the 'there's no such thing as a stupid question' bike maintenance thread

fryup · 26-03-2021 2:51pm

what's this grub screw for on the brake calipers??

cletus · 26-03-2021 2:57pm

It centres the brake calipers

https://www.parktool.com/blog/repair-help/dual-pivot-brake-service#:~:text=Dual%20pivot%20brakes%20commonly%20have,the%20side%20opposite%20the%20screw.

The relevant passage:

CENTERING

Dual pivot brakes commonly have a centering screw on one arm. Turning the screw clockwise will draw both pads to the side of brake with the screw. Loosening the screw will move both brakes toward the side opposite the screw.

CramCycle · 26-03-2021 2:59pm

fryup wrote: »

what's this grub screw for on the brake calipers??

Sh1ts and giggles

In all seriousness though, I think its alignment after you tighten the brakes up to the frame

fryup · 26-03-2021 6:24pm

^^^^^^^^

and what's with the giggle?

CramCycle · 26-03-2021 7:07pm

fryup wrote: »

^^^^^^^^

and what's with the giggle?

I repair a lot of scientific equipment and the amount of times there are parts that are completely redundant is incredible. Now most of the time it is a leftover from previous models and it was never reviewed or it was designed by a scientist and built by an engineer and never the two ever talk to each other. So you often find bits and pieces that serve no purpose other than too look like they do.
So I always think it's just some ****h*** of a designer put them there for sh1ts and giggles, i.e. to get a laugh out of the number of people who will think they are essential or spend inordinate amounts of time trying to use or figure out their purpose.

cletus · 26-03-2021 7:16pm

And tell me, cramcycle, do you often have equipment that you no longer require, and that you subsequently may wish to give to random people on the internet, like, for example, a bench power supply, or oscilloscope...

CramCycle · 26-03-2021 11:08pm

cletus wrote: »

And tell me, cramcycle, do you often have equipment that you no longer require, and that you subsequently may wish to give to random people on the internet, like, for example, a bench power supply, or oscilloscope...

Drop me a PM with a list of what you are looking for, and if it ever comes up for disposal I will let you know (I gave an oscilloscope away a few months ago). I always actively search out alternative users rather than waste disposal. If I can find a good home and it poses no danger, it is yours.

cletus · 26-03-2021 11:11pm

CramCycle wrote: »

Drop me a PM with a list of what you are looking for, and if it ever comes up for disposal I will let you know (I gave an oscilloscope away a few months ago). I always actively search out alternative users rather than waste disposal. If I can find a good home and it poses no danger, it is yours.

My post was tongue in cheek, but I'd absolutely take you up on that very kind offer. My list is in my last post...bench power supply and oscilloscope.

Cheers Cram

27-03-2021 12:46am

I'll take a flux capacitor Cram if you get one going to waste.

Weepsie · 27-03-2021 12:55am

Not a question, but an observation.

While swapping out a 105 group set for a tiagra one I couldn't noticed the tiagra front derailleur is very marginally wider so had to be clamped slightly higher.

I had a big I am an idiot moment when I realised

magicbastarder · 27-03-2021 1:01am

fryup wrote: »

what's this grub screw for on the brake calipers??

this is not going to help, but what's all the dirt on the bike? it's very pale; is that sawdust?

Type 17 · 27-03-2021 1:00pm

magicbastarder wrote: »

this is not going to help, but what's all the dirt on the bike? it's very pale; is that sawdust?

Pale grit/sand from cycling in heavy rain, it looks like the stuff you wash out of the wheel-arches of a car.

It's likely that the centring screw (and the calliper in general) is seized

fryup · 27-03-2021 2:19pm

magicbastarder wrote: »

this is not going to help, but what's all the dirt on the bike? it's very pale; is that sawdust?

sawdust? what do you take me for a lumberjack?

no, its just dry muck

magicbastarder · 27-03-2021 2:25pm

fryup wrote: »

sawdust? what do you take me for a lumberjack?

yeah, but you're OK.

54and56 · 27-03-2021 4:37pm

07Lapierre wrote: »

I don’t think disc brakes make much difference to a cleaning routine. The main difference is you have to be very careful and ensure you don’t contaminate disc brake rotors.

