Lighten my bike or new XC build

I’m currently racing XC on a Tarn Ti with pikes. It’s not super heavy (12.6kg with flat pedals, pump, EDC, cage and front mudguard) but also not xc bike weight. Geometry is not dissimilar to a modern xc frame but I can’t help wondering if a race targeted bike would be faster. I don’t think there is scope to knock that much off the current bike. Swapping to SID 35s probably worth 200-300g and there are lighter wheels than the 350/xm421 combo I have now (1750g). Other than that I’m struggling to see any significant savings short or not running a dropper. Rest of the major bits are oneup bars, RF turbine stem, Magura MT trail sport brakes, xtr shifter, slx mech, Turbine cranks, one up dropper, charge spoon saddle, lightweight SRAM 11spd cassette.

New bike wise I’m not keen on carbon so would be looking at something like a specialized chisel. This would mean new forks as they are max 110mm travel and my pikes are min 120mm. A different frame would also allow lighter cranks (current frame needs a wide axle which limits choice somewhat). That is already looking around 1-1.2 kg lighter (in my head), with potential for more with different wheels. Is it worth it for consistent midfield finishes, probably not but then I’ve also never had a light race bike before.

Any thoughts on how the current bike could go on a diet or alternative frames (possibly that could handle 120mm forks initially) that are worth looking at.

I think you’ve hit the nail on the head, you’ve got all the main components down to a decent weight at a decent budget, to go lighter you’d have to pretty much change everything to a much more expensive type/model, each item only saving grams, but collectively saving hundreds of grams if not kilos. So it’d be cheaper to buy again.

I looked at a high end xc bike in the sales, it had a great spec but not a great looking frame, so it would still be a cost benefit to buy this and use is as a donor bike to the frame of your choice. I did look at Chisels, but their specs are crap, and they’re expensive as a frame only, they were selling at half price for a full build, so could be economically to buy two bikes and swap the parts over. 😎

This was the donor bike I saw, looks like I left it too long.

https://www.paulscycles.co.uk/bikes/mountain-bikes/lapierre-prorace-cf-99-carbon-hardtail-mountain-bike-2023-black__12638

My wife recently got the Prorace 7.9, it’s really nice, the only downside being the quoted max tyre size of 2.35″ is really pushing it, unfortunately it also came with 2.35″s! Might get away with it in dry conditions but in mud I’d be quite scared.  Turns out it’s quite hard to buy narrower ‘year round’ tyres without going full mud tyres or non-tubeless.  Managed to find 2.25″ Nobby Nics which have acceptable clearance.

Paul’s have it left in XL for an absolute steal.

PS Pretty sure I weighed it at 9.95kg (size small)

I had a Cannondale scalpel for a while. 26″ wheels, Full xtr.and a lefty.

I’m unlikely to ever ride a MTB that is lighter. This is it’s wasn’t very durable. The linkage broke and was pricey to replace.

After that I lost the love of getting the wheels off the ground at all. Even a front wheel lift made me twitch.

I moved and sold it for a mixture of the space and not really wanting to ride it.

If you are smashing your self to your mid pack finish, is a slightly heavier more robust bike not going to be more confidence inspiring?

I’d rather finish 30th than dnf because some hyper light part snapped.

Bias alert
I tried one xc race when I thought it was fit. I was top quarter in the fun category. My time wound have been well off the back of last in sport.

I commited to a second race in the series and it took all the fun out of riding. Trying to beast myself for 6h a week for a month just to finish a bit faster than some blokes I’d never met wasn’t for me. I stopped wanting to ride at all, until I decided I wasn’t going to do the next race.

Tried an enduro 86/89 riders 😧
Got passed by someone in elite, there is no chance I could have got round any corners doing his speed.

Tried another xc race 5 year on. My mate lapped me. Turned out he had been toning it down when we rode together for years!

Good wheels would save over 400g.  Tyres might save another 150-200,  forks another 300-400g.

My Titus El Viajero is just over 10kg in winter trim and just under 10kg in summer trim – I could probably drop another 500g from that if I really tried.  My Transition Spur is only 11.1kg.  Both are large, both of these are weighed, not guessed and both are without pedals.

