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ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
If you need 40% more stopping power, then something is up and I bet it isn't the length of your brake pads!
I can lock my wheels when braking with one or two fingers on the brake levers, so no extra braking power is required. Those pads are about 50mm long.
Are your wheel rims clean? I had a near miss on a steep descent when my brakes were struggling to slow me down. The problem turned out to be a filthy greasy film on the rims.
I can lock my wheels when braking with one or two fingers on the brake levers, so no extra braking power is required. Those pads are about 50mm long.
Are your wheel rims clean? I had a near miss on a steep descent when my brakes were struggling to slow me down. The problem turned out to be a filthy greasy film on the rims.
ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
[QUOTE 5528638, member: 9609"]No, they're never clean, and yes they do work better when I have spent ages getting them clean with white spirits etc, but that takes too much time.
[/QUOTE]
I used to use wet wipes on the rims, but decided that they are not great for the environment so now I just use a bit of old rag and some warm water with washing up liquid in. That seems to get them clean enough and doesn't take too long.
[QUOTE 5528638, member: 9609"]
But generally they're pretty rubbish in the wet. They're always adequate in the dry, but wet days they're bloody awful.[/QUOTE]
When I posted ...
You might be able to find a different brake pad compound which works better in the wet, but I still reckon a quick scrub of the rims would be the answer.
[/QUOTE]
I used to use wet wipes on the rims, but decided that they are not great for the environment so now I just use a bit of old rag and some warm water with washing up liquid in. That seems to get them clean enough and doesn't take too long.
[QUOTE 5528638, member: 9609"]
But generally they're pretty rubbish in the wet. They're always adequate in the dry, but wet days they're bloody awful.[/QUOTE]
When I posted ...
... that would be one finger with dry rims, but two fingers needed when the rims are wet.
You might be able to find a different brake pad compound which works better in the wet, but I still reckon a quick scrub of the rims would be the answer.
ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
Here's what the wet wipes looked like after I cleaned the rims after nearly shooting out onto an A-road at the foot of a steep, wet descent!
NorthernDave
Never used Über Member
- Location
- The real Northern Powerhouse
What pads are you using?
I upgraded to Swissstop BXPs and noticed an immediate improvement. Others swear by Koolstops.
If it's wet a quick on/off, then apply again helps with rim brakes as it clears some of the muck off the rims.
Edit to add: that said, I've got disc brakes on all my bikes now.
I upgraded to Swissstop BXPs and noticed an immediate improvement. Others swear by Koolstops.
If it's wet a quick on/off, then apply again helps with rim brakes as it clears some of the muck off the rims.
Edit to add: that said, I've got disc brakes on all my bikes now.
Last edited:
mynydd
Veteran
This is why I’d only ever consider a bike with hydraulic disks now.....
I’ve spent years doing a lot of hilly winter commuting in all weathers..... and was sick of cleaning rims, constantly buying new pads / wheels etc. And still not being able to stop in certain conditions...... stopping is underrated
Sorry, that doesn’t really answer you question does it
I’ve spent years doing a lot of hilly winter commuting in all weathers..... and was sick of cleaning rims, constantly buying new pads / wheels etc. And still not being able to stop in certain conditions...... stopping is underrated
Sorry, that doesn’t really answer you question does it
Yellow Saddle
Guru
- Location
- Loch side.
[QUOTE 5528554, member: 9609"]would 72mm pads fit on Caliper-rim-type brakes that currently have 52mm pads ?
and if they did would they give about 40% more stopping power?[/QUOTE]
No, friction doesn't work like that. You get exactly the same friction (all else, such as rim type and rubber type and lever advantage, remains the same) with a small or large pad. Friction is what stops you. Let's call it stopping power, if you like.
A longer pad simply lasts longer, but it has to be curved, otherwise it doesn't fit on the rim and eats tyres.