I use hot soapy water for cleaning my bikes. I use biodegradable degreaser (from Halfords) and I use Muck off dry and wet lube.

I do similar weekly mileage and I clean my commuter bike once a week.

No good deed goes unpunished

Now that I'm doing regular weekly cleaning of course I've somehow managed to contaminate my front disc brake which is making a horrible loud screeching sound just as the bike comes to a halt. There's no screeching initially, just at the very end when the brake "bites" if that makes sense.

Should I just leave it for a few spins and see if it sorts itself out or should I clean the rotor with isopropyl alcohol to sort it out and if that doesn't work clean the pads as well?

cletus · 27-03-2021 5:33pm

54and56 wrote: »

No good deed goes unpunished

Now that I'm doing regular weekly cleaning of course I've somehow managed to contaminate my front disc brake which is making a horrible loud screeching sound just as the bike comes to a halt. There's no screeching initially, just at the very end when the brake "bites" if that makes sense.

Should I just leave it for a few spins and see if it sorts itself out or should I clean the rotor with isopropyl alcohol to sort it out and if that doesn't work clean the pads as well?

The discs can be cleaned as you describe.

If the pads are contaminated, they can be sanded lightly

magicbastarder · 27-03-2021 6:34pm

i usually clean pads by dropping them into boiling water for a bit, running a heat gun on them, and/or a light scuffing with fine sandpaper.

EDit · 28-03-2021 4:48pm

job of changing rear derailleur has morphed into a need to change rear gear cable (when the old derailleur was removed, the cable was found to be seriously frayed and trying to tidy it up has only made things worse)

Anyway, question is whether replacing rear gear cable is really as straightforward as the various YT videos make it out to be? The bike is a giant TCR (2019) and has internal cabling (if that makes a difference)

cletus · 28-03-2021 5:02pm

Internal cables make it a bit more tricky, but in general terms, yes changing cables is easy.

If you're only changing the cable, and not the outer, leave that in place, it'll be easier to thread through.

Get yourself a good pair or cable cutters, it'll help prevent fraying of the cut end

wersal gummage · 28-03-2021 11:01pm

Building up a bike on di2, my first experience with di2.

Groupset has the older junction box which is normally attached under the stem.

I know I can buy a rs910 unit which goes in the bar end, and that seems like the handiest option to slightly hide some cables....

I'm also considering buying the d fly / Bluetooth /ant module thing...

So I've a few questions if anyone has experience or views on this...

I've bought handlebars with internal routing, and a small hole where the bars meet the stem (but the stem I've bought has no exit for wires so I will need to run a cable from the bar to the frame in the normal way).. Anyway, I'm wondering if I can stick the old style junction box IN the stem? I gather this could be a nuisance as it's used for charging and other things? But charging, for me, should be once or twice between now and putting the bike away for winter.... So I think I can live with that.... I think I need access to this box to index the gears initially, but I can leave it hanging out and then hide it away once that's done. Anything I'm missing??

On the Bluetooth / ant module, this allows connection to garmin and phone, seems a bit of a gimmick?? It's nice to see what gear I'm in etc, but I can survive without this.. Is it a must have?

I'm thinking if I had the junction box in the stem, the Bluetooth module would let me see the battery percentage and would make life easier by not having to take the stem plate off to press the little button to check battery flashing lights?

I know the answer is probably buy both but I'm getting slightly fed up at the extent of the outlay already with covid pricing / availability and trying to limit further spending now unless really necessary.

Grateful for any help, if anything I've said makes any sense at all.

07Lapierre · 29-03-2021 8:10am

cletus wrote: »

Internal cables make it a bit more tricky, but in general terms, yes changing cables is easy.

If you're only changing the cable, and not the outer, leave that in place, it'll be easier to thread through.

Get yourself a good pair or cable cutters, it'll help prevent fraying of the cut end

If the cable was worn so badly that the end was frayed (at the shifter end), I’d recommend replacing the cable and the housing. Internal cables are tricky, so all the more reason to replace everything so you don’t have to do it again for a long time.

