[Closed] Road Bike Braking On Steep Hills. Fast and Hard or Long and Slow?

Edit: that didn't go well

Edit Edit: hard braking then coast. You need to gain confidence in exactly how quickly you can stop

You haven't experienced proper road biking until you've got a wobble going on at around 50mph.. Stay off the brakes and just grip the top tube with your knees or check recent footage of froome for additional downhill mph..

Getting up to 50 is pretty normal on a couple of hills round here but thankfully I have never had to worry about stopping or had much wobble. This was so much different to anything I have ridden up or down before though.
I cant wait to do it again.

Stay off the brakes, stay loose, and bunny hop the drainage gullys 🙂

Oh and don't crash, it'll really hurt.

Was just under 50mph coming down Duncton Hill this week. I was trying to keep braking steadily though but still found the corner at the bottom bloody scary with traffic coming quickly the other way!

I would suggest that steady braking is the better method of control?

Discs not an issue.

I regularly pedal against my disc brakes on long steep hills to maintain my power zone on training rides. With a modicum of common sense it's absolutely fine.

If I know the descent well I'll brake when I need to (and only as hard as I need to), if I don't know it well (and don't have good visibility of what's coming) I'll drag a bit to keep speed in check then brake more as needed. In your situation if I knew it well I'd probably not be braking (and hopping the gullies) until near the bottom then brake as much as I needed to stop in good time for the gate. If bunny-hopping wasn't an option I'd probably just coast and brake hard before each one.

Brake hard and occasionally; gets the rim to a higher temperature than slow and steady. The greater temp' differential between the rim and air, when you release the brake, will mean it cools quicker during the off-brake periods.

Brake soft and constant; rim will not get as hot but the heat input will be constant. The cooling rate and heat input rate will equalise at some point and then your brakes will maintain a constant temp' until you release the brakes.

The truth is that it doesn't actually matter as you have the same amount of Kinetic Energy and Potential Energy to convert into heat. What matters is the volume of material in the braking surfaces; the rim and the pads. This plus the airflow and the rate of cooling afforded by the individual design of your brakes/bike will determine how hot it gets and how long it stays hot.

In other words; brake as you see fit - the only decisions that influence how hot everything gets have already been made by the brake and bike manufacturers*

* this assumes they do any analysis at all - which I doubt 🙂

One more thing; disc brakes contain less metal and hence will get hotter - however they will cool quicker.

You'd need to do the maths to figure it out 🙂

BUT it still comes down to;

the same amount of Kinetic Energy and Potential Energy to convert into heat

and

the volume of material in the braking surfaces; the [s]rim[/s] disc and the pads. This plus the airflow and the rate of cooling afforded by the individual design of your brakes/bike

Where is this hill? Sounds a great climb......

In the lakes only hardknott has sections >30%, and they are very brief. Managed to blow a tube descending Honister on Tuesday in the heat, should have lowered pressures and been more aware of rim heat, but just about avoided the wall of doom.

I regularly pedal against my disc brakes on long steep hills to maintain my power zone on training rides. With a modicum of common sense it's absolutely fine.

Roadies really are a breed apart. Pedalling uphill against your brakes !

As someone who is not comfortable at high speeds on a bike this braking / hills issue is another item on the list in the "against" column for road riding. As I have said before hitting a tree is no bargain at 30 mph but it certainly beats going under a car/lorry at a closing speed of 100mph

If you are worried why not go at a pace where one brake controls you. The other can be cooling. It does work.

jambalaya - Member
Roadies really are a breed apart. Pedalling uphill against your brakes !

Downhill.

I wasn't worried. I Just curious if there was an accepted best way to not cook the brakes.
Some of the above pretty much confirms what I thought that there is no right way only what you are comfortable with.

The road has no name (that i saw) its a service road over towards clee hill.

Next time I'm going flat out and see what happens. Nice knowing you all!

Roadies really are a breed apart. Pedalling uphill against your brakes

Downhill and I'm not a roadie!

David Arthur and Richard Hallett, back in the days when RCUK was reasonable rather than a pure press release site, did some basic research on a range of rims (alu, top end carbon and no name carbon) following David having a blowout while descending on a set of carbon rims (admittedly on an alpine mountain road of several kilometres). I can't find the article at the moment but they found that the risk with dragging on your brakes, especially if you have carbon rims, is the rim over heating leading to a blowout (less common on alu rims because they cool a lot quicker). The advice IIRC to brake hard and release just before coming to a complete halt with the final movement helping in the cooling.

Hard and late is my preferred normal method. Much more fun than dragging for the whole descent. Sometimes feels a bit out of control but all adds to the fun.

Downhill and I'm not a roadie!

Now I really am totally confused.

Short and hard, don't drag for any significant amount of time.
Once you get up >30mph you can get pretty good air braking by sitting up and sticking your knees and elbows out.

