Gear glitch

[TSema]

After riding for about 60km’s on the weekend my Shimano 105 groupset momentarily glitched and refused to change to the big ring upfront. I stopped, picked the back wheel up and tried changing to the big ring in the front and it changed, I then carried on and completed my ride with the bike changing as it should. I am just wondering why did it hesitate to change (this is the second time I experienced this), the gear shifter had no resistance as I pushed it to move to the big ring but after a few minutes it changed as normal. Do I need to replace the cables or is it something else?

[100Tours]

Please excuse the lack of bike-appropriate technical language in this description. I'm sure there are proper names for these things.

The shift lever has a little tooth/ratchet that engages the actual shift mechanism inside of the lever to shift the gear. The lever bites against the ratchet to shift, moves the gear, the ratchet locks into the new position, and then the lever returns 'free' back to its starting position - ready for another shift. When you down-shift, the 'locked' ratchet releases and drops back into its original position in the smaller gear. This should also put the ratchet back in position against the lever for the next upshift.

It sounds like the tooth/ratchet is not consistently re-engaging after your downshift (or you were already in the big ring position, despite the chain being on the small ring).

There are 3 potential issues. either wear, dirt or tuning. You can try clean out the lever (soapy water, Q20) and this may improve the shifting. Also depending on the model you can sometimes check that nothing has loosened up in the shifter that is causing it to miss. You should also check that the shift cable is not overtight when in the big ring (the little limit screw may be holding the shift cable in tension when you're in the big ring, and the extra tension may be fouling the release).

You can also sometimes fix this issue by false-shifting the downshift lever to help things settle back into position. i'e' the chain moved, but the mechanism didn't quite reset.

Alternatively it is wearing out. in this case you are likely looking for a new lever at some stage. I'm not aware of many successful repairs on these.

I would do the following:

1. disconnect the FD. check that the lever is shifting nicely on its own. This may reveal the issue - it should shift cleanly and freely. If you need to clean it or fiddle with the shift cable inside this will now be obvious.

2. set the lower limit on the FD with the cable still disconnected. Chain should run cleanly on the small ring in the biggest cog.

3. Reconnect cable and check upshift. Make sure the top limit screw is not too tight to interfere with the shift.

 

 

 

Edited September 5, 2022 by 100Tours

[TSema]

Thanks mate, helpful info!

[Barry]

29 minutes ago, TSema said:

Thanks mate, helpful info!

You could also blast the shifter mechanism with Q20 it will clean out shifter. Sometimes the grease gets hard or dust builds up. Can also flush it with boiling water.

More permanent solution would be running campy😂

[love2fly]

Before you get too technical chasing problems check the outer limit screw and cable tension. Try to **** it as normal - then put a finger under the cable to add tension near the derailleur - can it move more? If NO back the adjust screw out 1/4 to 1/2 a turn. If YES then give the cable a bit more tension. Try to avoid Q20 into your shifter as those type of sprays are often silicone based and silicone is a dust magnet. Rather spray out with brake cleaner with bike standing upright. Once dry lube with a bit of dry chain lube or a little wet chain lube or regular oil. Less is more.

Funnily enough what seems to be the case for front derailleur cable tension - often instinct says you need more cable tension when you actually need less. For such a small component it can give you a lot of **** 😀.

How old are your cables & housing?

[Barry]

18 minutes ago, love2fly said:

Before you get too technical chasing problems check the outer limit screw and cable tension. Try to **** it as normal - then put a finger under the cable to add tension near the derailleur - can it move more? If NO back the adjust screw out 1/4 to 1/2 a turn. If YES then give the cable a bit more tension. Try to avoid Q20 into your shifter as those type of sprays are often silicone based and silicone is a dust magnet. Rather spray out with brake cleaner with bike standing upright. Once dry lube with a bit of dry chain lube or a little wet chain lube or regular oil. Less is more.

Funnily enough what seems to be the case for front derailleur cable tension - often instinct says you need more cable tension when you actually need less. For such a small component it can give you a lot of **** 😀.

How old are your cables & housing?

 Spanjaard cold clean spray also works well for sorting the shifter. Yes a littil wet lube after and should be good for few more years. Brake cleaner is very harsh works well but make sure you clean up after.

[love2fly]

7 minutes ago, Barry said:

 Spanjaard cold clean spray also works well for sorting the shifter. Yes a littil wet lube after and should be good for few more years. Brake cleaner is very harsh works well but make sure you clean up after.

Brake cleaners are generally alcohol based andnot harsh at all. It's very similar to degreaser but doesnt leave a residue. It's perfect for this function. 

Edited September 7, 2022 by love2fly

[Barry]

10 minutes ago, love2fly said:

Brake cleaners are generally alcohol based andnot harsh at all. It's very similar to degreaser but doesnt leave a residue. It's perfect for this function. 

What brand do you use? Will give it a bash. I find Spanjaards make some cool products. Quick easy cleaning of headset, freehubs and anything you need squeaky clean😂

[TSema]

Bought the bike used, its a 2017 model, doubt the cable and housing were changed so tempted to start there. How often should one change these?

[love2fly]

35 minutes ago, Barry said:

What brand do you use? Will give it a bash. I find Spanjaards make some cool products. Quick easy cleaning of headset, freehubs and anything you need squeaky clean😂

Yip. Nothing wrong with Spanjaards.

For cleaning where bearings seat like BB 's and headsets, freehubs etc I get rubbing alcohol from the pharmacy. I guess brake cleaner works too.

[Schnavel]

8 minutes ago, TSema said:

Bought the bike used, its a 2017 model, doubt the cable and housing were changed so tempted to start there. How often should one change these?

It depends on how often you ride, as well as in what conditions. 

If you are riding in decent weather conditions (not heavy rain etc), I have found that changing the cable every 10000km works well.

[love2fly]

7 minutes ago, TSema said:

Bought the bike used, its a 2017 model, doubt the cable and housing were changed so tempted to start there. How often should one change these?

As to how often in my experience as soon as you get a delayed down shift its time. Can also be the cause of your problem. On some frames, like my Cannondale Supersix I get juice droplets finding their way under the BB into the cable routing guide. I clean that and very light grease maybe twice a year.

If its a secondhand bike it's a good idea to replace shift cable and housing. Brake cable and housing lasts longer - gets less use.

[droo]

11 speed?

If it is, change your cables ASAP, or prepare for your cable to snap mid-ride and be an absolute hack to replace.

There's a sharp bend in the lever that causes the cable to fray and eventually snap inside the lever, and what you're experiencing may be the start of that.

If that doesn't solve your problem, then proceed to the spritzing solutions.

[TSema]

Any recommendations where in JHB I can get new cables and housing fitted at a reasonable price?

[The Ouzo]

1 hour ago, droo said:

11 speed?

If it is, change your cables ASAP, or prepare for your cable to snap mid-ride and be an absolute hack to replace.

There's a sharp bend in the lever that causes the cable to fray and eventually snap inside the lever, and what you're experiencing may be the start of that.

If that doesn't solve your problem, then proceed to the spritzing solutions.

I was reading through all the comments and was about to reply with what Droo commented above. 
my 105 rear shifter did exactly this. 

[porqui]

2 hours ago, TSema said:

Any recommendations where in JHB I can get new cables and housing fitted at a reasonable price?

Nope you do it yourself - you are a cyclist.