Mountain Biking - Stuffed up rear end

About 3 weeks after I got my Mongoose DH I was doing jumps and screwed the derailleur into my spokes, I talked about here in a rant thread I started. Anyway Today, after having my bike serviced last week, I took iy on the trails for the first time properly. Well coming down a FIREROAD I start to here a click, then bang, about 5m after a rocky sectio my rear locks up. My drailleu was through the spokes and torn to shreds.

Well I took it into the bikeshop, they are going to fix it all up for free and take the whole bike apart and look at everything to find out why my bike is destroying derailleur hangers. Apparently at another store some guy was having the exact same problem as me. They fixed this by putting a short cage road derailleur on it. So I'm getting a Tiagra road derailleur pu on it (equivelent to deore). The strange thing is I know people who put their Goose DH through hell and not have a single problem. Does anyone know what sort of difference a road derailleur will have conmpared to my not so old but rooted deore?

Run a single-speed :P

Nah, I need to be able to ride this bike up to my trails, and if I want to enter the interschools DH and 4X competition I need to have at least 3 working gears.

The shifting should be crisper......ive been pondering about running a Ultegra on mine.

Stuffed up rear end
Hmmm
http://www.ibstales.com/images/products/exlax.jpg
The shifting might be a bit crisper, but I'm curious as to why some of that model exhibt the problem while others are fine.

I thnk the tiagra is more tensioned than a standard mountain bike derialler, many trials bikes overf here use road deraillers, i think thats the reason why

The shorter cage derailleur will offer less derailleur as an offering to the spoke gods, and not be as likely to catch on the spokes. But if you have to change the derailleur to a short cage, then I would say there is something wrong with the hanger/chain stay interface. Do you dump the bike much? Even a small dump on the derailleur side can bend the hanger. And I have found some bikes to have such winpy hangers that hard shifting can tweak them. Especially after they have been straightened once or twice already.

limit screws, lad, limit screws.

yep, limit screws. On the shifter when you bring it up to first gear push the lever as far as it will go and it goes actually paste first gear for a brief moment. Ive had the problem you did, well only once, and i found it was the derailleur hanger bent slightly inward.

It wouldnt be the hanger as last time it happened it got replaced. It wouldnt be the limit screws because he just got his bike back from a service and they wouldve checked the gears.

It wouldnt be the hanger as last time it happened it got replaced. It wouldnt be the limit screws because he just got his bike back from a service and they wouldve checked the gears.
Just because the hanger was replaced, does not mean he didn't dump it again. I have customers who carry 2 extra hangers at all times. We don't have enough info to determine just what the problem is. All the suggestions are reasonable given the story provided.

Another problem I have been running into is the careless placement of the Hanger in relation to the gear cluster by the various designers. When all bikes had solid hangers, the consistent relationship to the shifting parts could be counted on. Now, with everyone using their own design on bizarre rear triangle set-ups, the hangers sometimes don't hang just where they are supposed to, even when they are new and unused. I have had to get creative with several of the newer bikes to clean up rear shifting problems. One fellow in my area had a machine shop fabricate him a hanger for his bike that dropped the derailleur 1 mm lower than the one the bike came with. That solved the b-adjustment problem we were having in Low/Low. If there is one thing I would like to see standardized, it is derailleur hangers.

Didnt you read what he said? "I took it on the trails for the first time". So he hadnt been riding it before.

No the bike hadn't been dumped or thrown on the ground. And if you think the hanger is weak, you should look at the bloody thing, it is fricken huge and they cost a hell of alot, $55 Aus

It sure is a beefy hanger. If the hanger was weak, it would have snapped instead of the derailer pulling through the threads.

Seriously, you dh, could it be you have been having some bad luck. Maybe bouncing rocks off the deraileur.

By putting a short cage deraileur, it sounds feasible. Maybe during full compression you deraileur is very close to the ground. There are other options too, poor shifting, poor chainline on the bike itself, instead of a bad deraileur maybe the rear triangle is off. The potential problems causing this are almost endless. Byt fixing the problem with a short cage deraileur, it sounds like it might be normal wear and tear for a dh bike. (I run a short now myself for the same reason)

I've been talking to the guy at the bikestore, and he used to have one of these bikes for 18 months. He had no idea why this happens. His was setup exactly like mine, except he had dorados. So the rear triangle or chainline are probably not the reason. The fireroad is very simple, so it didn't bottom out, and it had just come back from a service and had no falls on it. But I hope that this new derailleur will work.

I would think it would be good to check for frame flex ...or whatever you call it on a monkey-motion bike.. abnormal stress induced geometry transitions. Anyway sometimes it’s the loose chain that gets snagged by a spoke. A short cage fixes that.

Hopper, I am not saying it is a problem with the model of the bike, but maybe the bike YOU are riding.

Ah, ok, when I took it in. I asked if they could check the frame alignment. He said he didn't reckon that was it. At least I'mk getting a free rebuild, derailleur and possibly chain out of this.

Sorry man but I had to chuckle when I saw the title of this thread "Stuffed up rear end"

Can't it mean both?

Saw your bike in track today...

saw new rear der. Looks good. I think its ur ridiing style serisously i watch you and tell you not to do stuf you do it and you **** your bike..... lol. You ride really hard on you bike but goose's are ment for that

should be all good with small cage der..

Stuffed up rear end?

http://www.ramenterprisesinc.com/products/freelax.jpg

I can't believe I am the only one that thought of this when they saw the post title.

Why would you do it again if its allready been done.... but hay look at ur pic... explains it all lol

Why would you do it again if its allready been done.... but hay look at ur pic... explains it all lol

Couple of things:

1. Learn how to spell, you type like a wounded monkey with down syndrome.

2. I didn't see it was already done, hence the "I can't believe no one thought of this" line.

3. Use of AOL'ese (your vs. ur for example) as I am sure you know is not permitted on this forum.

Couple of things:

1. Learn how to spell, you type like a wounded monkey with down syndrome.

2. I didn't see it was already done, hence the "I can't believe no one thought of this" line.

3. Use of AOL'ese (your vs. ur for example) as I am sure you know is not permitted on this forum.
oh oh oh...the kid is takin' CHARGEEEEE

oh oh oh...the kid is takin' CHARGEEEEE

Beware the wrath of my 155lbs ;)

It's so nice to see members respectfully reminding members of the rules :D

Saw your bike in track today...

saw new rear der. Looks good. I think its ur ridiing style serisously i watch you and tell you not to do stuf you do it and you **** your bike..... lol. You ride really hard on you bike but goose's are ment for that

should be all good with small cage der..

That is almost incomprehensible.

Stuffed up rear end?

http://www.ramenterprisesinc.com/products/freelax.jpg

I can't believe I am the only one that thought of this when they saw the post title.


Hmmm
http://www.ibstales.com/images/products/exlax.jpg
The shifting might be a bit crisper, but I'm curious as to why some of that model exhibt the problem while others are fine.Post #5.
I beat you to it a long time ago.

hey, great minds think alike. :)

Saw your bike in track today...

saw new rear der. Looks good. I think its ur ridiing style serisously i watch you and tell you not to do stuf you do it and you **** your bike..... lol. You ride really hard on you bike but goose's are ment for that

should be all good with small cage der..

Yeah, i think its his riding style... not. How can his riding style affect the fact that he just got it back from the LBS and he was riding down a FIRE ROAD (I was right behind him) on his DH bike and it happened. That shouldnt happen to an XC bike let alone a Downhill bike.

Definately not an issue of style in this case.