It’ll be a bit faster, everything else being equal.

It won’t be slower down hill, as long as you’re used to it.

Pedalling up a steep fire road, as others have said, about 2%. Some benefit on the flat with less rolling resistance due the the lower overall mass, but the wind resistance will be the same. Some benefit on the downs from being able to accelerate faster and chuck the bike about easier (but on a terminal velocity descent you’ll be a bit slower as your drag will be the same but forwards force from your weight lower – this will be more than made up for by the climbs).

FWIW I considered the benefit of a dropper post, and decided it’s worthwhile on an XC bike to descend faster, despite the ~300g weight penalty.

Essentially it’s not going to take you from a mid field finisher to a podium regular, but it could make the difference between 1st and 2nd, or 21st and 22nd, depending on where you usually finish.

Plus it’s nice to know you’ve done everything you can to go faster and it’s just down to putting maximum effort climbing/maximum commitment descending on the day.

Edit- I run a Parkwood, but it’s more of an all-rounder, as I don’t do enough races to justify an XC race bike. TBH I could save 3lb by swapping the frame and forks, but it would cost me lots of money to the point that I might as well just but another bike…

Dropper, TBH i rarely use my dropper even at the best of times. I have a Magura Vyron i can swap in seconds from bike to bike (assuming a 30.9 fits of course) but even at places like Afan i rarely use it. Checkendon, i can’t see any reason i’d use a dropper though.

Depends on their power to weight ratios of course.

Exactly. The point is 2kg of extra weight on a bike will have more of a negative effect on a riders overall W/KG who is 60kg than a rider who is 90kg. 2kg of extra weight to a heavier rider will be less noticeable (less % gain) than 2kg of extra weight on a lighter rider.

Another example. My cars 0-60 is the same as a friends car. Mine has a much smaller engine and lower power output but still the same 0-60. Add 3 passengers to both cars and mine cant keep up anymore.

Intervals, yes, i’ll give you that… But i’m not a trainer road kind of guy.

The point of intervals is that they make you faster than just randomly blatting around at full gas in a race scenario, by doing super threshold intervals ou actually spend more time super-threshold as you allow your boody to recover inbetween, just going full gass you will be compromised and not hitting those max watts as regularly.

FWIW one of my favourite xc training things to do is to find a climb that goes straight into a singletrack descent, do hill reps but rather than stopping at the top, do the rep then straight into trying to ride the singletrack as fast as possible for a few hundred yards before recovering. Much harder to ride singletrack with sweat blurred vision!

Dropper, TBH i rarely use my dropper even at the best of times. I have a Magura Vyron i can swap in seconds from bike to bike (assuming a 30.9 fits of course) but even at places like Afan i rarely use it. Checkendon, i can’t see any reason i’d use a dropper though

Everyones different, and I’ve never even tried a dropper, don’t even have a qr seatpost – but I believe there are many a/b splits that I’ce gone B on where if I had a dropper I’d have gone A, so that means I’m either putting in another little sprint to get back to people (adding to fatigue) or being dropped if riding tight to someone in front. I reckon i might jsut have a paly with a seat lowered 10cm and see if I’m faster/more confident on the descents – woudl be good stanidng pedling training too!!

Dropper, TBH i rarely use my dropper even at the best of times. I have a Magura Vyron i can swap in seconds from bike to bike (assuming a 30.9 fits of course) but even at places like Afan i rarely use it. Checkendon, i can’t see any reason i’d use a dropper though.

Yeah it depends where and how you ride.

When I did the sums, I needed to save such a small amount of time on the descents that it was worth it for me – but I do like the saddle down even when I don’t *need* the saddle down, just to be able to chuck the bike around.

Also, I broke my wrist in an accident I probably would have avoided with a dropper.

Way I see it, if I’m going to be putting the effort in to train to be as fit as possible I may as well have the right tool for the job to get the most out of all that grafting on race day.

Not all weight is equal however.. Light wheels and tyres make far more of a difference than a light frame

Simple answer is yes.  How much is irrelevant.

The difference felt or seen on a 500g lighter bike may be negligible but differences nonetheless.

If you were comparing a 10kg bike against a 100kg bike I think the answer would be a bit moire obvious, but 10kg and 11kg is still a difference.

Simple answer is yes.  How much is irrelevant.