The builds are high end, but not exotic.

Ti rotor bolts FTW.

I did look at Chisels, but their specs are crap, and they’re expensive as a frame only, they were selling at half price for a full build,

Yep, I got a Chisel Comp at half price last year and for the money it was very good. At full RRP, it would have been quite poor value.

However, it’s the same frame across the range (2 build options and a frame-only) and I’ve seen various YouTube videos of people building them up as no-expense-spared XC builds, it will go very light if you throw enough money at it.

SIDs, carbon wheels and a 1x XX would easily take it down to sub-10kg.

I saw the prorace but discounted it as 27.2 and I’m on the border of the L/XL. Also from where I’m sat lappierre’s shelves are looking very bare. I’m wondering if they are in trouble. That is the sort of thing I’d probably use as a base though. A lot in the price bracket come SRAM gearing and brakes that would be straight up for sale.

The chisels spec is not great, from the look of it I’d be selling everything and just keeping the frame (better than the frame only price). Seems to be a few 22 spec ones around with a good discount in the right size. I think the frame hasn’t changed as the numbers all look the same. No sign of a 24 model though…

400g off the wheel seems a lot without £££££ and carbon. My preference of 240s with a 25mm alloy id rim comes in around 1500g. What spec are you thinking of that comes in that much lighter?

Tyres currently are barzos. Not the lightest tanwall version but the black version that is not much more.

Is it worth it for midpack is a good point. I do enjoy it and already do 6+ hours a week anyway. I’m fitter this year and back to within 1kg of lowest adult weight (though more muscle this time). There is not a lot of scope to lighten me instead.

https://www.merlincycles.com/dt-swiss-xrc-1200-25-spline-boost-carbon-wheelset-29-303215.html Surely this is the wheel option you’re all looking at? Especially if 25mm inner is fine. I think there is also a code for 10% off

My trouble with all this weight weenie-ing is you turn up to a race in the UK and your bike ends up so clogged up with mud you’ve instantly put on 5kg of extra weight so is it worth it? (Last race I did was the Welsh xc series, it was WET!)

I was looking at 240exp centrelock hubs on xr391 rims with competition race spokes and alloy nipples. Similar weight to that carbon set but not carbon. That is a huge discount though!

One good thing with the current Tarn is the mud clearance. Frame will take 3″ 27.5 tyres on the back with loads of clearance so subsequently clears mud really well. This is also the reason I’m limited on crank cover though.

Turns out it’s quite hard to buy narrower ‘year round’ tyres without going full mud tyres or non-tubeless.

I encountered this a while back and bought a OEM tubeless ready tyre that had been swapped off a new bike as not gnarly enough at an lbs.  What width are people riding XC on these days?

As to the OP I’m in the category of if a light bike suits most of your riding you’ll get better results from a new bike than a lot of faffing with upgrades.  I used to endlessly tinker with set up back in the day and rarely ended up with an improvement that justified the outlay. Learned a lot of spanner skills that have saved me a bunch in workshop costs but that’s not the same as having a better for the purpose bike.

If you’re likely to break an XC noodle then forget the results and ride something robust to a mid pack/tail end charlie finish.

I’m fitter this year and back to within 1kg of lowest adult weight (though more muscle this time). There is not a lot of scope to lighten me instead.

Got any tips for how to get in shape? I would love to be able to say that this time next year 😄

Ti rotor bolts FTW.

And you don’t need 6 per wheel either, remove 3 and you can save even more weight and some money.

Got any tips for how to get in shape?

Take up running, give up drinking and cut down on eating.

Turns out it’s quite hard to buy narrower ‘year round’ tyres without going full mud tyres or non-tubeless.

I’ve used several sets of older tyres tubelessly, i’m pretty sure that some of them even predate the existence of UST… So don’t get hung up on “non-tubeless” being an issue. They will go up tubelessly, and work well.

Your bike is over 2kg heavier than my bike when I last entered an XC event, I did the Gorricks for years and then later did the Glentress 7 every year, in a pair.

