Weight of bike vs weight of rider for climbing ?
In your scenario I don’t think it matters where the mass is, some quick calcs taking into account drag, rolling resistance and gravity everything else being equal;
1 mile climb, 180m vertical gain;
67kg rider, 10kg bike, no camelbak = 593 secondsPosted 4 years ago
67kg rider, 13kg bike, no camelbak = 615 seconds
67kg rider, 10kg bike, 5kg camelbak = 630 secondsrocketmanMember
How would his times compare in theory ?
Purely empirical of course but off road my Voltage FR is as fast and in some places faster than my Cannondale Rize going uphill. The Voltage is a freeride bike approx 35-36lbs with 200mm of travel and the Rize is yer typical 140mm FS trail bike prob 26-27lbs. Wildy different geometry but very similar gearing.
A: The Voltage has more traction. It doesn’t get deflected by obstacles or spin up on loose surfaces. The difference is small but significant and it means my more of my effort is translated into going forward. The other big difference is that the Voltage is simply heavy. I used to think that this automatically meant draggy but the tyres roll easily, the drivetrain can be turned easily with one finger and the wheels spin effortlessly. Once the initial inertia is overcome it flies along.
None of this applies on smooth trails or tarmac of course where the lighter bike simply rolls away.Posted 4 years agocookeaaSubscriber
What is Rider A’s mass?
Surely it’s all about what proportion of the combined rider + bike + kit you are actually reducing.
Let’s say Rider A is 80kg so in the first case you have:
Case 1: 80 + 10 + 5 = 95kg
add 3kg to the bike and you have:
Case 2: 80 + 13 + 5 = 97kg
97kg all up mnass that’s a 2.1% increase in mass, so is it reasonable to expect either a 2.1% increase in his climbing time (for a 5 minute climb that’s an extra 6.3 seconds) or 2.1% more work required to maintain the same climbig time… seems fair, non?
Put Rider A back on the 10kg bike and remove that 5kg camelbak
Case 3: 80 + 10 = 90kg
that’s 5% less mass than Case 1 and 6.5% less than case 2…
realistically you are probably going to be dealing in a world of 2 – 5% of all up mass savings when your comparing a 22lb bike to a 28.5 lb bike depending on your BMI and propensity towards packing the kitchen sink… In terms of financial cost there’s probably a several hundred quid involved in a takeing 6-7lbs off the bike Vs relative pennies for leaving the camlbak in the shed…
So clearly the bigger impact on mass comes from leaving (an overloaded?) camelbak at home, but then you need to probably factor another ~1kg back in as it’s reasonable to expect you’ll be taking a bottle, spare tube, pump and multi tool as a bare minimum…
TBH I try to travel as light as I can at the minute while still having the kit to get me out of any reasonably forseeable situations… I’m less fussed over saving bike mass, I’d prefer it to be heavier but durable, carry a minimum sensible amount of kit, and then focus on reducing the mass of the meat sack sat on top…
Biggest variable is always the rider as a pricey 10kg bike could equally support a 60kg racing whippet or a 115kg biffer, and no doubt their lap times would vary significantly…Posted 4 years ago
The weight of the bike doesn’t make much difference when riding up a smooth gradient.
The weight of the bike makes a big difference to handling though, and also when going fast on technical tight singletrack. When you’re constantly accelerating, braking and changing direction the extra power you need for a heavy bike adds up to a fairly significant amount.
I used to have a 37lb coil sprung Patriot, when my other bike was a 27lb Fisher Cake. The extra weight was less than 5% of the total, but long climbs on the Patriot were bloody murder and made me lag far behind my mates on their usual bikes.
You can calculate all day but it’s fairly obvious that light bikes FEEL much quicker even if the number of seconds isn’t important. Of course, it’s only ever important in XC races anyway.
I think a large part of it is that if your riding mates start to pull away you’ll have to try that bit harder to keep up, and even a small amount of weight makes a big differenc when you are on your own threshold, because when you are at that threshold even a small increase in power (less than the 5% required to overcome a heavy bike) pushes you into the red zone where you’ll become knackered very quickly.Posted 4 years ago
Assuming Rider A is on a 10kg MTB and making a 10 mins climb with Gearing ratio Z
Assuming Rider A is on a 13kg MTB of simillar geometry, componentry etc but with a weight of bike of 13kg and same gearing ratio of Z…. How would his times compare in theory ?
Then… Assuming Rider A carries 5kg in his camelbak on the same ride on the 10kg bike… then does the same ride without camelbak, how would he compare ?
I guess the important point i’m getting to here is, “what makes the main difference, weight of bike or weight of rider?”Posted 4 years agocookeaaSubscriber
Well rider/bike/kit mass isn’t the only variable to consider, a bikes geometry and suspension action might not suit the type of riding: Mechanical advantage for pedaling up climbs can be traded of against handling or vice-versa, you might well have draggier tires (at lower pressures?) that adds a couple of percent more to the required energy input to move it, the combined factors can soon all stack up…
molgrips GF Cake – Vs – Patriot case probably had all of the above as a factor as well… ?
We live in the age of the ~30lb DH bike, I’d still not like to try and pedal a 61 deg HA / 2.5″ (sub 25 psi) tired / 8″ travel / 1 x N (road bike cassette) bike back up the hill however light it is…Posted 4 years agojamesoSubscriber
Save 5lbs on the bike and you ‘notice’ it there and then.
Save 5lbs on yourself via some training / more riding over a month and it’s less instant and not as noticed, but you will be going faster than your ‘5lbs lighter from posh bits on my bike’ scenario.