The difference felt or seen on a 500g lighter bike may be negligible but differences nonetheless.

If you were comparing a 10kg bike against a 100kg bike I think the answer would be a bit moire obvious, but 10kg and 11kg is still a difference.

If it’s a bike you know, the differece can be huge. Going from winter tyres to faster lighter summer tyres (probably about 500g difference, which you feel when just jumping on the bike, as well as the faster rolling which is a different matter altogether!) makes a big difference to the feel of my bike…

Edit – meant the difference can feel huge. 500g is not going to actually make a huge difference to your actual speed.

I also do a bit of XC racing on a heavy-ish trail bike.

Yeah I’d be quicker on a XC race bike but I’m not serious enough for one and at least it gives me a ready-made excuse for only being 4th in that “enthusiast” race mentioned above.

😉

Yeah I’d be quicker on a XC race bike but I’m not serious enough for one and at least it gives me a ready-made excuse for only being 4th in that “enthusiast” race mentioned above.

I take it we’re talking more fun here, as top 10 in Elite is bloody impressive

top 10 in Elite is bloody impressive

Althogh depending on what series 8th elite might well be second last [big smily laughing emoji to make it unequivocal I’m teasing the poster]

Bloody impressive getting to the level you get to race in elite though!

On a circular ride, you’ll get the potential energy back, so it’s really just kinetic energy. For me 2 kg extra means about 2.5%, so that’s the difference in mass, For the SAME power, that means a difference in velocity of sqrt(1.025) – 1 or about 1.25%, you will struggle to notice this compared with extraneous factors such as temperature, air density, wind, tiredness, etc… So the real world answer is none.

I can actually do this experiment on the road, as I have a Giant Defy Advanced SL and a Giant Defy 5 all alloy (including forks). The difference in weight is about 2 kg, but I already know that the alloy Defy handles pretty much the same as the much more expensive Defy, I haven’t done any timed routes to test yet.

So basically we’re left with

“Buy a bike if you want one…. but it won’t make you any quicker you fat ^$^%^& ”

🙂

Have a look at the Vitus Rapide Weeksy and tell me what size you are.   I’m thinking of selling mine and using the Scott Spark.

That mainly depends on this weekends race.  Its very non technical so the Spark is overkill but I need familiarity for my target marathon races.  Can I race on one bike thats 2lbs heavier?  Probably.

On a circular ride, you’ll get the potential energy back

Only if you don’t brake. And even if you didn’t brake, going up you are losing more than you can gain going down as wind resistance increases the power requirement for a given speed as a cube of the speed.

And even if this wasn’t the case, you spend more time going up, so you wouldn’t make the time back even if your downhill speed increased by the same proportion that your uphill speed decreased.

I take it we’re talking more fun here, as top 10 in Elite is bloody impressive

The Midweek Madness series in NW England only has two adult male cats, “racer” and “enthusiast”. The former is all lycra, the latter is a mix of lycra & baggies.

So basically we’re left with

“Buy a bike if you want one…. but it won’t make you any quicker you fat ^$^%^& ”

A proper XC race bike would be quicker for sure. People just enjoy being contrary on the internet.

People must race different XC events to me, I find the opportunities to pass on downhills / singletrack very very limited and for the most part too risky to try.  I used to use descents mostly to close gaps (if I had space) or recover and then absolutely smash any fireroad sections or dual track.  Best I did was I think 6th in BBD one year and a 10th overall in one of the Gorrick BM series.

I went from an old anthem x1 to a pimped scale with power meter / carbon rims etc… it didn’t make much of a difference.  The biggest difference to my performance was buying a road bike.

If you can handle a super light flighty bike they are really quick, round trail centres I am only slightly slower descending on the scale than I am on a nomad, but something like twice as fast ascending.

People must race different XC events to me

+1

Most of the elite events i’ve done over the years, the guys at the pointy end are seriously quick downhill.

Unless there isn’t any point in going fast, as you’ll only gain 3 seconds, but tire yourself out for the next climb/flat (and lose 20).

There is a difference between a downhill racers speed and an xc racers dh speed. If you are used to dh racing with good size rock gardens and decent size jumps then ill argue that xc downhills are pretty easy. I have passed many people by taking the risky line but in a dh race it wouldn’t even be considered an obstacle.  I found that even whilst passing people going down hill i was still able to get enough rest to recover for the next hill/effort.