On One 456Ti built with a 150mm fork and a light, strong (but not cheap) build of 10kg in an XL/20″.

It wasn’t a twitchy head ar5e up bike which gave it a real advantage on anything remotely steep/iffy compared to those of equal ability to me on proper XC race bikes – very much like your Tarn but as it was a 26″ built up a lot lighter for equivalent strength and I reckon the frame was probably 1kg lighter (as it was made before the strength tests came in) so you’re thoughts of losing another kg feel right.

Remember the old adage; light, strong, cheap – you can only pick two.

 I can’t help wondering if a race targeted bike would be faster.

I think you’re probably kidding yourself if you genuinely believe that saving a few hundred grammes, even a kilo, from your bike either by upgrades or replacement is going to give a good return on ‘fasterness per £ spend’. You’d probably be better off investing in a good coach / thinking hard about race nutrition / buying some new, faster-rolling tyres / coke, hookers etc.

I would get some lighter wheels.

 This would mean new forks as they are max 110mm travel and my pikes are min 120mm.

I think you’d find that you wouldn’t even notice the difference in handling between 110 mm and 120 mm. Might be a problem for warranty, but obvious thing to do is fit some shorter forks if you have to take it back to the shop. (The warranty thing is a legal issue, not a safety issue. The stress on the frame won’t be any greater, it just gives the shop an excuse to refuse warranty.)

Wheels
Forks
Cranks
Cassette

But they all cost a lot of money.

If you’re racing, why not use spd pedals? I find flats significantly slower when sprinting or on climbs.

The last XC race I did was Cannock and that was on a rigid build without a dropper so you could pickup some cheap rigid forks and seatpost to try out.

What dropper are you running, a Fox transfer SL can shave off circa 250g potentially.

Got any tips for how to get in shape? I would love to be able to say that this time next year 😄

I’ve lost 7kg since Christmas and like the OP have got to within 1kg of my 28 year old self. And feel pretty good, and find climbing on the bike to be so much quicker.

But I’m not sure you want to repeat my way as it is too much for some/probably most, it does work though.

• Cut out the booze
• Do intermittent fasting (only eat lunch and dinner between the hours of 12 noon to 8pm)
• No snacking
• Strength training 2 times a week
• An hour of exercise – at least – per day, often in the morning fasted, this includes longer rides at the weekend.
• Sleep at least 8 hours a day
• Drink plenty of water

I’d be amazed if you can get wheels at least 400g lighter (so 1350g) for reasonable money even the very best carbon XC wheels such as the DT Swiss XCR1200 Spline 25 are quoted at 1411g , although I’d be going Spline 30 which are 1480 are over £2k retail or if you’re feeling really flush  the Silverton SL-30mm are 1280g, but £4k a pair!

Decent forks are also stupidly expensive for maybe 2-300g savings, but considerably better value than cassettes at the top end of the scale.

Essentially if you want to go lighter, flog the Tarn and get new bike as it’s better value in the end. But modern XC race bikes, especially FS ones aren’t as light as you’d think – certainly not 00’s level of silliness – as  they’re built to withstand WC XCO courses, some of which would make the majority of riders on here reconsider their life choices if they had to ride them on a proper XC race bike.

Tyres are an easy win, you’d be surprised what you can get away with on an XC race course once you figure out how to ride them, plenty of riders on the likes of Mezcals, Fast Traks, Rekon Races in all bar the shittiest of conditions. As is dropping the unnecessary stuff like pump, EDC tool, mud-guard etc. there’s 3-400g off your bike straight away.

Do intermittent fasting (only eat lunch and dinner between the hours of 12 noon to 8pm)

Isn’t that normal? Fasting isn’t eating at normal times, its not eating for more prolonged periods of time.

