[Closed] Why am I such a soft **** on road bike descents

Tried a bike fit?

I was in a similar position coming from an MTB background regularly shuttling/DH runs but skinny tyres and being on the drops have me the fear.

Some minor tweaks to my handlebar setup with the help of my LBS had me finally feeling comfortable on the drops and I’m now getting silly speeds on the commute down the hill to work.

Ask Richie Porte.

I find relaxation helps. Wiggle the fingers as It’s too easy to grip the bars too hard. It’s also easy to imagine the consequences of a misjudged action!

Better to arrive at the bottom in one piece.

Tracy Hannah says singing helps on a mountain bike - try that !

I'm kinda similar, a totally pussy on descents on the road. However...

irrational fear

I wouldn't say it is this. Fall off an mtb and you might break a bone. Come off on a road descent and the consequences could be way way worse.

I'm happy to go at the speed I'm comfortable with, well within the limits of grip on the tyres. No one is paying me to ride my bike, so I just Poole down the hills.

I felt the same. My road bike has Corima deep carbon rims, rim brakes and the front has only 18 spokes. I'm 15 stone and I got the fear when descending fast and rising in dappled sunlight where potholes go invisible. A Conti GP4000 28 tyre won't fit in the fork so a 25 is the biggest I can go.
A few weeks ago I bought a cheap alloy rim front wheel. A travesty, fitting this to a carbon Pinarello with Campag Record (and still the Corima rear) but it's without doubt the best upgrade I've made. I enjoy my rides much much more.

yep, much higher consequences and much less thrills/enjoyment on the descent to justify the risks.

A guy in the local group had to go wide on a downhill corner because there was unexpected gravel on the road, and hit a people carrier - 3 months in hospital and he was lucky...

I wouldn't worry to much, riding will increase confidence, get someone to look at your position, it's all about relaxing so if your are tense back off

I was always fast downhill, Then on a ride I wasn't pushing it, it was just a nice evening and I thought let's not waste it. I ran over a bit of metal at 40mph just going into the steepest twisty part of the descent, went straight from full tire to being on the rim in less than a second, barely held it up, missed the oncoming car, wobbled again and high sided at 30mph, just missed the barrier protecting the drop, and then used my body to slide to a stop. Fortunately the car behind was slowing and stopped.

I am now slow going downhill, changed the tire setup, and view the world differently, however confidence is coming back and it's not stopped me riding

Bike fit? To help with a mental block? Okey doke!
Sounds more like you need some meditation to convince yourself you won’t crash. I had an off a couple of years back (on the flat!) which slowed me right down. I guess you just have to be confident in your technique to relax and KNOW you’re not going to crash. Anyone you ride with give some tips?
Other wise, I’d say don’t worry about keeping up with anyone, crashing on the road can have nasty consequences, so let your mind keep you safe.

Tracy Hannah says singing helps

It’s about being relaxed, innit.

Maybe you’re the enlightened one? If one was designing a bike from scratch to safely, confidently and quickly do road descents then it wouldn’t end up anything like a road bike!

Tracy Hannah says singing helps

It’s about being relaxed

A bit, but that’s more to make you concentrate on the words of the song, so you can’t overthink what’s happening in front of you, you just deal with it, almost sub-consciously.

Got a song you like OP?

I’d half consider fitting a dropper if my frame would take one, possibly with an under seat lever.

Maybe a slightly wider tyre?

I found that lifting my backside off the saddle and slightly resting an inner thigh against the top tube made me feel more solid and a bit more confident on road descents.

Group descents can be a bit bizarre too- maybe a couple of rides with someone who descends that sort of terrain comfortably, following their line, would help?

Find a nice long straight descent to ride down and get used to the speed. Something like Britwell Hill in the chilterns, easy speed, no corners and good sight lines.

Then go off and find something more technical!

Most stuff transfers from MTB'ing, experiment with stuff and see what works, the advantage of roads is the corners are generally consistent and longer so you can see what effect dropping a shoulder or over twisting tour hips has mid corner and if it works try it on the entry to the next one.

I think it’s probably best to have a bit of fear on the road bike as coming off at 40mph just dressed in Lycra is going to be messy.