Get decent pads. I swear by Koolstop salmon or red.
and if they did would they give about 40% more stopping power?[/QUOTE]
No, friction doesn't work like that. You get exactly the same friction (all else, such as rim type and rubber type and lever advantage, remains the same) with a small or large pad. Friction is what stops you. Let's call it stopping power, if you like.
A longer pad simply lasts longer, but it has to be curved, otherwise it doesn't fit on the rim and eats tyres.
Get decent pads. I swear by Koolstop salmon or red.
BianchiVirgin
Über Member
- Location
- Norn Iron
Eh? Larger pads will create more friction and therefore more stopping power. Otherwise pads could be 1mm long by your theory. There has to be a proportionate increase in friction. So friction does work like that.
Yellow Saddle
Guru
- Location
- Loch side.
You may want to do a bit of reading and then reconsider your understanding of friction.
[QUOTE 5529136, member: 9609"]Would the leading edge of a longer pad not be more likely to dry the rim so the trailing end of the pad could get a better grip ?
I think my biggest error is letting the pads get smooth before replacing them, once they are smooth they become useless in the wet.
may be not, but it's good to know I'm not the only one who struggles with braking in poor conditions. one run last week I was coming down a hill in wet slushy conditions and at best the brakes were just stopping me exceeding 20mph - it's a bit worrying when that happens.[/QUOTE]
Scrap the bike frame and get a disc braked version. The one occasion when you need to stop could be the death of you.
If you want more stopping power than Shimano fit Hope 4 pot calipers.
I think my biggest error is letting the pads get smooth before replacing them, once they are smooth they become useless in the wet.
may be not, but it's good to know I'm not the only one who struggles with braking in poor conditions. one run last week I was coming down a hill in wet slushy conditions and at best the brakes were just stopping me exceeding 20mph - it's a bit worrying when that happens.[/QUOTE]
Scrap the bike frame and get a disc braked version. The one occasion when you need to stop could be the death of you.
If you want more stopping power than Shimano fit Hope 4 pot calipers.
Yellow Saddle
Guru
- Location
- Loch side.
[QUOTE 5529136, member: 9609"]Would the leading edge of a longer pad not be more likely to dry the rim so the trailing end of the pad could get a better grip ?
I think my biggest error is letting the pads get smooth before replacing them, once they are smooth they become useless in the wet.
may be not, but it's good to know I'm not the only one who struggles with braking in poor conditions. one run last week I was coming down a hill in wet slushy conditions and at best the brakes were just stopping me exceeding 20mph - it's a bit worrying when that happens.[/QUOTE]
It isn't the leading edge that dries the rim, it is heat generated by friction.
No matter how well you wipe water off a smooth surface, a single molecular layer of the water/fluid always remains. This is called a boundary layer and it is holding onto the surface incredibly well. Nothing can wipe it off. The bond is formed through a temporary dipole that attracts the two adjacent molecules of different materials. An excellent example of this tenacious layer is water on glass. No matter how new and sharp your rubber squeegee, a single wipe always leaves a layer of water, albeit thin. This layer clings like hell. A second wipe demonstrates to you that it won't budge, because the squeegee judders and shakes over it. The lubricating second layer is gone, yet the boundary layer remains. It only disappears through evaporation. Wipe your bathroom mirror with a squeegee and see this in action.
Now the same happens with brakes. Nothing wipes the boundary layer, only the adjacent and fluid layers wipe off. The rim now has to heat up before the next layer disappears. This heating happens thanks to the friction between rubber and aluminium. The friction is particularly high between those two materials and the heat generated substantial enough to melt rubber. However, the heat dissipates very quickly and basically just "appears" between pad and rim, elsewhere it quickly disappears, so that even a hot rim is not as hot as just underneath the pad during braking.
In slushy conditions the rim obviously remains cold and further, any friction that is created is negated by the constant supply of icy water around and even on the rim. Slush and snow are particularly bad because it settles on the rim and supplies a steady trickle of lubrication to the rim.