TerryDi2Center · 29-03-2021 9:53am

wersal gummage wrote: »

Building up a bike on di2, my first experience with di2.

I've bought handlebars with internal routing, and a small hole where the bars meet the stem (but the stem I've bought has no exit for wires so I will need to run a cable from the bar to the frame in the normal way).. Anyway, I'm wondering if I can stick the old style junction box IN the stem? I gather this could be a nuisance as it's used for charging and other things? But charging, for me, should be once or twice between now and putting the bike away for winter.... So I think I can live with that.... I think I need access to this box to index the gears initially, but I can leave it hanging out and then hide it away once that's done. Anything I'm missing??

I really would like to have the junction A accessible at all times.

Depending on your shifting habits you may have to charge the bike every 2000-4000km.
The button on the junction lets you switch between shift modes (full/semi synchro, manual mode) and micro-adjust (index) the rear derailleur as you ride.
Also, the LEDs on the junction will tell you the battery charge level and the button can also be used to reset the RD if it has gone into crash mode.

wersal gummage wrote: »

On the Bluetooth / ant module, this allows connection to garmin and phone, seems a bit of a gimmick?? It's nice to see what gear I'm in etc, but I can survive without this.. Is it a must have?

I'm thinking if I had the junction box in the stem, the Bluetooth module would let me see the battery percentage and would make life easier by not having to take the stem plate off to press the little button to check battery flashing lights?

True, I guess that's an option too

The Wireless module lets you change settings and update firmware.. and see the current gear / battery level on your garmin.
Personally I prefer to update firmware using the junction and a Windows PC.. it just feels a bit safer ;-)

Mundo7976 · 29-03-2021 10:22am

Lads, wheres the best place to buy brake bleed kits that aren't mad expensive, but are capable of performing a job on 2 bikes more than once?

gaffmaster · 29-03-2021 10:47am

wersal gummage wrote: »

On the Bluetooth / ant module, this allows connection to garmin and phone, seems a bit of a gimmick?? It's nice to see what gear I'm in etc, but I can survive without this.. Is it a must have?

This can also be used to operate your bike computer with your hidden buttons (on top of the hoods) - scroll through screens etc. I have mine set up like this and it's handy to access the map without your hands leaving the hoods.

In terms of location for the Bluetooth module, my mechanic pluggedd mine into the seat-post battery - which makes it accesssible when you pull the seatpost out. If you really didn't want to buy the bar-end Junction-A, you could look into rigging it to the battery with a short cable and using longer cables to your shifters (I've never done this and not sure if it would work/fit in the seat tube). Also get some foam to wrap and giblets like this to prevent rattles.

wersal gummage · 29-03-2021 11:20am

Thanks yes was thinking Bluetooth module in seat tube alright...

I know better to buy both things but janey it's looking like over 200 euro plus cables and I've already spent nearly twice the nornal (eg discount available) on a groupset so it's starting to get ridiculous

Edit, plus the cables....

MojoMaker · 29-03-2021 12:19pm

Question about cross-compatibility of Shimano mechanical road groupsets. I'm wondering if R7000 STIs are fine to mate to R8000 RD and possibly either 6800/7000/8000 FD?

I assume no issue but don't want to waste money if there's going to be a glitch in my thinking.

8valve · 29-03-2021 1:20pm

Mundo7976 wrote: »

Lads, wheres the best place to buy brake bleed kits that aren't mad expensive, but are capable of performing a job on 2 bikes more than once?

Alligator and BBB do generic universal kits that are fine for home use; widely available online. Both come with a variety of fittings to fit most popular brands.

Any good pharmacy will sell you syringes without needles for pennies...and give you funny looks when you ask for them.

Shimano and Tektro also do their own brand specific kits.

Weepsie · 29-03-2021 2:34pm

MojoMaker wrote: »

Question about cross-compatibility of Shimano mechanical road groupsets. I'm wondering if R7000 STIs are fine to mate to R8000 RD and possibly either 6800/7000/8000 FD?

I assume no issue but don't want to waste money if there's going to be a glitch in my thinking.

