Bought a Scott Scale RC frame about a year ago, built it up with bits I had and have been lightening up the build ever since. Its got all the silly bits on it now and goes around 16 Pounds on the scales.

Its a rigid by the way, I have really loved riding it and it feels super fast. Went out with a pal the other day for a ride and had a job keeping up with him. Im normally much faster than him.
He could have got faster but I think Im not as fast as I used to be on my normal 23 Pound-ish hardtail.

Have I gone too far?

Top troll.

Remove the seatpost.
Pour in some ball bearings.
Replace seatpost.
Ride with your mate again.

Repeat until you are faster than him.

picture……

Your bike has nt got slower, Your mate has nt got faster, you’ve got slower or maybe just old.

Depends on the terrain I’d reckon. If it’s all fireroad you might expect you’d be quicker (all other things being equal of course) but if it’s bumpier you might find it harder to hold a line.

That’s what a mate who got a much lighter bike reckoned anyway!

He wasn’t faster, it was visceral speed.

”Top Troll”

Please explain?

They only weigh 8.7kgs from the crate, why does that need to be lighter?

Oh yeah, you can also have an off day when you are not as quick as you could be.

It’s the forks, not the weight.

I reacon so. nothing wrong with a burly bike imo. i went out on a light hardtail tother day and felt like i was bouncing from rock to root to near disaster ! On a heavier bike i feel like Im part of the trail . Oh and climbing sucked on light bike too which suprised me . Couldnt get the power down what with all the bouncing around !!

Light bikes dont do cut’n’paste.

Light bikes dont do cut’n’paste.

you’ll need a mouse or some clever stroking of a touch screen for that.

Ive got quite a heavy bike, but Im generally first to the bottom of each hill. So that makes me the fastest rider in our group at least half the time – Im quite happy with that.

I had a similar question a while back, and I think the answer is yes: (so I am now getting a full susser)

http://singletrackworld.com/forum/topic/can-you-make-a-bike-too-light

fastest rider in our group at least half the time

Most people tend to spend more time climbing than descending so surely you’re only fastest for maybe 33% of the time 😉

Ah yes, thats probably correct wwaswas.

Unless we go to the Alps where the only climbing is lift assisted 🙂

DezB is probably correct, there is more to it than weight.
Everything else being equal a lighter bike will be faster, but I think yours is likely to be more skittish and probably a pain to hold a line with, especially with rigid forks.

wwaswas is right, you can spend 2 hrs climbing up a friggin alpine forest road for 20mins of descent (5 mins if you’re Danny Hart), so yer maths ain’t right. Also, you might be fastest on the descent, but your mates were waiting at the top for you for about 10mins. 😉

There is light, and then there is ‘not fit for purpose’.

A lighter bike will require better quality suspension than a heavier one – unsprung weight vs sprung weight.

And has he a big chain-ring and you haven’t, or was it just you’re afraid of punctures and have your tyres pumped up high?

Maybe try adding weight with bigger tyres run at lower pressures, for more grip/’suspension’?

Did you forget to have a poo so the extra weight slowed you down?

Or it could be that your mate did have a poo when he normally doesnt have a poo, so the extra weight saving made him quicker than you?

Theres more to it than bike weight alone…

There is light, and then there is ‘not fit for purpose’.

Similarly, there is good light-weight and bad light-weight.

You can lose a ton of weight by running CX tyres (on your 29er anyway) but honestly, would you?

Light-weight carbon rigid fork will only make you faster on fireroads, but a SID XX is going to be both lighter and better performing than a Tora.

So to back up what br said, it’s only too light when it’s not longer fit for purpose.

LOL@funkydunk
Also, urinating in yer mates shoes will lose you approx 500gms, then you’ll be riding like the wind, with him in hot pursuit to rip yer head off.

It’s the forks, not the weight.

+1

You’ve built it to be light over functional. It will excel in some areas because of this, and it will fail in others because of this. If your mate was quicker on the climbs he’s also fitter than you.

Given the bike is small percentage of rider+bike weight unless you are a 50 kg featherweight then shaving 1kg or so of he bike to get it to 16lb is not going to make that much difference to the rate at which you can climb. The fittness, stamina and skill of he rider is far more important in determining overall pace.

That is why I don’t bother trying to make m bikes lighter, if I want to be faster I should get fitter first.