I went out on my road bike either last year or earlier this one round near Bath and went down a huge hill. I knew I was going fast but on checking Strava I got to 48mph. That’s a bit scary and the consequences of messing that up would be awful. SO I’m trying to dial back top speed a bit when on the road bike now.

You can get road coaching for descending I’d have thought - it you want to improve descending technique I’d consider that. I lost a bit of confidence cornering off road after a couple of biggish crashes and 3 hours of coaching helped.

I find fast road descents far more challenging than black MTB descents - the speeds are a lot higher as are the consequences. A couple of things that got me from a 30-40mph to a 40-50mph descender are technique and practice. Technique: get in the drops. Yes your speed goes up because you're lower but the braking is much easier than being on the hoods. Brake hard before a corner not during. Use your weight, put it through the outside pedal. Look around the corner as your enter to see where you want to go.
And practice: in the UK we tend to have pretty short descents. It really helps to ride 20-30km descents (ie the Alps, Pyrenees, even a few in Australia) and just get in the rhythm of it and get confident in the grip of the tyres. I have a few fast descents I love (generally flowing 7-8% like Burdincurutcheta) and few I hate (10-12% straight down like Lake Mountain) but you definitely get faster the more you ride them.

Bike fit? To help with a mental block? Okey doke!

Small changes in setup make a big difference in feel on a road bike. Feel influences how relaxed you are, just the same as the difference between different road bikes some inspire confidence some don't

But meditation, okey doke!

A longer stem helps improve confidence too.

It's not really irrational.

Your MTB is designed to let you put your body weight in the right place, to weight the wheels according to the descent you're on. On a road bike, you're on the drops, you aren't really moving around all that much. Your weight is centred or on steep stuff over the front, so if that washes out you're toast. As a competent MTBer you're probably acutely aware of this (I know I am). A riding position that feels good for getting the power down on the drops on flat bits might leave you too far forward. It does on my bike - but I think the frame is a bit too small. The bike fit idea is a good one potentially - if the bike doesn't fit, the weight distribution could be wrong which will affect your cornering confidence hugely.

Then there's the physics. On a fast singletrack off-road descent you might be doing 15mph; on a road it could be 45mph. That means you're carrying NINE time more energy. So if you come off it's potentially far worse.

Watch & learn
https://m.youtube.com/watch?v=RxXqQqAc2pA
Seriously, on the road you have to ride within your limits. Confidence really is just about practice, but on the road you simply can not afford to ride at 100%. Just keep riding and at some point you will speed up.

You need to try and convince your brain to let you go faster than 45kph on long, straight descents. It'll hurt lots whether you crash on tarmac at 45kph or 65kph so I find it best not to worry

Try riding on your own and not having the pressure of trying to keep up with the people in your club? The pressure of trying to do that probably leads you to tense up and if you do that on a bike things don't work as well.

I had a front-wheel blowout at speed descending off the Col du Glandon a few years ago during the Marmotte. I was over 110kg at the time, and this coupled with heavy braking on rim brakes, altitude and high tyre pressure resulted in the rim overheating and causing the tube to let go.
I managed to stop it unscathed (other than a completely destroyed GP4000), but ever since I've had a mental block about heavy braking on road descents, like I'm always afraid it'll happen again. I'm picking up a disc braked road bike today actually, so hopefully problem solved.

I ride my road bike in North Lakes mainly (so Whinatter,Newlands, Honister etc).
Biggest difference for was to fit a set of slightly flared wider bars (think Salsa Bell Lap or Ritchey Evo Maxtype flair). Not bike fit as such - just a way to feel more comfortably in control.
I'm normally well in the fastest 15% on any road descent (though definitely not the fastest!!!) so it works for me.

Used to regularly go over 50mph on descents when I first started road biking. Came off at around 30 on a gravelly corner about 4 years ago, which was extremely painful. I've never really got my balls back properly after that - rarely going much over 40 now. Did the Etape Du Dales with a couple of mates back in May and resigned myself to being the last at the bottom of the descents (although not really by that much). Could always catch them on the flat afterwards though.

Also don't trust strava leaderboards.