Only one I know of that's weird is Tiagra 4700 won't work with any other 10 speed stuff, but it curiously work with the 11 speed stuff as in the derailleurs will work with 11 speed shifters apparently.

Mundo7976 · 29-03-2021 5:16pm

8valve wrote: »

Alligator and BBB do generic universal kits that are fine for home use; widely available online. Both come with a variety of fittings to fit most popular brands.

Any good pharmacy will sell you syringes without needles for pennies...and give you funny looks when you ask for them.

Shimano and Tektro also do their own brand specific kits.

Thanks. Will orddr a BBB one later. All i could see was the cheapo looking yellow ones when looking. Wouldn't have much confidence in them

tomasrojo · 29-03-2021 6:23pm

This is more of a pre-emptive question; I don't currently have a problem, but it might eventually be a problem.

Due to corrosion, I've had to peel a bit of insulation off the wire going into the Shimano spade that connects the head lamp to the front wheel hub dynamo, to expose fresh, uncorroded wire. This means that connecting wire is getting a bit shorter. I presume it's practical to just splice some new wire in place if it gets too short, and wrap insulating tape around the join?

cletus · 29-03-2021 6:27pm

Splicing very short pieces of wire can be tricky, otherwise don't see an issue with it.

I wouldn't use insulating tape, it just turns into a sticky mess. Get some heat shrink tubes instead

Type 17 · 29-03-2021 7:32pm

MojoMaker wrote: »

Question about cross-compatibility of Shimano mechanical road groupsets. I'm wondering if R7000 STIs are fine to mate to R8000 RD and possibly either 6800/7000/8000 FD?

I assume no issue but don't want to waste money if there's going to be a glitch in my thinking.

Shimano's own chart: https://productinfo.shimano.com/#/com?acid=C-454&cid=C-453

CianRyan · 29-03-2021 7:37pm

cletus wrote: »

Splicing very short pieces of wire can be tricky, otherwise don't see an issue with it.

I wouldn't use insulating tape, it just turns into a sticky mess. Get some heat shrink tubes instead

I'll add to this, if you're not handy with a soldering iron, you can buy heat wrap with solder rings in them. Not as good as a proper job but a loop and twist with one of those bad boys is way more fool proof!

triggermortis · 29-03-2021 8:18pm

tomasrojo wrote: »

This is more of a pre-emptive question; I don't currently have a problem, but it might eventually be a problem.

Due to corrosion, I've had to peel a bit of insulation off the wire going into the Shimano spade that connects the head lamp to the front wheel hub dynamo, to expose fresh, uncorroded wire. This means that connecting wire is getting a bit shorter. I presume it's practical to just splice some new wire in place if it gets too short, and wrap insulating tape around the join?

These are what you need....

https://ie.farnell.com/raychem-te-connectivity/cwt-3802/solder-sleeve-po-clear/dp/2765539?gclid=Cj0KCQjw9YWDBhDyARIsADt6sGb2SgZsqYap6pGutH08YOkFHQ8YuLZmEqn_r468AS4L0KUxFIu4nnIaAoGqEALw_wcB&mckv=sQwoQDMGy_dc|pcrid|473404530606|kword||match||plid||slid||product|2765539|pgrid|118346197384|ptaid|pla-296811702606|&gross_price=true

just strip the wires, put inside this and heat up until the solder melts. Heat the ends to fully seal the splice

tomasrojo · 29-03-2021 9:12pm

Great, thanks everyone. As I say, not needed yet but will be needed eventually.

cletus · 29-03-2021 9:32pm

If you have and can use a soldering iron, I'd use that before one of those solder ring things. At least if you solder the joint yourself, you know it's done well.

As an aside, if you have enough cable, look up lineman splice, a good strong joint that offers mechanical strength, and is also streamlined, so the heat shrink fits over it nicely

MojoMaker · 29-03-2021 9:42pm

Type 17 wrote: »

Shimano's own chart: https://productinfo.shimano.com/#/com?acid=C-454&cid=C-453

Much appreciated and handy link to boot.