Weeksy, for Checkendon- NO. IMO. What you will gain in the slight acceleration advantage you’ll lose in handling. It’s so rooty that you don’t need a light bike- you need a planted one. And it’s pan flat!!

What will gain you time is training. Skills sessioning  and intervals. It’s that simple.

Make up a course around your cul-de-sac going up and down the curbs and round parked cars and time yourself. Then try and get faster. It doesn’t need to be Swinley or BPW.

Your power curve is also too flat. It’s almost the exact opposite of the power demands of Checkendon. Work on it! Ten or thirty second sprints with big recoveries. Beast yourself up the Watopia hilly KOM (2min), recover and do it again.

Or use the workout mode and smash your way through one of the HIIT sessions.

Sitting at Threshold in a Zwift race won’t build you a top-end.

Relating it to my season last year- at my one XC and one CX  race, I lost out in the corners as simple as that. I had to slow much more than the others and accelerate much harder and whilst I could maintain that for a lap or two- my lack of efficiency ground me down much sooner. People spend time doing skills sessioning and clinics because it’s a huge part of off road racing .

Many of the guys you’ll be racing against will be racing all the time too.

I think a Southern XC podium is a huge goal (ie one that will take a couple of seasons)- looking at the results, the top of the Open category always feels a bit ‘sandbaggy’ 😱🤣

I think a Southern XC podium is a huge goal

I’m hoping that was for you ? As I honestly think it’s completely unrealistic for me 😀

In 2017 i was 9mins+ behind the winner and 7mins behind 10th….  It equated to 2 mins 15 per lap… I just don’t see how that’s going to be a realistic goal for me personally.

If i’m honest I finished 2mins 20 behind Yak of this here forum. He’s my target 🙂 Whether i can get closer this year, i don’t know…. but i’ll have a damn good try 🙂

I plan on setting/planning 2019 much better from a dates perspective and making it to far more Southern XC events. This season, i can’t do round 2…. but i’m thinking 1/3/4 i should be able to wangle with the wife/footy stuff and get to them.

Have you done Southern XC before ??

The only reason I ask is I reckon from the Zwift stuff we’re pretty similar, same weight power out stuff.

There was a younger faster version of me that I’m trying to get back to, the younger faster version of me could do a full lap of Swinley in 1hr:10m (i can’t get near that at moment) however in the Open Cat at Southern XC the best he ever managed was 18th

Some serious riders seem to enter the Open (they should be in Sport at least)

Bike won’t matter too much.

I built an XC race bike, not because I needed a lighter bike but because I wanted one set up for the purpose.  Short travel, skinny tyres, racy position and steep angles.  My Patriot isn’t an awful lot heavier, maybe 3-4lbs (the XC bike is heavy), but the riding position makes me want to just sit and spin in a relaxed way, whereas the XC bike makes me want to put the hammers down.  Might be psychological, might not.

Bike won’t matter too much.

Did the odd round on my bikepacking bike, fully rigid with bags still attached.

It’s childish but because I know I can’t win sometimes being the guy with baggies and the wrong bike is more fun. (especially if you overtake the odd lycra clad S-Works Epic)

The Midweek Madness series in NW England only has two adult male cats, “racer” and “enthusiast”. The former is all lycra, the latter is a mix of lycra & baggies.

This is true, and I’ve done a few 🙂

Basically, back to the bike thing, if you want a bike go buy it and stop trying to justify it with minute gains

Tiger.

http://my5.raceresult.com/66810/results?lang=en#3_77C4BF

33rd. ive done more Gorricks than Souterns though

20-25th is my aim

You see you look at that in context the Top10 in the Open Cat beat the hour for the course, all 10 of those would have been competitive in the Sport Cat.

I built an XC race bike, not because I needed a lighter bike but because I wanted one set up for the purpose.  Short travel, skinny tyres, racy position and steep angles.  My Patriot isn’t an awful lot heavier, maybe 3-4lbs (the XC bike is heavy), but the riding position makes me want to just sit and spin in a relaxed way, whereas the XC bike makes me want to put the hammers down.  Might be psychological, might not.

This is all true, but I’ve been trying not to talk about “other things” (including the rider) as the OP asked whether losing weight would allow him to go faster.

It would.

A bit.

How much depends on a lot of factors.