I came down Pishill the other day, took 13minutes from the top to the junction, averaged 26mph, and that was off the brakes down to stone and then pretty much team time trialing it with another rider, going faster would be a massive effort, certainly I won't beat that time solo any time soon.

The strava record is 35mph, I'm pretty sure that's because it's a time trial route too (and obviously there are some very fast clubs about who'll be faster than just the two of us).

Also - who cares? Road biking is about one of two things: fitness, the feeling of pushing your body physically and zipping along; or it's about getting out in the countryside covering distance. Descending thrills are for the MTB surely?

Nope. I really enjoy a good road descent. It can be pretty exhilarating.

Yeah, I can get just as much pleasure from a long road descent as a mtb one. Terrifying but very exhilarating.

people do also race, go for times, and generally like to push themselves. I'd echo points about learning some technique - it's not just about nerve.

I’m the same.  There’s a series 3 lumps in Herts starting on a down ward slope.  If you keep peddling gravity has you speeding over the rollers and halfway up the last climb.  Stay on the gas and I’m 20s to a strava kom because for some reason I carry speed well.  BUT I cant help but imagine a car pulling out of one of the many driveways along the road, it really holds me back - I’d be doing 70kph on the first downslope if I go hard enough, imagine the mess....

Descending thrills are for the MTB surely?

Nah, I get at least as much pleasure from nailing a road descent. Everyone is different though. Fancy a proper crack on this descent, got within 20secs of the KOM on my first time down there so should be able to get closer now I know which way the road goes. 12% average gradient, twisty and dry stone walls. What could possibly go wrong? 🙂

https://www.strava.com/segments/4983287?filter=overall

https://veloviewer.com/segments/4983287

I’m the same. I’m much faster descending on road on a mtb than a road bike. Road bikes just feel like death traps. Then I added 20lbs of bikepacking gear and it descended absolutely fine.

Learn to ride a motorcycle. Then the road bike feels slow.

tbh, i don't really have the balls to go much over 40mph/64kph on the road. regularly touch that, but it's just the extreme end of comfortable for me. Any faster starts to become the light end of terrifying for me and I just don't feel in control so will temper the speed.

You do have to give massive respect to the roadies that regularly descend at speed above 80+kph/50+mph.

It's all just about finding your comfort levels isn't it. Road surface also has a massive part to play, obviously much easier to go faster on smoother roads and feel more comfortable.

And he could wear the leathers on the road bike too.

Come off on a road descent and the consequences could be way way worse.

Really ? Fall off on a road bike decent at 30+ and you tend to get gravel rash. Fall of on an mtb at 10mph and you break bones.

Having said that I’ve had road bikes that inspire no confidence downhill, never twitchy but just don’t want to turn or inspire confidence in the corners

The other thing I find helpful is just being rational - what are the things that could cause a crash (gravel, a pothole, a cow, a crosswind wobble etc) and how do I avoid them. If there's no good reason that I'd come off, and especially if I know the road, then it's easier, logical even, to stay off the brakes. And then I get overtaken by bunch of riders.

British descents are some of the worst out there. Often "variable" road surfaces, often blind corners, junctions, traffic, narrow, relatively steep etc - you actually need to keep your speed in check a lot of the time rather than actively caning it. Yes there are plenty of exceptions but there's always that doubt in the back of your mind.

Learning to relax on descents, it really helps to do much longer smoother ones. Spain, France etc where you can really get into the flow of it. In the UK, you've only just got into the feel of it when you're suddenly out the bottom.

The key to it is relaxing, dropping your shoulder and pushing the inside bar down/forwards.

 The list of things that make me slow down are:
It being steep
Tight bends
Signs telling me it’s steep
Loose gravel
Crap road surfaces
Not knowing what the road layout is
No barriers at the side of the road
Drops at the side of the road
Bushes at the side of the road
Traffic

All pretty sensible reasons to slow down a bit. But if your getting dropped by club mates your probably being a bit over cautious.
Relax and trust your bike, over time familiarity will increase your confidence. And as said get into the drops and get low, you'll feel much more stable and in control.

Are you in the drops? Safer, your hands won't slip off and more stable - lower centre of gravity.
Find a well surfaced decent and practice, good excuse for a holiday in the Alps / Dolomite's!

