Non-Ebike Bike help needed - deraileur help

[Ch00paKabrA]

When my nephew was here we put together some bike and went up to Mountain Creek Bike Park in Vernin, NJ. We had a great time. the bike I put together for myself is a Gary Fisher King Fisher 1. It has none of the original parts on it becasue I just bought the frame. I bought a brand new SRAM X5 8 speed Shifter, 8 speed cassette, SRAM X4 deraileur, and a SRAM 8/9 speed chain. It took me a while but I got it shifting smoothly.

The problem is that in gears 6, 7, and 8 the chain skips off of the cogs when I put any kind of force into pedaling. So, I cannot stand and pedal because it skips too much. Everything is brand new. On the front I have Raceface hollow tech cranks and a Race Face 36 tooth Sprocket. Only the one sprocket and it is new.

The deraileur is a long cage. I tried taking a couple of links out of the chain to possibly increase tension but it did nothing.

What am I doing wrong? how do I fix this.

I know Chalo is or was a bike mechanic, anyone who has some input, would be appreciated.

I took up trail riding to keep from packing on too many pounds in the off season and the fork I bought for another bike had a gouge in it so I am stuck trying to ride this heavy beast for a while.

Thanks in advance.
Cal

 

[amberwolf]

Have you tried setting it up the way Sheldon Brown's site says?
http://sheldonbrown.com/derailer-adjustment.html
that usually works for me.


When it doesn't, it usually ends up being a problem wiht chain alignment between front and rear, where the front chainring is too far left or right of the rear sprocket I'm haivng the troulbe with.

 

[Ch00paKabrA]

I hadn't read his blog on it but that is how I set it up. He does mention skipping but then refers you to his post about older worn out chains. My chain is brand new with one day of light sissy-boy slow DH riding and 2 days at the local state park with single track trails.

I will try putting a spacer on the drive side of the bottom bracket to see if moving the front sprocket over does anything. Thanks for the advice.

 

[dogman dan]

This is weird, when I have had the problem, it's been a combination of pedaling too hard on a large front sprocket, and an obviously worn rear freewheel, The 14 t gear on it, and combined possibly with stretched chain.

But you have all new stuff, I've only seen something like it with very slack chain. Tiny gear up front very misaligned with the smallest one in back. That's a gear I consider unusable, and not needed since a middle gear on both front and back will be a similar ratio.

36 tooth is medium small, I'd take more links out of the chain, till it's very tight on the larger rear gear if it's not already. And that spacer suggestion makes sense if the single gear is very far inboard. Get it straighter line up when in the smallest rear cog.

 

[Ykick]

What does the chainline look like while in the problem gears?

Sheldon Brown is classic goto site but Youtube has evolved into the place I view/learn brand specific adjustments such as Sram, etc.

This is just a drop in the bucket:

[youtube]ZTOyxOPHoGc[/youtube]

 

[Ch00paKabrA]

Thanks for the video ykick. I checked out the chain lines in 2nd and 7th. IN 2nd, when it does not skip, the chain is is far off center (to be expected) and in 7th, when it skips like crazy, the chain line is perfectly strait. I don't think adding a spacer will do anything.

Here is the chain line in 2nd:

View attachment 1

and here is the chain line in 7th:



I guess it is off to the local bike shop.

 

[Ykick]

I remember reading about idler wheel cages easily bent out of shape which may result in this behavior. One of your photos does seem to show a funny angle to the idler wheel cage? Good luck and 'hope to hear about the resolution!