And re. people getting stuck behind folk on the singletrack, well that could happen wherever you are in the field, but it can happen uphill too. It’s definitely personal preference for droppers.

I don’t know why but I’ve always favoured heavier bikes. Bfe, Trans AM and currently looking at a Big Wig. Not a great rider and always find the weight reassuring when I fling myself down or over stuff. I’ve had lighter bikes and they just feel fragile even though I know they aren’t.

As a few people have alluded to – phsychologically it could speed you up.

If you aren’t collapsing at the finish line like Sam Gaze did this past weekend, then your body has more to give. There are many ways to get some of this out of yourself, but making equipment choices that you believe are faster can make you faster, whether that be the scales reading, the presence or absence of a dropper, or (so I hear) the feeling of air over fresh shaved legs.

And if you aren’t good enough to be at your true limit (I include most people in that), that psychological benefit could outweigh the physical penalty

Well I did write you a long answer to this question but this stupid site crashed and lost my text so you’ll have to settle with. No, it’ll make no difference.

That’s a shame. Still thinking about a light fast 29er FS, but the problem comes that a decent one and light enough would set me back about £4000. I don’t really feel the £4000 would be justified considering my lack of ability along with already having a damn decent bike too.

I really could do with weighing my t-130 though to see what it comes in at in XC trim.

It’s extra complicated because so much of it is software. I love the feeling of a light bike, and it makes me put more in- if the first pedalstroke feels productive then my next one is stronger, if every lift feels easier then I flow the terrain better. It’s not because the light bike makes it possible- I could do the same on a heavier bike, but I probably won’t.

Taking out 3 brake rotor bolts each end and stripping off paint didn’t make Steve Peat’s world champs bike faster… But possibly knowing his bike was as light and as ready as it could possibly be, helped him be faster. Special tyres Cole!

The total mass of rider; bike; cycling kit; emergency repair kit; water etc. will have a big influence on climbs of ~7% or greater. The steeper and longer the climbs are, the greater the benefit of the whole package being lighter.

You could test this yourself on Zwift, on the new Alpe Du Zwift, playing with the weight figure.

I noticed yesterday on that Zwift hill that even at 222W average for my climb from the second hairpin and then a full descent, the Calorie expenditure was huge, ~1100 Calories for 74mins25secs. I’ve put on ~2Kg since Xmas, now ~78Kg, this climb will be a good way for me to lose those excess snacks while trying to at least maintain (ideally improve) my sustained power output.

Why not get set off light wheels and tyres for racing. Rotational weight more important overall acceration etc etc if u can knock 500grams or more it will be noticable.

I have light rubber one Hope pro4s. Admittedly they’re the 3SW rims, so a long way from light, but I can’t go back in time and change that decision now, so the wheels I have are staying.

You could test this yourself on Zwift, on the new Alpe Du Zwift, playing with the weight figure

The issue with that is that a large majority of the course is fairly flat. So it’s not going to tell us much for the race.

Well that was interesting (to me anyway) I bought a cheap Chinese luggage scale thing from Ebay. Not for the actual weights of my bikes, but for the comparative weights compared to eachother.

The conclusion is, my Parkwood is 1.45kg less than my Whyte T-130 in full XC tyres (both bikes have Maxxis Crossmark II’s as their XC rubber, both tubeless)

I can only assume the forks i thought were very light on the Parkwood actually ARE very light…and the shock/frame on the T-130 are quite heavy. I know the wheels on the T-130 are not like being the super wide Hope 3SW’s, but i doubt the standard Parkwood Rattlesnakes are particularly light either.

But 1.5kg is a decent chunk of weight off the bike…. Hmmm food for thought.

Whipped out the wheels and did some more weighing

The rear wheel on the Whyte is 300gr heavier than the Parkwood, but the front is 200Gr lighter. Same seat on both. Cassette on the Parkwood is 35gr lighter. Pedals are 3gr difference in favour of the Whyte (Nukeproof).
Seatpost on the Whyte will be heavier as it’s a bit longer and fairly cheap too.

Both running exactly same cranksets and BBs. so it seems the majority of the weight is in the forks/frame rather than anything else. X Fusion Sweep RL2 are on the Whyte which seem to be around 1900gr and the Fox  forks from Germany everyone bought i believe are 1550gr… So there’s 400gr of it…