What sort of bike do you have? Does it fit properly?

Get yourself out to Majorca for a week and you’ll soon get into the swing of it! Having good, long roads to practise on makes all the difference.

The graveyard is full of heroes.

I have far too much imagination and experience to go too fast on a descent.

A sudden stop from 55kph thanks to a car stopped in the road around a blind bend and a front wheel washout at 65kph thanks to oil on the road means I don’t really go fast anymore.

tbh, i don’t really have the balls to go much over 40mph/64kph on the road. regularly touch that, but it’s just the extreme end of comfortable for me. Any faster starts to become the light end of terrifying for me and I just don’t feel in control so will temper the speed.

You do have to give massive respect to the roadies that regularly descend at speed above 80+kph/50+mph.

I honestly depends on the type of decent as much as anything, there's some I wouldn't want to haul down, but have also seen over 100kph on the right piece of road on the continent, with caliper brakes and 23c tyres too!

it's interesting. I got took out doing 40mph by a car pulling across me. Broken spine, very very very lucky to be walking. Life will never be the same and I'm stuck with pain every day for the rest of my life. But do I go much slower on downhills now? Well yes, maybe. But I still hit 35+ and upper 20's off road on the cx bike. Guess I am just reckless, but I've always felt totally in control descending fast. Which makes the accident and the fact I had no chance all the harder to take.

Look up, relax, think 3 steps ahead. If you've got 20/20 vision everything should be ok. Except the one time it isn't.

It always bugs me when I read about folk breaking 50mph, it's been a glass ceiling for me for years, might have broken it in the Alps but my computer was fried.

How do people do it, is it a weight thing, or are you spinning out a 53/11?

I felt immediately comfortable on a road bike, but from day one was always trying to emulate the pros e.g. on the drops, low over the bars, racing lines, always trying to lean the bike etc. etc.

Maybe if you just practice trying to look right the rest comes naturally! 😉

How do people do it, is it a weight thing, or are you spinning out a 53/11?

It is mainly down to the hill.

It always bugs me when I read about folk breaking 50mph, it’s been a glass ceiling for me for years, might have broken it in the Alps but my computer was fried.

How do people do it, is it a weight thing, or are you spinning out a 53/11?

You need the right descent and conditions.
I can hit 40mh on almost every road ride I do (living on the edge of the Peak District is helpful for thing like that!).

To go much over that you need longer steeper hills with good sightlines, good road surface, minimal wind (or a straight tailwind) and other favourable conditions (like minimal traffic). There's a few places I know I can aim for 50+ mph but I'll bail at the slightest hint of there being anything wrong.

Fastest I've ever been was on the descent of the Grosglockner Pass towards Zell am See which was 66mph. That was ****ing terrifying but exhilarating at the same time. I didn't dare do anything to upset the aerodynamics, the bike stability and the braking and body movements had to be so gentle to bring it down to a more controllable 45 or so. I've had 60+ on two occasions before that, once in the Alps and once in the Trough of Bowland on a long straight with a tailwind which required a lot of effort to bring it down to a more manageable speed before the road turned right and the wind became a crosswind. As it did so it blew me right to the very outer edge of the road.

Cheers for the responses. I’m in the drops on descents and my bike fit is spot on. I’ve had two proper bike fits over the last couple of years and they have made a difference; 44cm bars and the general bike fit itself definitely improved confidence BUT I’m not happy and I feel I’m holding back.

I guess I’ll just keep at it and try and relax a bit more.

@13thfloormonk

Try the descent from redstone rig down to whiteadder

After the turning just gradually spin up through the gears (it's fairly flat at the beginning) then when the gradient increases spin the cranks up to a bit over 45mph and just tuck.
It's doable in 50x12.

I don't wear a helmet though. Maybe that's what's holding you back 😉

Not got time to read whole thread so apologies if repeating others' ideas - but two points...

- Try dropping your stem by 5mm or 10mm, might improve front-end grip and make for more confidence.

