GT Aggressor 3 - 2009 to 2011 drive train Questions

[HumpTdumpty]

Hi All - do I need to change these components re drive train purchased recycled 019 pre lockdown/ factory Yr 09 -011 not done anything to it since but love my winter GT run around - ps what type of bottom bracket is it pls ? Starting to jump and skip when applying force through the pedals ? Kind regards as ever HumpTdumpty

 

[Jameshow]

My monies on your middle ring being worn does it skip most on this ring.

A BB won't cause skipping tbh.

Can you dismantle the chainset? If not a new chainset will cost £25 probably.

 

[HumpTdumpty]

Yes your correct J re that jumping for sure many thanks

 

[HumpTdumpty]

Houston “we may have a problem” 6 Bolt bcd ? Does this mean I will require to upgrade to a complete from system - mine now is a 9 speed triple 42/34/24 as I can’t seem to even see a 6 bolt option ? re chain ring only replacements.

Any advice much appreciated

 

[davidphilips]

Looks like your small front chain ring is as worn as the middle and needs replaced, unless you have replaced the chain recently then its also badly worn.

 

[Cycleops]

When it comes to wear in drivetrains if one item is worn you’ll mor than likely need to replace all three items, chain, chainrings and cassette/freewheel.
Unless you can feel a lot of play in the BB that’ll be fine.

 

[Ajax Bay]

@notmyrealnamebutclose maybe has a chainset they are thinking of replacing which is 42-32-22.

 

[T4tomo]

as per above suspect its all worn and a fresh of chainset cassette and chain is needed.

Its a standard square taper BB.

look to replace chainset with something that uses same BB length so the chainline remains the same. good news is sq taper chainsets are pretty cheap, and its probably cheaper than fining two or 3 chainrings

 

[figbat]

It seems that this bolt pattern is unique to Suntour and they no longer sell such cranksets. I agree that a replacement pair of crank arms is the best option, ideally ones with a common, replaceable chainring type. To determine if the bottom bracket needs replacing grab the crank arms and try to rock them side-to-side. If there's some play then you should replace it. Chances are it'll be fine (I am still running a 1997 Trek bike on its original square taper bottom bracket).

 

[Ajax Bay]

Starting to jump and skip when applying force through the pedals?

Agree some of those chainring teeth look over sharp, but please say how many miles you think you've done with the current chain and cassette? Or is the chain quite new? Much more likely to get slip/jump at the sprocket interface of the tensioned chain.

 

[HumpTdumpty]

Many thanks my trusted cycling friends- sounds about right I’ve never replaced any of the drive train since I purchased it recycled from Cambridge bike market store in 019 and I’ve ridden it both here and in Europe flat out since - as recently as last month it got me over the Wrynose and Hardknott passes in Lakes In both directions so I reckon the “old girl” is due some TLC ! Thanks again

 

[Jameshow]

Treat her to something like deore!!

 

[Ajax Bay]

Returning to this thread since you asked on the other thread about changing the cassette.

Hi All - do I need to change these components re drive train purchased recycled 019 pre lockdown/ factory Yr 09 -011 not done anything to it since but love my winter GT run around - ps what type of bottom bracket is it pls ? Starting to jump and skip when applying force through the pedals ? [image of, inter alia, some dirty chainrings]

Houston “we may have a problem” 6 Bolt bcd ? Does this mean I will require to upgrade to a complete from system - mine now is a 9 speed triple 42/34/24 as I can’t seem to even see a 6 bolt option ? re chain ring only replacements. [Image of an MTB chainset with rivetted (x6) rings]

The chainset pictured is rivetted: no bolts involved (try to undo one?).

Agree some of those chainring teeth look over sharp, but please say how many miles you think you've done with the current chain and cassette? Or is the chain quite new? Much more likely to get slip/jump at the sprocket interface of the tensioned chain.

You did not answer this simple question. I'll bet the chain will "jump and skip" on a new chainset. You need a new cassette - the chain has elongated so far that it's slipping and worn out the cassette (some sprockets probably #345, largest is #1).

 

[HumpTdumpty]

Ok so sorry for being dumb try undoing the rivets ok I’ll report back thanks

 

[Ajax Bay]

If you've never changed this chain and been 'all over' in 3 years "bought in 2019 and I’ve ridden it both here and in Europe flat out", for sure the chain is well worn and the cassette likewise. The jumping and slipping is the first (and only) sign that the cassette and chain: you cannot tell by looking. Once the cassette and chain are replaced (*see other thread), if it still slips, then (and only then) replace the chainset (square taper). Inexpensive: £15 for a MTB one new to you with roughly the same rivetted rings and not much more (second hand) for one of those fancy ones with bolts (x 10) and stuff.