The smoothness of the pad is irrelevant. the round nose of the pad is more important than fake fins and ribs on the braking surface. But like I emphasise, even a sharp, slick, new squeegee cannot do the job of a perfect wipe on a perfectly smooth surface. I think your observation of pad smoothness was skewed by something else, perhaps just observational bias.
Stay out of slush if you can't brake in slush.
Disc brakes obviously avoids some of the contributors to the problem.
I think my biggest error is letting the pads get smooth before replacing them, once they are smooth they become useless in the wet.
may be not, but it's good to know I'm not the only one who struggles with braking in poor conditions. one run last week I was coming down a hill in wet slushy conditions and at best the brakes were just stopping me exceeding 20mph - it's a bit worrying when that happens.[/QUOTE]
It isn't the leading edge that dries the rim, it is heat generated by friction.
No matter how well you wipe water off a smooth surface, a single molecular layer of the water/fluid always remains. This is called a boundary layer and it is holding onto the surface incredibly well. Nothing can wipe it off. The bond is formed through a temporary dipole that attracts the two adjacent molecules of different materials. An excellent example of this tenacious layer is water on glass. No matter how new and sharp your rubber squeegee, a single wipe always leaves a layer of water, albeit thin. This layer clings like hell. A second wipe demonstrates to you that it won't budge, because the squeegee judders and shakes over it. The lubricating second layer is gone, yet the boundary layer remains. It only disappears through evaporation. Wipe your bathroom mirror with a squeegee and see this in action.
Now the same happens with brakes. Nothing wipes the boundary layer, only the adjacent and fluid layers wipe off. The rim now has to heat up before the next layer disappears. This heating happens thanks to the friction between rubber and aluminium. The friction is particularly high between those two materials and the heat generated substantial enough to melt rubber. However, the heat dissipates very quickly and basically just "appears" between pad and rim, elsewhere it quickly disappears, so that even a hot rim is not as hot as just underneath the pad during braking.
In slushy conditions the rim obviously remains cold and further, any friction that is created is negated by the constant supply of icy water around and even on the rim. Slush and snow are particularly bad because it settles on the rim and supplies a steady trickle of lubrication to the rim.
The smoothness of the pad is irrelevant. the round nose of the pad is more important than fake fins and ribs on the braking surface. But like I emphasise, even a sharp, slick, new squeegee cannot do the job of a perfect wipe on a perfectly smooth surface. I think your observation of pad smoothness was skewed by something else, perhaps just observational bias.
Stay out of slush if you can't brake in slush.
Disc brakes obviously avoids some of the contributors to the problem.
- Location
- Somewhere wet & hilly in NW England.
I had a look at this which is about my level:
(At least on a cold, wet Cumbrian morning whiling away the day over coffee.)https://www.ducksters.com/science/friction.php
So, genuine question as I'm still mystified as to why size doesn't matter! (If I'd known that years ago it would have stopped a lot of my male angst...
)If size doesn't matter why do manufacturers not make calipers/pads smaller especially for those riders where a few grams saved is critical?
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
Clean your bike and get better pads as has been said. Regularly cleaned wheels only need soap and water !
I had a look at this which is about my level:
https://www.ducksters.com/science/friction.php
So, genuine question as I'm still mystified as to why size doesn't matter! (If I'd known that years ago it would have stopped a lot of my male angst...
If size doesn't matter why do manufacturers not make calipers/pads smaller especially for those riders where a few grams saved is critical?
In my attempt at laymans terms
If you increase the size then the pressure per sq cm will decrease proportionally. The only way bigger pads would help would be if you also increased the power (pressure) of the caliper. If you make the pad smaller, then you will wear the pad out faster which I guess would be a problem on a long alpine descent. It may be ok on a flat straight TT, but then again, why bother with a brake at all, just shove your foot on the tyre and pray.
MontyVeda
a short-tempered ill-controlled small-minded troll
- Location
- Lancaster... the little city.
My rim cleaning routine is shockingly poor, yet i don't have a problem with my brakes working in the wet (90s MTB calipers), but i do tend to start feathering at the top of a descent and control my speed all the way down.