Also,
A) Eat less cakes - shouldn't be cooking your brakes to that extent on such a short descent unless you weigh as much as an HGV
B) Half a mile @ 30%+ didn't happen unless its on Strava

The truth is that it doesn't actually matter as you have the same amount of Kinetic Energy and Potential Energy to convert into heat.

Yes, but you have a choice of how you generate that heat: with friction in the brake or through air resistance.
By descending at higher speeds, you can lose more to air resistance, and less through braking. Of course, you'll get down quicker giving your brakes/rims less time to cool.

Just finished my road ride for today the last downhill is a good 3km of 8% so easily get to 70kph. I keep off the brakes until I need them then it's hard to scrub speed and off them as soon as possible for the corners. Saying that I definitely need to sort the back one as even on full pull the bike doesn't stop. Think the blocks are glazed.

Try riding a tandem for a few years, then you'll learn about rims overheating.

Two solutions are (1) to ride down slowly, all the potential energy goes into the brakes, but the power dissipation is low enough that it doesn't get too hot, or (2) go close to terminal velocity while sitting up in the wind, most of the potential energy goes into the air (wind resistance) though if you have to brake, the power dissipation may be very high. Obviously this approach is only viable when you have decent sight lines and no sharp bends.

Somewhere in the middle, where you are going reasonably fast but not enough for wind resistance to take over, you maximise your problems.

It doesn't really matter all that much whether you brake steadily or pulse on and off, the main issue is how fast you're descending overall.

Now I really am totally confused.

As part of training for XC I ride my mountain bike on the road to get longer periods of training at a specific power/HR intensity.

Freewheeling downhill is below that intensity so in order no to waste that time I pedal against my brakes.

Clear?

I went down a hill on my little clown bike brompton the other day. Strava says it peaked at 41.6mph, however accurate it is. It felt quite quick, certainly span out in 3rd gear

There's a 90 degree right part way down, thankfully I was given the heads up. I nailed the brakes and I have to say that it really wasn't keen on slowing down! Made it round the corner fine in the end, but the lack of power was a bit of a surprise - they're fine for normal pootling obviously

I think the road you're talking about is the old incline plane that comes off the back of Brown Clee hill. It's where the railway that brought down stone from the quarry at the top of the hill used to run. It's not a classified road but has a right of way and is paved. And I can vouch for it being that steep and long (and dead straight too). I've only ridden it on the mtb with disks though, wouldn't fancy it on a road bike.

@jakd95

That's the one. I was told by a mate that it would be unrideable so I had to go and find out.
Looking on strava this afternoon it the hill averages 20% but hits over 30% on the steep bit. So my initial comment about it averaging 30% was a bit out. Still steep as though!

This is the fastest descent near me [url= https://www.strava.com/segments/1225403 ]Crowcombe Descent[/url], nowhere near as steep as the OP's but fast all the same. I tend to stay off the brakes as long as possible and brake at the last minute but I feel much more confidant with disk brakes over rim brakes.

As part of training for XC I ride my mountain bike on the road to get longer periods of training at a specific power/HR intensity.

Freewheeling downhill is below that intensity so in order no to waste that time I pedal against my brakes.

Clear?

Made sense the first time for those of us into the whole training zone thing. Probably makes us seem like complete nutters to the other 95% 😆

Slow and steady keeps the rims cooler because you are spreading the dissapation of energy over a greater time.
There is also stuff to do with kinetic energy being half mv^[b]2[/b] and friction created on rims being proportiinal to their angular velocity which means when you are scrubbing off high speeds you are dumping heat into rim at a much higher rate than at lower speeds.

[quote=Dibbs ]This is the fastest descent near me Crowcombe Descent, nowhere near as steep as the OP's but fast all the same. I tend to stay off the brakes as long as possible and brake at the last minute but I feel much more confidant with disk brakes over rim brakes.

i guess you can always run out into the gravel pit...

i guess you can always run out into the gravel pit...

ouch!!! 😉 What tyres for an escape road?

Had nightmares about what I wrote above as it is a gross over simplification.

There are so many variables to factor in it is rather complicated.

Go really slow and steady will keep brakes cool (as speed ->0 temperature increase ->0), but on a steep slope going at a steady 30mph might be worse than modulating between 45mph->30mph by stabbing on the brakes because this in the latter you are using more air resistance to slow you down and stuff.

Standing up to increase air resistance will help, or getting a bit silly but large plastic carrier with handles over shoulders could make a handy parachute.

I really hadn't thought about braking, I've always just done it when I've needed to.

Never failed to work for me... Well apart from once when I didn't brake enough 😆

I wonder how the hundreds of thousands of folk riding mountains passes every month with 30km descents, switchbacks and 100m drop offs survive.

How do you know the brakes were outside safe operating temprature?

Mountain passes are rarely that steep.

How do you know the brakes were outside safe operating temprature?

I think this is a really interesting topic, one I pondered on the last tour.