- Are you on harsh-feeling wheels? Being able to feel every bit of grit on the road through my old Ksyriums used to make me nervous over about 50kph. Now I'm on RS81s with a much smoother feel and as a result I am more relaxed and happy to stay off the brakes to 60-plus.

Learn to ride a motorcycle. Then the road bike feels slow.

Cheers, we actually dropped the stem at my last bike fit, which does feel better.

I’m on Hope 20 Five wheels with 28mm tubeless Schwalbe Pro Ones is nothing particularly harsh in the wheel and tyre department.

Have a look at tyre deformation tables. At 90 kg I couldn’t get the necessary pressure for 28s without going over the maximum pressure rating for the tyre.

I can hit 40mh on almost every road ride I do (living on the edge of the Peak District is helpful for thing like that!).

Yeah, I regularly top 60kph on my commute 🙂

There’s a few places I know I can aim for 50+ mph but I’ll bail at the slightest hint of there being anything wrong.

I need to explore a bit more as I've been topping out a bit over 70kph on local descents since moving to Macc. Maybe I should ride down The Brickworks rather than ride up it? Freewheeling down Newlands on the Fred Whitton I hit 83kph - shame I was saving my legs for all of the climbing!

Have a look at tyre deformation tables. At 90 kg I couldn’t get the necessary pressure for 28s without going over the maximum pressure rating for the tyre

What?

90kg isn't heavy, you shouldn't need to be anywhere near max pressures on 28mm tyres.

Look into road craft for motorbikes , you can use some of the information to help you guage how fast to go round a corner .
Use you head more than your hands . Flying down mountains is all about vision, then hip steering , footwork , and to some extent counter steering .
Make sure the bike is proper cranked over , heel down , pressure on insdie hand
Get 95% ish of the braking done before the corner. Be positive on the brakes, put them on and keep on applying pressure. IMO short and firm is better than long and draggy , gives things more time to heat up.
Be off the front brake before turn. Look and register the turn in point then ignore it your brain will record and do the calcs for you , look through and out the corner from then on
If you feel you have gone in 5mph too hot then feather the back brake ( others may disagree but thats fine) to scrub off speed , but do not panic.
Go in 10mph too hot and then its more luck than judjement buut using all the above with more lean angle, more torso twist , and good eye work might just save you.
Good dependable tyres help too. I use Michelin Pro4 service course which give a good mix of longevity V grip for 200gm tyres

Seems like motorcycling experience may add a bit of confidence, once you've been 150mph on two wheels, 50mph doesn't seem that fast 🤔 love road descending myself

For just over two years, I've loved climbing the cat3/4 hills around Butser Hill, but there are very few descents I will not be regularly scrubbing off speed with the hydraulic brakes on my road bike.

A number of factors off the top of my head...
My RTA ~5.5 years ago, trying to make a jigsaw using my upper jaw and teeth.
Many of the South Downs roads/lanes I use are not in great condition, rain often brings new stones on to the tarmac, strong winds can often knock hefty branches onto the road etc.
Lots of barmy pheasants around who have absolutely no roadcraft, plus I've had deer and squirrels shoot across the road in front of me.
Blind bends and mostly narrow lanes, plus some quality driving by motor vehicles.
Had a lucky escape during late summer 2017, while still riding the default 25mm Grand Sport Race tyres, I understeered down a fairly steep sweeping downhill right bend near the Sustainability Centre and only just missed a tree trunk as I veered into the hedge and fell on to my left side.

About the only descents I'll happily not touch the brakes on are wide, mostly straight ones:-
Beacon Hill Lane https://www.strava.com/segments/3467265
Sheep Pond Lane https://www.strava.com/segments/4555381
And my favourite, Mercury to Oxenbourne https://www.strava.com/segments/15769432

How do people do it, is it a weight thing, or are you spinning out a 53/11?

As said above it’s more about the right hill and conditions.

This decent in Otley I have been over 62mph. It involves having a wind behind you, a clear road and pedalling as hard as you can at the top before you run out of gears.

You can even get around the bend at the bottom without braking as even sitting up is enough to slow you from the 60’s to 40’s mph.

Over about late 40’s you wouldn’t want to be pedalling.

