching but I have had the bike 2 months now and why it only these two gears that are causing a problem.

Any suggestions ?

Justen

If the bike shop can't fix it, demand a refund. They sound like a bunch of morons, anyway.

Alex is right - find another bike shop.

My guess is that the chain is rubbing against the outside of the front derailler cage. You should be able to see this by looking down at the chainwheel while the noise is happening. To fix this tighten the front cable adjuster to counteract cable stretch, and/or unscrew the H limit adjuster 1/4 turn.

make sure the deraileur is installed properly(aligned properly)..

Correct me if I'm wrong, but I recall reading that some front deraileurs are designed to be used on 52T+(outside ring) and ATB der. are designed to be used on 48T-.

Also, some derialuers are designed for narrower chains. Using wider chains with these derailuers; I can assure you there would be rubbing..

Justen,
Let's get some data. You say you have two chainrings. What size? How many cogs in back? 8 or 9? When you say 15th and 16th gears do you mean big chainring, smallest and second smallest cog? You say the bike is 2 months old. How many miles do you think you have ridden on it?
Regards,
Raymond

Originally posted by RainmanP
Justen,
Let's get some data. You say you have two chainrings. What size? How many cogs in back? 8 or 9? When you say 15th and 16th gears do you mean big chainring, smallest and second smallest cog? You say the bike is 2 months old. How many miles do you think you have ridden on it?
Regards,
Raymond

There are 8 cogs on the back.
I have a bashguard on this bike so only have two smaller rings. When I say 15th and 16th gear...well, I'm just figuring that I don't have my third ring so I just figured they are the highest gears on the second ring.

The bike is 2 months old. It has about
1200 kilometers (750 miles) on it.

That's all. I haven't cycled it much.

Justen

You are running a bashring and your chain grinds in the two tallest gears(smallest cogs) when in the larger front ring. And adjusting it does not fix it? That sounds like the chain is touching the bash ring, look at the edge of the bashring on the chain ring side. Is the finish getiing rubbed off? A set of chain ring spacers .5mm to 1.0mm, to space out the bash ring, will take care of that.

Originally posted by Rev.Chuck
You are running a bashring and your chain grinds in the two tallest gears(smallest cogs) when in the larger front ring. And adjusting it does not fix it? That sounds like the chain is touching the bash ring, look at the edge of the bashring on the chain ring side. Is the finish getiing rubbed off? A set of chain ring spacers .5mm to 1.0mm, to space out the bash ring, will take care of that.

Hi there,

The Bashring is very slightly nicked at the top on the side of the chain ring and is very slightly scraped about an inch down but it doesn't look like a repetitive wear pattern just a slight scrape.

Is it possible that it could be too close to the derailler - the chain ? and that is why it is always scraping on it ?

Justen

Possibly, if you have grinding and the chain is not touching the der. It has to be touching something and the bash ring is in the right spot for your set of circumstances. Both of my mountian bikes are set up with a bashring in place of the big ring and on one of them the chain touches it when in the small cog in the back, but I almost never use that gear, so it has never been an issue.

Originally posted by Rev.Chuck
Possibly, if you have grinding and the chain is not touching the der. It has to be touching something and the bash ring is in the right spot for your set of circumstances. Both of my mountian bikes are set up with a bashring in place of the big ring and on one of them the chain touches it when in the small cog in the back, but I almost never use that gear, so it has never been an issue.

Okay, I just spoke to the bike mechanic at this LBS. He thought it was the bashguard to from what I explained and said it was nothing to do with the gear cables stretching like the other two guys at the bike shop had suggested.

They are going to put spacers on it to stop the chain from rubbing on the bashguard if that is the problem.

Since this problem has existed since I got the bike, they said they will probably do it free of charge but he wasn't sure as he has to check with the owner.

Justen