1x9 small issue

Danieljephcott

Finally completed the 1x9 setup on the wife's bike. Went very easy actually. However in mainly 1st but 2nd also it feels a bit notchy while pedalling. Having a closer look I think it's the bottom little cog on the derailleur arm that's making it notchy. I think while in 1st and second the angle is quite a bit so the chains not going around the cog properly which is causing an issue. Looking at the chainring it's seriously close to the crank so I'm thinking that some pacers might push the chain ring closer to the frame meaning the angle will be less harsh.

Before grabbing some spacers I just wanted to check if this sounds about right.

JGTR

You can measure your chainline and work out if you need to add spacers, it's easy to do and all info is online

Danieljephcott

Ok so I can measure the chain line but I'm confused on what the ideal should be. The bike is a voodoo hoodoo so it was a 3x9. Just replaced the chain rings to a 28t. Defo seems like chainline issues tho.

Danieljephcott

Just measured it and it's 56-57mm. I THINK optimal is 49mm. So essentially do I need a 8mm spacer? Seems quite a bit really.

Sorry I've got a 30t front chainring. It's this one:

http://www.chainreactioncycles.com/mobi ... 7C514892UK

It's already got shims attached but I'm still way out

JGTR

Exactly same chainring as me, I used spacers to get chainline to 50mm.....but my was a 2x beforehand.

Where have you mounted the chainring - outside or middle? If it's the middle and your chainline is still 56-57mm then may have to get new crank?? Other option is to move crank arm closer to frame using spacers on bottom bracket depending what type of BB you have.

I'm no expert BTW, just what I found out when doing mine

Danieljephcott

Chainrings attached to the outer part where my tallest chainring was before. I've got the original bolts which are fairly long so spacers should work. Problem is I'm only finding 2mm spacers which won't be enough.

The bb that I have is: FSA BB7420 square taper. It's a suntour xcm crank

JGTR

Chain ring needs to go in middle position, the spacers go on the outside so you can use your original bolts.

Danieljephcott

Ah sorry it is on the inner.

The Rookie

If its a 28 it can only be on the inner!

What is the chainline (centre of seat tube to centre of chainring)?

Although using the inner tabs it should be fine in first and second as they are always going to be better aligned to the inner chainring location.

Have you checked the B-screw and clearance to the cassette for the upper wheel?

JGTR

The Rookie wrote:

If its a 28 it can only be on the inner!

What is the chainline (centre of seat tube to centre of chainring)?

Although using the inner tabs it should be fine in first and second as they are always going to be better aligned to the inner chainring location.

Have you checked the B-screw and clearance to the cassette for the upper wheel?

He had a 28 on the middle?

He has measured the chainline, its approx 10mm outside what is generally recommended.

Danieljephcott

It seems that in 9th gear the chain is straight with the chainring. In 1st and 2nd the angles probably 15-20 degrees of that makes any sense.

Danieljephcott

Danieljephcott wrote:

It seems that in 9th gear the chain is straight with the chainring. In 1st and 2nd the angles probably 15-20 degrees of that makes any sense.

Also to confirm it's a 30t and the chainline is 57mm

LimitedGarry

Yeah, 8mm is a lot in terms of chainring spacing. Not all setups can get to the optimal chainline, unfortunately.
Surprises me that chainring specific spacers are not way more readily available by today. Although I think an optimal solution would be adaptors of varying lengths that would screw into the nut or threaded hole on the cranks. Would require a special chainring bolt, but IMHO would be better than spacers.

JGTR

Get a new crank? Should be relatively easy and cheap to get a second hand one or even a new one?

Danieljephcott

How would I know which crank to get? Can you point me in the right direction. Could do with getting it sorted before next weekend as that's when we're in Wales.

JGTR

Danieljephcott wrote:

How would I know which crank to get? Can you point me in the right direction. Could do with getting it sorted before next weekend as that's when we're in Wales.

Not sure, you'd need to do some research and looks at specifications and measurements, try and get one that will give better chainline.....if that is what you think the problem is

LimitedGarry

Well, just buy some cheap spacers locally and test the spacing first.

JGTR

LimitedGarry wrote:

Well, just buy some cheap spacers locally and test the spacing first.

Will be quite big spacers (8mm) and will need longer chain ring bolts, if they even make them that long??

The Rookie

A 28 won't fit on the middle position, but of course a 30 can, 57mm is one big chainline offset.

As I recall its a square taper crankset, so a narrower axle seems the best solution.

LimitedGarry

JGTR wrote:

LimitedGarry wrote:

Well, just buy some cheap spacers locally and test the spacing first.

Will be quite big spacers (8mm) and will need longer chain ring bolts, if they even make them that long??

Was drunk last night and kinda forgot he'd need longer bolts. As for what's available, I quite regularly see 9mm in local shops and seen 16mm online.
Anyways, my point I think was for him to test stuff out before he commits to buying something new.

Danieljephcott

I've bought some 3.5mm spacers which are the biggest I could find. That will bring it. Back down to 53ish. I've got the original bolts which should be long enough for with these spacers. See how I get on.

Might do just for a couple of rides at coed y brenin and then I'll sort it properly when I get back