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hesker · 05-10-2015 1:46pm

I have a very similar problem on a build I put together this summer. My build is a bit different in that it's an old steel frame that I've stuck a newer 8 speed group on. But it sounds like there is a similarity here.

No problem on the front small ring at all. No problem on big front ring when on small rear sprockets. When I get to the middle of the cluster changing up to a bigger cog the chain will not climb onto the cog. If I press the shifter a little further it forces it up and then it travels fine with no grinding. I have it adjusted as good as it can get.

I've taken out the cable and relubed it. No difference. Rear der looks fine. Rear der hanger is fine. I suspect the chainline due to the fact that the small front ring gives no trouble. But the chainline looks pretty good.

I've had the wheel out and measured the symmetry of the dropout distance. It's out about 1mm using Sheldon's method of measuring with the string. I may try to correct this but not yet.

I'm going to swap out the rear der and the cranks because I have access to another set. I have measured the chain width and it should be OK with this setup. I might change that out too.

Will let you know if I find anything.

Muckers · 05-10-2015 2:25pm

hesker wrote: »

I have a very similar problem on a build I put together this summer. My build is a bit different in that it's an old steel frame that I've stuck a newer 8 speed group on. But it sounds like there is a similarity here.

No problem on the front small ring at all. No problem on big front ring when on small rear sprockets. When I get to the middle of the cluster changing up to a bigger cog the chain will not climb onto the cog. If I press the shifter a little further it forces it up and then it travels fine with no grinding. I have it adjusted as good as it can get.

I've taken out the cable and relubed it. No difference. Rear der looks fine. Rear der hanger is fine. I suspect the chainline due to the fact that the small front ring gives no trouble. But the chainline looks pretty good.

I've had the wheel out and measured the symmetry of the dropout distance. It's out about 1mm using Sheldon's method of measuring with the string. I may try to correct this but not yet.

I'm going to swap out the rear der and the cranks because I have access to another set. I have measured the chain width and it should be OK with this setup. I might change that out too.

Will let you know if I find anything.

So I'm not the only one who's head is wrecked

iwillhtfu · 05-10-2015 3:09pm

Might be a good time to put in an offer on the new frame

The Kharma is tipping along nicely

Muckers · 05-10-2015 3:24pm

iwillhtfu wrote: »

Might be a good time to put in an offer on the new frame

The Kharma is tipping along nicely

Haha. Small money will secure it now.

dvntie · 05-10-2015 11:57pm

Was just having a think about your issue and was wondering if your rear cable was long enough too. Sram rear mechs are renowned for requiring an unsightly long loop of cable at the mech.

Muckers · 06-10-2015 8:19am

dvntie wrote: »

Was just having a think about your issue and was wondering if your rear cable was long enough too. Sram rear mechs are renowned for requiring an unsightly long loop of cable at the mech.

Seems plenty long. I have Red on another bike with similar loop length and it's so smooth

clog · 06-10-2015 10:20am

Get a straight through length of gear cable outer and run the cable through that outside of the frame itself. If this setup shifrts ok then the problem has to be in the cable run somewhere.

Muckers · 06-10-2015 10:48am

clog wrote: »

Get a straight through length of gear cable outer and run the cable through that outside of the frame itself. If this setup shifrts ok then the problem has to be in the cable run somewhere.

This was suggested to me a few days ago, so that's next on the agenda. Cheers

Junior · 06-10-2015 12:43pm

Are you sure the rear mech isn't slightly bent ?

Muckers · 06-10-2015 5:37pm

Junior wrote: »

Are you sure the rear mech isn't slightly bent ?

Nope. Looks ok. Waiting on this stuff to arrive back from Ribble but the fffn postal strike seems to have slowed it down

Unknown Soldier · 06-10-2015 9:50pm

When you look down at the rear cassette from above, is the rear derailleur arm in line with the sprocket it's under? As in 12 O clock?

Muckers · 06-10-2015 9:52pm

Unknown Soldier wrote: »

When you look down at the rear cassette from above, is the rear derailleur arm in line with the sprocket it's under? As in 12 O clock?

Sure is

Junior · 08-10-2015 8:47pm

Muckers wrote: »

Nope. Looks ok. Waiting on this stuff to arrive back from Ribble but the fffn postal strike seems to have slowed it down

I'd be inclined to give it a little pull - I had a similar issue where I couldn't get a bike to stay in one gear, turns out the rear mech got a slight bend either a pedal up against or something.

Muckers · 16-10-2015 9:00pm

Ok issue resolved as of today. It turns out the inner liners within the down tube to guide the shifter cables through were wrapped around each other. Removal of one of the liners followed by careful reinstallation solved the problem.

Thanks to everyone on here who offered advice and assistance. It is greatly appreciated.

From a happy camper/cyclist

Muckers · 16-10-2015 9:00pm

Ok issue resolved as of today. It turns out the inner liners within the down tube to guide the shifter cables through were wrapped around each other. Removal of one of the liners followed by careful reinstallation solved the problem.

Thanks to everyone on here who offered advice and assistance. It is greatly appreciated.

From a happy camper/cyclist

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