Question for the maths gurus amongst you.
If I was going to climb a hill that had a gradient of 25%, and I was going to be using a 34-32 Gear, what gear ratio would I need to use to simulate that kind of effort on a 9% hill - power would be the same, I'm referring to simulating the cadence and torque required.
[img] 
[/img]
34-11, if I understand the question correctly.
34-11, if I understand the question correctly
I'm not even sure understand the question! But that sounds about right I reckon...ie, I'd have to be out the saddle grinding away to get up a 9% in that gear
if you want simulate a hill 2.5 times steeper what you need to do is climb 2.5 times faster and in a gear 2.5 times higher
4
Could you put a treadmill on the hill?
As tj says you can replicate it by speed. Using the calculator below it appears if I've used it right you go from 6.7kph to 17kph.
http://bikecalculator.com/veloMetric.html
A grade of 25% is 2.78 times as steep as a 9% grade. Assuming that gravity greatly outweighs rolling resistance and air resistance, a similar effort (i.e. same vertical climbing speed) will require gearing 2.78 times higher. With the same 34 tooth chainring, you need to divide the 32 tooth sprocket by 2.78, which gives 11.51. So an 11 or 12 tooth sprocket. This will give you the same vertical speed for the same power output and cadence, but 2.78 times the road speed.
That’s Wangernumb!
But you won't be simulating the slow-down between pedal strokes. You could achieve that by adding friction, sort of.
Maybe a 16 inch wheel on the back to steepen the effective hill?!
As tj says you can replicate it by speed. Using the calculator below it appears if I’ve used it right you go from 6.7kph to 17kph.
I'd kill to be able to do 6.7kph on a 25% hill!
I’d kill to be able to do 6.7kph on a 25% hill!
It seemed to suggest 390w with a 70kg rider !! So you and me both 😟
It seemed to suggest 390w with a 70kg rider !! So you and me both 😟
And I'm 90(and a bit)kg 🤣
6.7kph on a 25% hill
Which is VAM of 1675 Vm/h, which is pro roadie level.
I'd reckon getting up a proper 25% slope, not just a short ramp would be a massive effort for an amateur rider on a road bike with normal road gearing.
Do the training hill and the big hill have steady slopes of 9% and 25% respectively?
These two inclines are right on my doorstep...
https://www.strava.com/segments/19974352
https://www.strava.com/segments/19814823
The top one ramps up massively in the second half to ~20%, the lower one is more steady. To roughly equal 34/32 up Dell Rd (the nasty one), I'd say something like 34/22 up the other.
Why not add weight to the bike?
Then your cadence can be similar to that required.
Or maybe you need a singlespeed in your life....
Ratios are irrelevant. Power is everything, work out the wattage for your weight at that speed and then work out the speed on the lesser incline for the same power. Just match the power. 😁
I did a 9 speed high range conversion(sunrace 11-40t with road link).. And on small climbs 50-40.. Works great bit of resistance but is similar to 34-40 on really!!! Steep stuff..
I find it candence is similar then and can pic and choose how much grinding or spinning I do on said hill.
Tie a car tyre to the back of your bike and drag it up
I find it candence is similar then and can pic and choose how much grinding or spinning I do on said hill.
I presume the issue is more that whilst one can choose sit and spin at x watts on a less steep hill on a 25% one you're simply 'getting up it', therefore trying to replicate the lowest gear you'll have and the actual effort you'll have to muster, not just the power you'll need to output, for which you could choose a descent and sprint down it. Wouldn't make great preparation though.
As already said for the simulation to be effective you have to also try and simulate the low speed and 'pulsing' effect when you are using body weight as well as leg strength to get the pedals over the top of the stroke when on hills that steep. Going two and a bit times faster up a hill two and bit times shallower (with the same power and cadence) does not really cut it. Again, I'd be throwing a load of weight at the situation - a tow rope to a rider freewheeling behind you maybe.
I'd practise pushing the bike up the stairs.`:-)
50-40 feels like 34-40 but feels similar bar a small candence difference
No power meter(not like I could fit one anyway--rocking sqr-tpr still)
But I can get up x hill at x speed on either but x+ a bit of effort is 50-40 and x- a big of effort(+a little spinning) is 34-40
The bike is about 20kg loaded.. So weight definitely makes hills more challenging..
An interesting question and one which I've considered in a different guise - is there any point I weighted training.
My conclusion (to my question) was in general no. My reasoning was that inevitably you choose the optimal gearing for the conditions so when I was by myself it was counter productive as I was simply practicing going slower.
However, two scenarios where it had a positive training effect was when I was forced to keep pace (with someone else) and secondly your situation.
Rather than specify gearing because this is personal it might be better to focus on the training you need to do for steep climbs and you will find your own answer. I would suggest that on a 25% with 20kg load you will be in your highest (or lowest, I can never remember) gear (34/32) and turning a cadence of about 40-50. So to simulate this on a lesser climb (and build the muscular endurance to cope) drop down the cassette until you can only turn the pedals at that cadence. You might also train both seated and standing but recognise that you may not be able to remain seated at 25% with the gearing you have.