I haven’t achieved 60+ on it for some time though as the condition of the road has deteriorated.

https://veloviewer.com/segment/1795722

Of course alpine descents tend to be different to UK decents. There are very few UK roads that allow speeds of 50mph + and repeated slowing for bends and repeat

I’d say that it’s a lot to do with becoming older and wiser. You more than likely don’t want to go through another recuperation period ‘if’ you come off and maybe subconsciously or consciously your personal and financial responsibilities are of a higher priority now?

I get the fears of a front wheel wash out, or a car pulling out or on the wrong side of the road, or stopped, or an animal appearing from the hedgerow, I call it my strong sense of survival! Risk assessment.

Wisdom is a virtue, it’s one of the major benefits of progressing through life and applying knowledge and experience 😁

If you really want to stay with your mates downhill, hypnotherapy.

How do people do it, is it a weight thing, or are you spinning out a 53/11?

Like I said before, road and conditions. I'm 85kg but on a north of 10% gradient, with an aero tuck, you're soon up to speed. You can't pedal at that speed without massive gears. You do however need to be confident in your kit and tyres, and that you can see a long way down the road as things come at you quickly over 100kph.

There is also risk, which you may or may not be comfortable with. I had a big crash on the Stelvio a few years ago due to a rear tyre blowout at 50mph!

I raced at Elite level for 15 years so a bit of speed doesn't worry me much. I do also ride motorbikes.

Have a look at tyre deformation tables. At 90 kg I couldn’t get the necessary pressure for 28s without going over the maximum pressure rating for the tyre.

You're doing something wrong there I'm sure. Got a link to whatever table you're using?

And they're always a compromise, there's not one magic pressure. Most tables dont have anywhere near enough difference front-rear to get the same contact patch because half the pressure in the front would feel horrible.

Most show the load on the wheel, so at 90kg you should be looking at the ~30kg and ~60kg numbers which would be the first obvious mistake!

It the prospect of being blindsided by a pheasant which plays on my mind, after hearing that this happened to a pal's clubmate.

It the prospect of being blindsided by a pheasant 

I love a road downhill, but its the Sheep around here that get me worried 😟😟😟

It's not irrational.

Any accident you have at motorbike speeds in cycling gear isn't going to be pretty.

Practise emergency stops and ride within those limits, but generally trust the bike.

And do not go any faster than the speed at which you would be happy breaking really hard at
What are you going to do if you exceed
that point then. Not brake, put a foot out, pray,

And me obvious point. There is a world of difference between descending a closed road safe in the knowledge that nothing will be coming the other way, and a typical road with possible cars that my have no idea of the likely hazards that may befall then.

Just take it easy, relax the arms and enjoy it. Says he who’s aerobars came loose descending the welsh gift hill at 79 km/hr in a TT. At least it is a straight dual carriageway.

There is a world of difference between descending a closed road...and a typical road with possible cars

This 100%. Especially when dozy drivers can turn across your path when you're doing ~40 mph. Trust me it hurts. Downhill Strava KOMs on the road are for nutters in my book.

Some bikes are just better downhill, my Diverge, which is a gravel bike, with slicks on sees me at the front on group descents. My carbon roadbike is faster on the flat and up hill but shit downhill and sees me at the back of the same group ride.

Basically in my head I’m imagining all sorts of terrible stuff happening, so slow right down. This means on really steep descents I’m at an absolute crawl, watching my club shoot off down the hill. On one, maybe 15%+ twisty descent in the Yorkshire Dales I was absolutely terrified.

Well, beyond all the stuff about bike fit, tyre pressures etc, it sounds like you mostly have a very pessimistic take on acceptable risk where you're thinking more about consequences than the likelihood of something actually happening.

It's an interesting one. Fear is what keeps us alive. If your ability to assess the confluence between what you're capable of doing and what you're trying to do is faulty, stuff goes badly wrong. You see it with climbers - Joe Simpson is arguably a classic - where they have an unrealistic idea of what's an acceptable risk relative to their own capabilities.

Really good climbers - Leo Houlding's a good example based on folk I've spoken to who've worked with him - have a super accurate sense of where their limits are. That means they push quite close to them, but rarely go over the edge.