Unfit riders on light bikes are cheating themselves of the advantages of weight training.. A fit + lean rider spending most of their time on a heavier bike will do best come race-day on race-bike.Posted 4 years agopopmatikMember
Good topic this. I wonder about this stuff as my bike is heavier than my riding buddies.
I have an orange five (pretty standard kit on it) and he has an Ibis mojo HD.
I weight just under 10 stone and i’d say he weighs around 12. He always beats me up hills, but that’s because he is fitter. If I got up to his fitness levels in theory would I be quicker? 🙂 Not that any of this matters… I just want to take the piss out of him buying a deeply expensive light carbon bike.Posted 4 years ago
Weight loss of the rider can be achieved at cost=0 so do that first,
£0 yes, but it’s often rather hard. And if I am already trying to lose weight, then I could still spend money on my bike too, coudn’t I?
It’s not either/or.
you might well have draggier tires (at lower pressures?)
You are quite right, the Patriot had a number of issues hindering the climbing. The bike that replaced it after it got nicked was an XC spec Patriot, air sprung etc etc which weighs about 31lbs, including Kenda Nevegal blue groove tyres. When I got it it was still a bit of a chore, but removing the buffalo hide tubes and going tubeless for lower rolling resistance made a massive difference. I can now ride it happily all day, and only the somewhat more upright position is a slight hindrance over the 5. I equalled my PB at Cwmcarn on it – I was 2 mins slower on the climb than I was on my 5 but 2 mins quicker on the descent.
Having said that, my Kona Heihei is far quicker than both of them up the climbs obvioulsy but also on the singletrack. It rolls much better with its Racing Ralph tubeless tyres, but also accelerates far better out of corners with a stiffer frame and lighter wheels.Posted 4 years agoshortcutSubscriber
It is shocking that noone has asked for confirmation on wheel size. Given that this is a constant I would suggest that the first rider to the top is the one of the light bike without the bag.
Next up is the one who is 3kg fatter but still on the light bike.
Next up would be the light bloke on the heavy bike followed by the heavy guy on the heavy bike.
My assumption is that the trail is the same. Power is the same and wheel size is constant (clearly anyone with bigger wheels will be quicker).
My reasoning is that dynamic weight (on the rider) is better than weight on the bike. So having a poo before a ride is not as good as having a lighter bike.Posted 4 years agocrikeyMember
Play to your hearts content, then ride your bike a bit more and step away from the cake, fatty.Posted 4 years agofeistyMember
I have a 29er Scandal at 23.4 lbs and a Niner A9C at 16.2 lbs and I weigh 148 lbs
Being light the 7.2 lbs difference is 5% of my body weight and would be hard for me to lose on my body so very worth while.
The biggest benefit is the weight loss on the wheels which was the best part of 2 lbs and makes the bike accelerate like a rocket and is real world noticeably faster up the hills. My ride times on regular loops from 15 to 50 miles are consistently faster by around 3-5% if not more on the hillier rides.
So you question is subjective more about where the weight is saved, if it is saved on the bars, seat, frame etc that small amount of weight loss will be barely perceived but if saved on the wheels would provide a very real speed gainPosted 4 years agocrikeyMember
makes the bike accelerate like a rocket and is real world noticeably faster up the hills.
Oh please, do give over…
Every time there is a weight thread on here people come out with the most amazing superlatives, the massive difference, the wonderful acceleration, the fantastic performance upgrade, and no one, not a single bloody one, ever backs it up with some real world numbers.Posted 4 years ago
Because however great the difference feels, there is never that much difference when you actually try to measure it.DanWMember
Unfit riders on light bikes are cheating themselves of the advantages of weight training.. A fit + lean rider spending most of their time on a heavier bike will do best come race-day on race-bike.
“Weight training” by riding a heavier bike is classic. I mean, you couldn’t ride a harder gear on the same light race bike in training to increase the intensity could you? 😉Posted 4 years agofeistyMember
I bet I have more real world experience than you to judge having two bikes with similar Geo with thousands of miles on over the same loops all gps logged and my statements is based on actual ride times not solely how it feels”
I am not a tard who believes in every stupid old wives tale, I have a carbon frame and an aluminium frame and you can’t feel any difference from the material, all this steel is real, Ti this that and the other is all rubbish, but rotational weight is a fact, you may want to re-read my post as I even said weight lost elsewhere is pretty pointless and that is coming from someone who has spent 6k on a bike to make it crazy light because I like the challenge and building light bikes.
And as for cheating myself I am sure I would waste most people on my weight weenie 32:18 singlespeed as I have trained hard and am very fit so storm up the hills
The bitterness towards people on lightweight bikes always amazes me, normally is seems to be bitterness from people who can’t afford to spend on a bike.
I ride unicycles as well and have some a stunning 36″ ti Triton (like the looks not the frame material) and Loved how friendly and non agro the community is no-one cares what wheel size yo run (we have far more choice) whether you ride MUni, Trials, Street etc, maybe you have to be a bit loony and not have any ego (you do look a bit stupid lol) so you don’t get all this raaar your stupid for doing blah or OMG why do you ride wheel size blah
I like things with wheels, I like being out in the wild, I like tech and the excitement of buying stuff and talking about it.
Time to step away from the internetPosted 4 years ago
no one, not a single bloody one, ever backs it up with some real world numbers.
It’s cos we don’t have that data. We may waffle on about this stuff when we are sat t our office desks being bored, but most of us are still a long way from being sad enough to spoil a good ride by faffing around collecting stats!Posted 4 years ago
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