Breaking on NZ roads on a [s]fully [/s] over loaded tourer was always a bit interesting*, I wondered the same thing.

Increased air resistance sounds like a reasonable analysis - if you drop a weight over a height you liberate "an energy". The more air resistance you thrown into the equation the less KE the brakes will have to dump. Assuming that in the braking period your rims don't overheat or your tyres blow, then dumping the KE into thermal suddenly at a point will be a smaller total.

I'm going with this approach in the future.

*XTR M970s on ceramic rims will stop you VERY fast...but how much heat can the wheel handle...?

Sorry thats BS, show me some evidence of brake failure, if brakes failed under that sort of use the manaufacturers would be out of business and getting taken to court.

Sounds more like a nervous rider with social media tourettes.

Mountain descents can be that steep, perhaps not the ones you'll see on the tour but even their combination of repeated corners and overall length will put as much strain on brakes and a hill in the UK.

Sounds more like a nervous rider with social media tourettes.

Who said anything about being nervous? Curious to know what is considered best practice yes. Nervous no. And we all have social media tourettes or we wouldn't be posting on here.

I suppose ultimately I want to go down this hill as fast as possible and want to know which way is less likely to kill me.

I actually think the plastic bag thing might be worth a try, it isn't going to be fast but it could be fun, a plastic bag doesn't take up much space in the back pocket. Anything that prolongs the life of brake pads and rims has to be good right?

[url= http://lovecycling.net/2016/05/diy-aero-ride/ ]Here is some inspiration[/url]

I remember making parashoot brakes as a kid. Works quite well.

Second brKing on a fully loaded tourer on a steep hill as fun. Melting pad smell!!! Lovely!!!!!!

I remember stopping a tandem with hope 4 pots on fairly rapidly from about 50mph (stoker's laces were wrapped around the pedal axle).

Quite smoky brakes after that. I don't know the solution btw, but on trails everyone says to MTFU and brake less so try that and let us know if you live.

Titterstone Incline?
I do find it hard to believe that there's a near 300m descent on a road in less than half a mile in the UK. (Yes, I know careful use of mixed measurements...)

I experienced overhearing brakes on my road discs for the first time today and had to use the run off escape chute! Whilst touring and carrying camping gear I was on the 25% descent down to Lynmouth. I was probably doing the worst of both approaches - light dragging with regular pulsing. The brakes faded and were preventing me gathering any more speed, but wouldn't bring me below about 10mph, and the front was smoking when I stopped.

Not experienced overheated road brakes, but did once experience an overheated front rim followed shortly by an exploding front tyre whilst braking hard at speed coming off the Col du Glandon. That was quite an experience.

For me braking hard to slow down when needed - partly 'cos I like the fun of going fast and partly because it reduces heat buildup. alternate brakes if you need / want to drag to give each brake chance to recover. At higher speeds the brakes cool quicker ( greater airflow) dragging brakes at slow speeds is the best way to overheat them

Keep cool. Do skids. Locking the wheel means the brakes don't generate any heat. Bingo.

I forgot to update this thread. I went back last Friday to try again. This time there was a new element added. It had rained. Getting up was one of the hardest things I have ever done on a bike. I had wheel spin on every pedal stroke probably loosing me quarter of every stroke. I made it to the top without stopping which I was very pleased with. Descending though was sketchy to say the least. The road has a thin layer of moss in places which when wet meant it was like riding on ice. Fast and hard braking didn’t work at all. Dragging and riding slow worked to a point but it didn’t take long for the burning rubber smell to appear. In the end it was a medium speed and swapping between front and rear brake that felt most efficient / safest although it was very easy to lock the front or rear on the mossy bits. It was great fun though and I can’t wait to do it again.
Interestingly a friend who won’t mind me saying is a terrible descender did it the next day on a disc giant defy and had no problem at all. He braked consistently the whole way down and didn’t suffer any fade.

I've been wondering about this too. Could you try each method of braking and use something like this to check temp of rim?
https://www.amazon.co.uk/BENETECH-Non-Contact-Infrared-Digital-Thermometer/dp/B007Q87J3U

My gf and I were touring in Cuba and had a scary descent from Topes de Collantes. They don't have nice 8-10% gradients like they do in the Alps! More like 30% for miles, and we were on loaded bikes. Just had to keep stopping.

More like 30% for miles,

REEEEEALY? 🙂

Looks like the average is mid-teens depending on what version of the climb/descent you look at

Don't drag your brakes unless you have a "drag brake". Brake hard to scrub speed, allow rims to cool and repeat.

The tandem has a proper drag brake designed for a moped with cooling fins. Not a light option 😉

REEEEEALY?

well it certainly felt like it 🙂

Don't drag your brakes unless you have a "drag brake". Brake hard to scrub speed, allow rims to cool and repeat.

This. Especially them fancy carbon rims. I saw plenty of riders in the Alps who had blown inner tubes due to overheating their rims from brake drag.