Has anyone ever actually confirmed that whole ‘weight on bike/weight on person the same’ thing?

I know my bike feels far better than a bike 2kg lighter. But I can’t really tell if I put on a couple of kilos.

If you ride smooth you will be faster, if you know how to carry corner speed you will be faster, if you choose the right line and don’t brake you’ll be faster.

I don’t think it has much to do with bike weight, but a lot to do with these other factors. This is why you get quicker if you ride the same section over and over.

(I’m repeating here, but…) it’s not the lack of weight, it’s the lack of function. I have a <22lb full-sus, and I never wish for something heavier on my normal riding, but then that has a full complement of normal functional bike components (OK so maybe the fork isn’t quite as capable as something heavier, but it’s still a sus-fork and more capable than me).

Most people tend to spend more time climbing than descending so surely you’re only fastest for maybe 33% of the time

And you are the slowest when you are waiting at the bottom. Anyway if you ride with other people then assuming you all start at the same place, finish at the same place and wait at the end for the last rider before going home then your average speed is exactly the same as everyone else’s.

Thanks for the replies.
I think Purser_mark could have his the nail on the head.

The Weight weenie bit has taken over.

aracer.
Good point too.
”it’s not the lack of weight, it’s the lack of function”.

Maybee I should forsake a pound or so and get a good suspension fork.

So…DT Swiss or SID?

If I were to build a 16lb MTB over my 26lb Orange I would end up loosing 4.54 kg I would have lost ~4.5% of my total bike + me mass.
I am 94 KG kitted up.

That means my acceleraion is ~3.6% faster on flat smooth ground. Up hill on bumpy ground it is going to make some difference but not alot. The main difference will be on long climbs as you will tire a little less qucikly but not by much.

Lets say you do a climb at 7 mph and you have 100m height gain over 1000 m (I will assume the same tyres, pressures e.t.c) and you are me with at 95 Kg kitted up. Given the weight of the bike + me on either bike is nearly the same the rolling resistance will be nearly identical and I ignoring air resistance at these speeds. I am also ignoring the rotational K.E energy of the wheels as I want to do these sums today.

Light bike energy used in climb
= (101 x 9.81 x 100) +(0.5 x 101 x 3.1^2) ~ 99600 J
Ornage bike energy used
= (106 x9.81 x100) + (0.5 x 101 x 3.1^2) ~ 105000 J

Given the slope is 1000 m long and the speed is 7 mph or 3.1 m/s the time taken is 323 secs. Therefore the power output of me on the light bike is 308W 😯
On the heavier bike my power ouput is 325W. The difference is real and both figures would be higher if rolling resistance, air resistance and rotational K.E of the wheels is added in but the differences are not big either. Also I do not think I could sustain 308W.

Now doing more sums in my simplified model, if I was able to sustain 325W (I can’t) on the lighter bike I would save about 16 second at this power output on this fictious climb over being on the Orange. Which at my level of competitiveness is going to make sod all difference when I race but could affect placings for those after points.

P.S these numbers are fictious as I have ignored rolling resistance, air resistance and rotational K.E of the wheels. I have also assumed a flat hard climb at constant gradient and a rider who maintains a constant speed. When all these factors are taken into account I am sure the difference in time will be a fair bit less.

When I have tried light bikes I have felt a noticebale difference in the way it rides/ acclerates/ handles but I don’t think I was any faster in the real world.

bm0p700f
Wow..! That is an indepth answer.
Kinda makes me think a light bike is nothing more than a money pit.

Interesting though.

Also I do not think I could sustain 308W.

For 5 minutes, you may be able to. My 5 minute max power is c360W and I’m 2/3 your weight!

For 5 minutes, you may be able to. My 5 minute max power is c360W and I’m 2/3 your weight!

Apparenlty my 5 minute max power is world class, if I was a girl and weighed half as much 🙁

I still like my bikes lighter though.

Yep,
I like my bikes light, always looking for lighter kit. Im a average middle of the pack type climber. I think a light bike makes me a better climber.
Agree down the other side is a bit of a bumpy experience and fitness ist what it is in the summer but, just cant get used to the fact a previous back of the pack guy is now pulling me along.
A bit of everything is my asumption.
He has got a bit fitter.
I have got a bit un-fitter
Bike is too light on everything but the climbs.

Now all I have to do is sort it.