MTB: GT avalanch 1.0 niggles , advice plz

CSA · 6 Jun 2013 at 12:42

Hi i bought my GT last november and its been a great bike,i do between 40 and 80 miles a week on it to keep/get fit,however over the last few weeks theres been evidence of wear on the bike and id like to know what stuff i can fix myself and what needs to be looked at by the LBS.

First off the front forks,they have rockshock XC30TK, not the best i know but do for my rides as 95% of the ride i keep them in the locked position but recently i noticed that even when locked theres about 10mm play when i brake or hit a bump,does this mean they need servicing ?

second, the other day i heard abit of a crack from the back end when riding so i stopped and had a look and noticed a metal lug that keeps the chain in place had snapped off the shimano deore XT derailleur,it seems the chain had been wearing through it:

so this has led to two more issues,one is that the chain feels looser and on a couple of occasions when ive geared down to the smallest cog on the back the chain has jumped and got stuck between the small cog and the frame, now its never done this ever before that lug snapped off, could it be because the chain is looser ? would removing one link to tighten the chain fix this ? or am i better off buying a new section to the cage,whats that part called and where would i get one ?

last been not least, as i rode today something snagged on my pants and ripped a hole ,when i looked down to check some kind of bolt had come nearly all the way out from the crank:

the bit with the writting on there, i managed to fasten it back in but only finger tight,it just seems to be a round hole in the middle so i had nothing to tighten it up with,unless theres some kind of special tool for it ? where will i get one of those ?

thanks for reading and hopefully helping

Dis86 · 6 Jun 2013 at 12:50

I'd be taking it back.

Forks should have a little bit of play when locked out but 10mm seems excessive, particularly if you've had nothing before. Although the real judge is how quickly you use the 10mm travel. If just hitting a raised slab of pavement does it, you've got a problem, if it's dropping off a kerb then tbh that's ok.

Not sure what part of the rear derailleur you're referring to but nothing should be snapping off. It'll generally just be a simple part replacement but get your lbs to do it rather than you. Don't start popping links out of your chain.

As for the part of the crank, again not sure what you're referring to, can't see the pic. Nothing should be coming loose though as there are no mobile parts there.

touch · 6 Jun 2013 at 13:04

The bolt on the crank is not an issue. There is very little pressure on it. It is used when you put the cranks on to hold them in place while you do up the 2 pinch bolts on the end of the crank. I think you use an allen key to tighten that up, it's not rounded off though, it's recessed inside the circular hole. Just do it tight enough to hold the bolt on, dont overdo it.

Bits shouldnt snap off your derailleur. The tab that you have circled should not be touching the chain. It sounds as if the chain might have been routed the wrong way. In your photo the chain should go around the bottom of the wheel on the left, under the circled tab and over the top of the wheel on the right.

CSA · 6 Jun 2013 at 13:15

touch said:
The bolt on the crank is not an issue. There is very little pressure on it. It is used when you put the cranks on to hold them in place while you do up the 2 pinch bolts on the end of the crank. I think you use an allen key to tighten that up, it's not rounded off though, it's recessed inside the circular hole. Just do it tight enough to hold the bolt on, dont overdo it.

Bits shouldnt snap off your derailleur. The tab that you have circled should not be touching the chain. It sounds as if the chain might have been routed the wrong way. In your photo the chain should go around the bottom of the wheel on the left, under the circled tab and over the top of the wheel on the right.

Thanks , i did have the chain off the other week to clean it , altho i did take a pic of it before removing it and 100% sure i put it back on the same way lol

before:

after:

touch · 6 Jun 2013 at 13:46

The chain should be in a straight line from where it leaves one wheel to where it meets the other (as it is in your 'after' pic). It's possibly hooked over the wrong side of the tab in the 'before' pic but it's hard to tell.
Losing that tab shouldnt make any difference to the way the bike rides or shifts though.

CSA · 6 Jun 2013 at 14:04

Its definately under the tab on the 1st pic i remember taking a note of its position,what could be causing the chain to get stuck between the smallest cog and bike frame ?

CSA · 7 Jun 2013 at 11:07

So i measured the actual play in the forks using a cable tie,and its actually 3mm

so abit of an over estimate by myself, is 3mm acceptable ?

CSA · 15 Jul 2013 at 12:17

CSA said:
last been not least, as i rode today something snagged on my pants and ripped a hole ,when i looked down to check some kind of bolt had come nearly all the way out from the crank:

thread revival,what is that cover called in the pic ? i appear to have lost it now, must have come loose on my last ride

6thElement · 15 Jul 2013 at 13:51

Bearing preload cap. It's not quite just for holding on the cranks as mentioned above. When you put the crank arm onto the spindle you tighten that end cap sufficiently to take any play out of the crank arm, but not so much that you bind the bearings. Then you tighten the two retaining bolts.

CSA · 15 Jul 2013 at 14:11

Thanks, any idea where i'll get one of these ? ebay and google appear to fail me

touch · 15 Jul 2013 at 14:17

It's a crank bolt.
Here is an example (looks like the right one to me, but best to check the serial number printed on the inside of the crank arm to be sure)

arknor · 15 Jul 2013 at 14:59

You might want to check your gears are indexed properly check some youtube videos.
I've never done it but it looks fairly straight forward.

I think yours might be set to the chain can pull to far to each side which is causing it to rub when you change gears or something especially if the chain has fell off the little cog and got wedged
Theres 2 screws that limit the amount ogf sideways travel the chain has so when you change gear it doesn't try to go beyond the cogs

CSA · 15 Jul 2013 at 15:07

touch said:
It's a crank bolt.
Here is an example (looks like the right one to me, but best to check the serial number printed on the inside of the crank arm to be sure)

thats the bugga ! thanks touch i'll order that now

i'll youtube that , thanks arknor

CSA · 18 Jul 2013 at 15:03

bit of a noob question here but, will the bike be ok to ride without that crank bolt fitted ? i ordered the bolt on monday night from jejames but apparently the messed up my order , ive had to phone em today to track it down and now they saying its being processed but could take 3-5 futher days ? i mean wtf ? lol plus postage costs more than the bolt........

touch · 18 Jul 2013 at 15:17

Yep, that bolt is only needed to locate the cranks when fitting them. Once it's in the correct position, you do up the pinch bolts and that holds the crank in place.

As long as the pinch bolts on the end of the crank are tight, you'll be fine.

CSA · 19 Jul 2013 at 08:26

touch said:
Yep, that bolt is only needed to locate the cranks when fitting them. Once it's in the correct position, you do up the pinch bolts and that holds the crank in place.

As long as the pinch bolts on the end of the crank are tight, you'll be fine.

thanks,hoping to get out for a ride on sunday