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iamthetas 07-28-04 06:38 PM

chain question
 
my chain keeps falling from the mid front sprocket to the small one when I am doing serious bumpage but not pedaling. has anyone else had this problem and how did you solve it? it does fine when pedaling it just seems to slip when it is slack and I hit big bumps,jumps,roots etc. it is painful to think I am in one gear going downhill and finding out Im in a much smaller one when I start to pedal again. its a Shimono XT crank,sprocket and Im not sure what Shimono chain.Ive had the chain checked and it is not stretched out of specs. can a weak spring on the rear der. cause this? thanks for the help.

FoX Rider 07-28-04 06:52 PM

Two words: Chain Guide.

iamthetas 07-28-04 06:54 PM

is that the "rollamajig" thing or is it something else? thanks again

FoX Rider 07-28-04 06:56 PM

For others posting. I'm looking for a chain guide for my Haro. I have 2 ring +bashgaurd setup. Whats a good chain guide?


This is a chain guide.

(The white roller on the bottom left and white thing on top)

http://www.pricepoint.com/images/sty...5%20BLADS4.jpg

iamthetas 07-28-04 06:58 PM

ok thanks

FoX Rider 07-28-04 06:59 PM

No problem, I have this problem a lot. Thats why I'm investing in one. The problem; A decent one empty's your pocket. Ex. $100+ (Mostly me and my poor friends :))

iamthetas 07-28-04 07:13 PM

I went to JensonUSA and saw some for under $100 but I do not know whats good and whats not.thanks again

Hopper 07-29-04 02:53 AM

Possible the best ones are Evil. However that's only what I hear, I have never used one. But my Aireal is really good, basically the same as the Blacksire. And MRP are also a big name in chain devices. All of these have bash plates on them thogh.

If you don't want a bash plate, try a truvativ chain device, there meant to be good. Just look around, try mtbr.com.

FoX have fun looking for a good one :) mine bloody cost me about $90 US and then another $40 US to fit it, because Bighit's don't have ISCG mounts, and the device had to be anglegrinded carefully to fit, and I didn't trust myself doing it.

Cornish_Rdr_UK 07-29-04 05:24 AM

The avid Rollamajik is designed to minimize that pain in the ass cable that shoots off at that stupid angle from your rear derailler, sposed to really help, going and buying one now :D

FoX Rider 07-29-04 09:04 AM

I'm looking at Evil. They do have the best chain guides. I already have a bashgaurd so I'm looking for just a chain guide. But if I must, i'll replace th chain guide.

iamthetas 07-29-04 07:14 PM

I was thinking of getting a rollamajig due to a reputation for making shifting smoother. I am happy with the way my gears shift but good to better is a good thing ,especially for around $10. I was wondering if the springs in the rear der. can get weak and let the chain flop. my wife is ok with my getting new tires but I think she'd kill me if I got a chain guide at this time. oh well Christmas is coming!HO HO HO.thanks for all the help folks

Dannihilator 07-29-04 07:22 PM

Well, you don't get that dreaded cable loop with Sram's X series deraillieur.

Also if you are doing xc a chainguide is stupid. The chain rings and chain are probably worn or the front deraillieur is out of adjustment.

iamthetas 07-29-04 08:04 PM

front der. out of adjustment? please elaborate. I do not have x series but I do have 7.0 . I have no loop either. I understood it helped smooth shifting. I was not aware of any cable loop relief. my chain rings are fine and I have gauged my chain and it is well within the specs. thanks again

Dannihilator 07-29-04 08:42 PM

Front deraillieur is out of adjustment as being the cage is pushing the chain off the middle cog and into the small cog. Also are you pedalling through the bumps if you are, you're causing it to do that. Coast over the bumps and see if it works out better. If not, the deraillieur need adjustment.

Cornish_Rdr_UK 07-30-04 04:03 AM

Iamthetas, i just bought an avid Rollamajik, and it didnt come with any instructions, so im trying to find out how to put it on, if anyone has any suggestions, GREATLY appreciated

a2psyklnut 07-30-04 07:36 AM


Originally Posted by iamthetas
my chain keeps falling from the mid front sprocket to the small one when I am doing serious bumpage but not pedaling. has anyone else had this problem and how did you solve it? it does fine when pedaling it just seems to slip when it is slack and I hit big bumps,jumps,roots etc. it is painful to think I am in one gear going downhill and finding out Im in a much smaller one when I start to pedal again. its a Shimono XT crank,sprocket and Im not sure what Shimono chain.Ive had the chain checked and it is not stretched out of specs. can a weak spring on the rear der. cause this? thanks for the help.

Kona was right and your front derailleur is out of adjustment.

Here's how to adjust it and minimize the problem.

What the end goal here is to center the front derailleur over the middle chainring.

Shift into the middle chainring(front) and into your largest cog(back). Then using the barrel adjuster at the shifter, turn it out (counter clock wise) until the chain starts to scrape the inside plate of the front derailleur. Then turn it back in 1/2 turn (or until the scraping stops). Then shift into the small cog in the back. Check to make sure the chain doesn't scrape the outside plate. If it does, turn the barrel adjuster back out. Go back and forth finding a "happy compromise" between the big and the small cogs and the chain scraping.

If the chain still drops, you may want to consider letting the chain scrape the inside plate when in the big cog. (This will mean keeping the front derailleur over to the outside).

L8R,
Have a good ride this weekend, I'm heading out on Sunday with a crew!

BigHit-Maniac 07-30-04 07:58 AM

Also... you may want to consider taking one or two links out of your chain. Excessive flop in a too-long chain will cause it to jump all over your rings.......

iamthetas 07-30-04 07:05 PM

it does fine as long as Im pedaling over bumps. it comes down when I coast over obstacles. I have had trouble with the thing for a while now and am just getting it to work on all 3 rings.I will try the movement that as suggested again as you said. what is the right height also?the initial problem was it was too hi on the frame but I am not sure if I got the right height this time. this advice is soo cool thanks alot.this thing has me stumped.

a2psyklnut 07-31-04 12:36 AM

The first thing you do when adjusting a front derailleur is set the height. You want to set it to where there is only a 1-3mm gap between the big chainring and the outside plate of the front derailleur. An easy way to measure this is to place a penny on the teeth of the big ring and set the derailleur height to where it touches the penny. Wa La (Viola)!

Second is to look down at the outside plate from above. Looking straight DOWN from above. You want to line up the outside plate so it's parrallel with the big chainring. Then check the height again and then tighten the clamping bolt.

Turn your barrel adjuster at the shifter all the way in then back it out one full turn. Tighten the cable. And then do the steps I wrote above about centering the front derailleur.

L8R

iamthetas 07-31-04 08:45 PM

will do.it was on center but when I did the height it was more than 3 mm.I know this from memory and will set it tomorrow.I also noticed a lot of "flop" in the chain and if I peddle the least bit back it falls to the lower gear from the bottom up so I will have my chain checked again too. if its in specs still I will take out a couple of links.I do not have a chain guage but know a LBS owner who will do it for me again.( I hate asking for help on such a simple problem so thanks for all the help again).someone once posted a link to an owners repair guide that could be downloaded when I asked about disc brakes but I do not have the link anymore and my son reburned the disc I made. does anyone remember the link?it was awesome

a2psyklnut 08-01-04 05:10 PM

at The Bicycle Mechanics thread you can download all of the chapters of Barnett's Bicycle Repair. Very Good and FREE!

I also like www.parktool.com

L8R

iamthetas 08-05-04 06:09 PM

got it set as instructed but the problem persists. bummer.thanks for the links


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