Just so I'm reading it correctly, looks like the rear compatibility is virtually homogenous across the 11spd offerings, but the front compatibility is a little more sensitive. Looking at the chart the R7000 left hand shifter will work with the older 6800 and 5800 FD, but the R8000 left shifter will only work with the newer 7000, 8000, and 9100 front derailleurs? (and oddly the 5801 FD).

Either way, question answered and I know what to cross match now, but that's annoying me.

kirving · 29-03-2021 11:18pm

cletus wrote: »

If you have and can use a soldering iron, I'd use that before one of those solder ring things.

I would too to be honest, but I can solder pretty well as I don't often enough in work. In a pinch though, those solder sleeves are absolutely fantastic.

Large bottle small glass · 30-03-2021 8:06am

tomasrojo wrote: »

Great, thanks everyone. As I say, not needed yet but will be needed eventually.

I recently used gel connectors for connecting dynamo cables. Recently simple, 2 second job gentle squeeze with a pliers

Friend works in IT he uses them all the time

Type 17 · 30-03-2021 2:03pm

MojoMaker wrote: »

...the front compatibility is a little more sensitive. Looking at the chart the R7000 left hand shifter will work with the older 6800 and 5800 FD, but the R8000 left shifter will only work with the newer 7000, 8000, and 9100 front derailleurs? (and oddly the 5801 FD).

Actually, I think that any shifter in the left box will work with any FD in either of the two centre boxes, but the FDs are split into two boxes because they want to confirm the limitation that the lower box (older FDs) will not work with the upper FC box (newer chainsets), but that the newer FDs (upper box) will work with both older and newer FCs.

Mundo7976 · 31-03-2021 8:34am

Hey. Can ye recommend what disc brake pads to get for trp hyrd please. Preferably ones that dont shudder or squeal. Thanks

magicbastarder · 31-03-2021 8:42am

it's not the brake pads which are to blame for that really; yours could be contaminated. does the braking performance drop off alarmingly in the wet?

Mundo7976 · 31-03-2021 10:12am

magicbastarder wrote: »

it's not the brake pads which are to blame for that really; yours could be contaminated. does the braking performance drop off alarmingly in the wet?

As in the pads contaminated?
Haven't noticed much difference in the wet, then again i take it easier when cycling in wet conditions (id be quite a cautious cyclist)
Would rotors need replacing also?
Its mainly the front that shudders, ive checked & tightened headset. Made sure brakes are aligned correctly, etc so i was putting it down to my weight behind it.
The rear brake squeals more so i have that down to needing new pads + bleed.

cletus · 31-03-2021 10:24am

I'd try cleaning pads and disc first. Easy to do, and cheaper than replacing

magicbastarder · 31-03-2021 10:26am

Mundo7976 wrote: »

Would rotors need replacing also?

no, just a light rub with some emery cloth/fine sandpaper at worst.

CianRyan · 31-03-2021 10:27am

Shudder is down to warped dics on a car, I'm going to make a leap and say that it's probably the same on a bike.
If you're replacing dics, I'd always replace pads too.

magicbastarder · 31-03-2021 10:30am

it can be an issue with contamination - which is usually less of an issue with cars because AFAIK, bike pads don't generate the same heat to burn off contamination that cars would.
shudder on bike brakes can also be caused by incorrect toe-in, though i don't know how much of an issue that can be on disc brakes.

cletus · 31-03-2021 10:30am

CianRyan wrote: »

Shudder is down to warped dics on a car, I'm going to make a leap and say that it's probably the same on a bike.
If you're replacing dics, I'd always replace pads too.

I'm not sure it is, Cian. Don't know if you'd be generating enough heat

magicbastarder · 31-03-2021 10:31am

brake pads are amazing, if you think about it. especially with cars; just think of the energy they're expected to absorb time after time. in several seconds, they can absorb the same sort of energy which would otherwise be enough to write your car off.

Mundo7976 · 31-03-2021 10:40am

Fair play lads.
Rotors seem straight by eye.
Ive some 400grit sandpaper ill use on them and replace pads, see if it helps

the 'there's no such thing as a stupid question' bike maintenance thread

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