It sounds like you're at the other end of the continuum where you're so acutely aware of the risks involved, that it actively means you go far slower than you need to relative to your abilities. Probably.

I don't know how you get beyond that. I'm sure there are mental drills or strategies you could employ, but I'm not a sports psychologist. But it does sound like you're overwhelming your risk assessment system with negative data that's then inhibiting you. Your fear response / self preservation system arguably needs recalibrating. Too much logical brain.

One really simple tip is, if you feel like you're going too fast, look up and further ahead. It massively decreases the sensation of speed. Everything seems to slow down.

That would be my take anyway. You're thinking too hard, but you're also thinking too hard about the wrong things.

You’re not the only one that’s a chicken on descending, I am too. I can tell when going 30mph as my fingers start pressing the brake levers.

I’d love to be able to break 60kph but my brain kicks in with self preservation.

I always ask myself, why do motorcyclists wear leathers and we wear Lycra yet we can do the same speeds?

Road rash hurts kids!!

I found my downhill speeds increased after I balanced the wheels of my road bike.
https://www.sigmasports.com/item/Silca/Speed-Balance-Kit/DRZ2

Before, my bike with 50mm rims and long heavy valve stems always felt increasingly unhappy over 50 km/h. I rode an identical bike with shallow rims and short valve stems and it felt much calmer, a feeling I now have with the balance weights installed.

Having said that I’m still careful about where I really let the bike go. Long sections with good visibility only, and watch carefully for gaps in hedges etc that could cause a sideways gust.

I like this guy’s write up of how to descend.

http://flammerouge.je/factsheets/doidescend.htm

As BWD says, its a mental thing you've got yourself into.

I'd go somewhere with a decent variety of nice hills - smooth, relatively light on traffic, good sightlines* - and just work on relaxing, looking up, feeling the bike flow under you and just work up gradually. Freewheeeling at first then a few pedal strokes in the straight bits, then building the speed gradually and then working up to sharper bends or steeper sections.

If possible, follow a good roadie down just to see their lines, the way they're leaning the bike etc. Also, following someone means you're looking up rather than at your own front wheel.

*it may be that these hills are best found in Spain!

I practice the same techniques that Tony teaches on the MTB on the road bike.

Get used to leaning the bike and pushing the bars down to turn and you will get more comfortable with the descent speed and how to speed up and slow down.

I built up my confidence over the years and hit 59.1MPH on the way into Brighton on the L2B a couple of years back.

Remember that an uneven weight distribution will make one end unsettled.

Remember the coaching.

I'm the opposite, was very good on road descending, and not great on MTB.

I've given up road riding due to serious injuries, so my MTB descending is getting better, slowly !

Just relax on a road bike, don't death grip. You've got to pick the right hill to get a good speed up (e.g. no side roads, bends, good surface). I used to regularly hit 50 mph and have done 60mph in North Wales, and this is on a 90's vintage steel bike (OK Columbus SLX and Dura Ace) and 23mm tyres.

Really ? Fall off on a road bike decent at 30+ and you tend to get gravel rash. Fall of on an mtb at 10mph and you break bones.

Hmm just like Chris Froome

didn't

and allegedly he's pretty good on a bike.

From the OP it's clear it's a lack of confidence.

You're talking about skinny tyres, needing disc brakes, and getting worried on a straight road at ~30mph.

A decent set of slicks will grip a road better than most MTB tyres.
30mph isn't fast at all on a road bike.
You don't need disc brakes (although I'll accept they're probably sensible if your confidence isn't high and you ride in all weathers).

Basically you're thinking like a mountain biker, but you're riding on the road. In the dry you just need to get used to being off the brakes at least on straights, and brake before corners then off the brakes and you'll be surprised how hard you can lean over. Obviously if you grab a handful of brake halfway round a corner you'll give yourself a scare, you're asking the tyres to do 2 things (there is a bit of a grey area if the road really is steep, you would have to enter some tight steep corners incredibly slow otherwise!).

As other people have said though, it's not necessarily irrational, get up to 50mph and have an off and it's going to seriously hurt, whereas most of the time a fall on an MTB has little consequence. Even at 30 it'll hurt. Just make sure it doesn't happen.