middleburn chainrings

[barreti]

Well, I thought my outer ring - the big one - was shot and was looking for a replacement. It turns out it may not be, because it looks like the 32tooth jobbie at the top of the page
here

Sorry to be a numpty but can someone explain why there appear to be broken teeth on this ring.

At the risk of appearing completely stupid too...
I can't get the front shifter to come close enough in to pull the chain to the smallest ring. I'm not particularly bothered about this at the mo but I wondered if I did want to do anything about it, is it the shifter I should change or get a better range of gears on two rings using something like the Middleburn Duo range?

[pdV6]

barreti said:

Sorry to be a numpty but can someone explain why there appear to be broken teeth on this ring.

To let the chain get on and off the teeth.

barreti said:

At the risk of appearing completely stupid too...
I can't get the front shifter to come close enough in to pull the chain to the smallest ring.

First thing to check is the limit screws on the shifter - they set the max inboard (L) and outboard (H) positions of the shifter. Best checked with the gear cable pinch bolt loosened off so that the shifter/cable tension doesn't affect what you're seeing.

[barreti]

I've fiddled with the screws and got them wound so far out they practically fall out of the shifter!
When the handlebar shifter is fully shifted down (up?) the cable to the shifter is completely slack, so it seems I've got it released as far as it will go.
I got the bike 2nd hand so I wonder if shifting to all 3 cogs ever worked?
For that matter, the back shifter doesn't extend out enough to get to the most outboard gear (smallest cog) which is gear #9
I've got an xt deore back there which I suspect thats an 8 gear shifter and somebody has been playing about with cog sets.

[pdV6]

barreti said:

For that matter, the back shifter doesn't extend out enough to get to the most outboard gear (smallest cog) which is gear #9
I've got an xt deore back there which I suspect thats an 8 gear shifter and somebody has been playing about with cog sets.

The total range of motion for an 8sp or a 9sp rear mech is the same; its just the incremental shifts (governed by the shifter) that make the difference (that and the fact that the cogs & chain are narrower for 9sp to fit in the same physical gap as an 8sp setup). Therefore if your shifter won't "reach" out to the highest (smallest) cog, the limit screw and/or the cable tension are out of adjustment.

Assuming nothing's bent out of shape of course.

[barreti]

aha. thanks for that. I don't think anything is bent and it all looks in good nick back there so perhaps I'll just have a play with the deraileur thingy.

[pdV6]

- Chain off
- Gear cable pinch bolt undone
- Adjust L limit screw until top jockey wheel is directly under largest cog
- Push mech out as far as it will go and hold it there
- Adjust H limit screw until top jockey wheel is directly under smallest cog
- Shifter into highest gear (8 or 9)
- Pull gear cable through rear mech as far as it will go
- Nip up pinch bolt
- Check indexing of gears, adjust as necessary via barrel adjuster on shifter pod (1/4 turn at a time)

[beyond rational]

Some front mechs just won't reach the inside chainring because of the bottom bracket spidle length and the thickness of certain parts on the mech itself.

- Bike in car
- Bike Shop
- Wallet out
- Bend over

[dight-s]

Confused by some of the replies! Are we not talking front mechs here? If so, and you have wound the L screw out and your cable tension is loose, it suggests to me that the bottom bracket has been replaced at some stage with one that is to short. Does the mech look reasonably new? Sometimes as they get older the spring loses some of it's power then in would pull in as effectively.

Dan.

Nice looking Grif BTW

[pdV6]

dight-s said:

Confused by some of the replies! Are we not talking front mechs here?

We were but then shifted (see what I did there?) to rears.

[beyond rational]

Its all got a bit confusing