What Have You Fettled Today?

[si_c]

Edit:--- Just read someone suggesting online the b-screw adjustment may effect this due to insufficent chain wrap in middle/middle config which is where I get the issue. I have just given that a try and I cannot force it to happen as I could before. Test ride later to confirm.
Rechecked the middle ring too and its probably more worn than I thought, but its not that old, but is a low end shimano one. I might use this as an excuse to get a Spa touring one.

My thought would lean towards a worn middle ring, they're not as easy to tell when they are worn as they are usually chamfered on both sides to aid shifting, like a cassette would be so the tooth profiles are not round.

 

[Ming the Merciless]

Sanded then painted chain stay bridge on recumbent. Winter can be tough on that area and a few areas had got chipped. Now drying for next 16-18 hours or so, before I put mudguard back.

 

[GeekDadZoid]

What's this?

Its the screw that adjusts the rear derailleurs position in a front / back rotation, its normally set to ensure you have enough clearance to get onto the big cog.

My thought would lean towards a worn middle ring, they're not as easy to tell when they are worn as they are usually chamfered on both sides to aid shifting, like a cassette would be so the tooth profiles are not round.

Well I have a trip planned tomorrow so I should be able to see how I go, but I was planning on getting a SPA CHainset at some point anyway so I will probably bring that forward a few months.

 

[si_c]

Its the screw that adjusts the rear derailleurs position in a front / back rotation, its normally set to ensure you have enough clearance to get onto the big cog.

It also has an impact on shifting performance, the b-screw effectively regulates the angle of the upper and lower parallelograms of the derailleur, winding out the b-screw tightens that angle which reduces how crisp the shifts are. This is why a smaller block shifts better if setup correctly as the angles are looser.

Best practice is to set it so that in the largest rear sprocket there is as small as possible a gap between the upper pulley and the largest sprocket, too small and they'll run into each other, which sounds dreadful.

 

[Andy in Germany]

Its the screw that adjusts the rear derailleurs position in a front / back rotation, its normally set to ensure you have enough clearance to get onto the big cog.

It also has an impact on shifting performance, the b-screw effectively regulates the angle of the upper and lower parallelograms of the derailleur, winding out the b-screw tightens that angle which reduces how crisp the shifts are. This is why a smaller block shifts better if setup correctly as the angles are looser.

Best practice is to set it so that in the largest rear sprocket there is as small as possible a gap between the upper pulley and the largest sprocket, too small and they'll run into each other, which sounds dreadful.

Many thanks. I'm taking the attitude that the more I ask the less likely I am to get into problems later in the bike shop I'm leading now: I'm painfully aware that I'm actually a carpenter, rather than a bike wrench, so I've got a lot to learn...

 

[Deleted member 1258]

It also has an impact on shifting performance, the b-screw effectively regulates the angle of the upper and lower parallelograms of the derailleur, winding out the b-screw tightens that angle which reduces how crisp the shifts are. This is why a smaller block shifts better if setup correctly as the angles are looser.

Best practice is to set it so that in the largest rear sprocket there is as small as possible a gap between the upper pulley and the largest sprocket, too small and they'll run into each other, which sounds dreadful.

The Park Tools guide states 5-6mm

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

 

[T4tomo]

Rechecked the middle ring too and its probably more worn than I thought, but its not that old, but is a low end shimano one. I might use this as an excuse to get a Spa touring one.

I had similar on a bike and just popped on a new stronglight middle ring (which spa sell).

 

[si_c]

The Park Tools guide states 5-6mm

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

It probably depends on the derailleur so Park are being a little conservative I think, Shimano suggest as close as possible without not touching which is what I normally do. I only tend to use Shimano stuff on my bikes as I'm familiar with it, I've just taken a look for SRAM and for their latest kit it suggests between 14mm and 5mm depending on your cassette and derailleur . Campagnolo will be different again I guess.

 

[C R]

It probably depends on the derailleur so Park are being a little conservative I think, Shimano suggest as close as possible without not touching which is what I normally do. I only tend to use Shimano stuff on my bikes as I'm familiar with it, I've just taken a look for SRAM and for their latest kit it suggests between 14mm and 5mm depending on your cassette and derailleur . Campagnolo will be different again I guess.

I remember seeing 2mm in a shimano manual, which I thought was quite brave.

 

[GeekDadZoid]

I had similar on a bike and just popped on a new stronglight middle ring (which spa sell).

Unfortunately this is a riveted crankset I was aiming to build this bike on a budget, that's gone way out of the window now and obviously buy cheap buy twice it valid here.

I have done approximately 700km on this pretty much all muddy and wet, and I probably spent a large chunk of that in the middle ring. Still sounds a bit naff.

Edit. Went for a quick spin and it is improved and will be fine for tomorrow, but I can still make it happen if I try hard enough.

 

[DCLane]

Like @GeekDadZoid I had a mechanical earlier today. The rear mech on my Avanti went into the rear wheel on my Avanti, breaking a spoke and wrecking the cage.

After a long walk home it now has a replacement second-hand mech and a new spoke's on order.

 

[T4tomo]

Unfortunately this is a riveted crankset I was aiming to build this bike on a budget, that's gone way out of the window now and obviously buy cheap buy twice it valid here.

I have done approximately 700km on this pretty much all muddy and wet, and I probably spent a large chunk of that in the middle ring. Still sounds a bit naff.

Edit. Went for a quick spin and it is improved and will be fine for tomorrow, but I can still make it happen if I try hard enough.

Ah sounds like it might be new crankset time. Which might also be new BB time too unless you strike upon a replacement that uses same length BB.

You could try your luck used on ebay, but the issue with used triples is the middles ring normally sees the most wear, and it's hard to tell from looking how worn it is, until you try it.

Given how much you seem to use and like that bike though, it prob deserves a new chainset!!

 

[GeekDadZoid]

Ah sounds like it might be new crankset time. Which might also be new BB time too unless you strike upon a replacement that uses same length BB.

You could try your luck used on ebay, but the issue with used triples is the middles ring normally sees the most wear, and it's hard to tell from looking how worn it is, until you try it.

Given how much you seem to use and like that bike though, it prob deserves a new chainset!!

I ordered one last night! As you say I do enjoy riding this bike so it deserves it.

Spa recommend 110mm BB I currently have a 115 on there so I will probably wait for it to arrive and see how the chain line is.

 

[Andy in Germany]

Just looked up Spa. Alas they can't sell in the EU any more...

 

[DCLane]

Bike set-up today for the weekend's activities:

Son no. 2's Argon E116 TT bike was a simple tyre inflation / lights job for a TT on Sunday.

My Ridgeback Platinum was tyre inflation, lubrication, new batteries in everything and kit bag set up for a 400km audax.

Edit the above. He managed to break one of the pad holder bolts on his TT bike on a test ride this evening . It's been dismantled, attempted - and failed -to drill out, and we've just JB-Weld'ed it for now plus tightened the other one.