FWIW my XC race bike is a KTM Scarp Prime (pretty light 95mm travel XC frame) Fox 32 SC Performance Elite (could save a few g’s with a KaB0lt) full XTR M9100 gruppo, 160f & 180r rotors, MT Zoom bars, very light stem, ESi grips (easy win) Brand X dropper (could fit a slightly lighter one) Hunt Proven XC hoops and Spesh Fast Trak / Renegades in a large equivalent and it’s 11.3kg with one cage & pedals, nowt else. It’s reliable, faster than me and can handle anything I can chuck at it, but it wasn’t a cheap bike (£6k ish) when I got it in 2020, then chuck another grand at it in the form of wheels – how much do you want to move up a place or two?

I’ve done both – lightened a Trek Stache, which is no way an XC hardtail, and did well on it. Then upgraded to a Scott Spark and have also done well on it. The Spark is obviously faster. Both options were good – the Spark is lighter and more comfortable.

But modern XC race bikes, especially FS ones aren’t as light as you’d think – certainly not 00’s level of silliness – as they’re built to withstand WC XCO courses, some of which would make the majority of riders on here reconsider their life choices if they had to ride them on a proper XC race bike.

This.
I remember the early XC race courses of fireroads and sort of mid-level singletrack but races now are way more technical and demanding on bikes and kit.

My sub-20lb titanium hardtail was brilliant to ride on smoother courses but I can imagine going back to it now after riding modern bikes would be absolutely terrifying! 😂

Specialized Roval Controls are 1450g and about £1200. Any lighter and its almost double the price.

I wish Specialized would stop dicking around with the Chisel and make the frameset a sensible price and spec the full bikes with what people actually want – they would absolutely clean up the budget xc market.

I’ve also noticed a few weird deals on Lapierres – lad was looking for a suspension bike recently and this stood out a mile. Unfortunately not what you want but it insane spec for the money – carbon 150mm frame, carbon rims, mostly xt including 4 pot brakes and Fox kashima fork and shock for £2.3k.

https://www.paulscycles.co.uk/bikes/mountain-bikes/lapierre-zesty-am-cf-89-full-suspension-mountain-bike-2023-blackgold__12633

For some reason part of my last post never made it through. I added that worrying about weight is a waste of time if you’re not using SPDs.  Why worry about a pound or two when you’re not maximising your pedalling efficiency?

Race geometry is important too by the way. It’s one reason why my Spark is faster than the Stache, as well as being 3lb lighter. Your Tarn is probably not ideal in that sense, but slap a longer stem on it, with fewer spacers under it and possibly a narrower, lower bar and you’ll be in a much better position to put the power down. Increase the angle between your back and your legs and get low. I did this to the Stache and it really helped.

Combine that with some decent tyres (Specialized Fast Trak and Renegade or Maxxis Forecaster and Specialized Fast Trak for me) and some SPDs and you’ll notice a difference in how much power you can put down and how efficient you are without spending loads of money.

How about a set of these:

JRA Monitor Carbon Wheelset from £845.00

hubs choose from any of our J-bend or Straight-pull, centre-lock or 6-bolt disk mount including Son dynamo hubs
rims Monitor carbon rims
spokes Sapim CX-Ray black spokes
nipples Sapim secure-lock nipples – as selected
weights 1366g pair
* weighed with rim tape and Shimano freehub
freehub Shimano 11 speed or Campagnolo 12 speed are included in base price. All other freehubs are available at extra cost.
rider weight limit 85kg for most 24-spoke wheels, no weight limit for 28 spoke wheels.
recommended tyre widths 32-57mm

Err, there were still some gnarly xc courses in the old days, they just weren’t so man-made. Mrs did a world cup in Norway in ’96 that was over massive rock outcrops – with vee brakes and elastomer Pace forks she couldn’t lift her arms at the end 🙂

Got any tips for how to get in shape? I would love to be able to say that this time next year

Similar to @didnthurt. Though I have only slightly increased exercise level (more Z2). Large reduction in alcohol intake for other reasons had a near instant effect on weight, also improved sleep (better recovery). I still need to reduce cake consumption and add in a bit more running.

Cassette is in xg-1195 10-42. Going to struggle to trim weight there :D. Dropper is a V2 One up 180mm in 31.6mm, 545g according to their page. Swapping to V3 of the same would reduce to 470g (+ti bolt kit) or going to 150mm post would be 423g. The Fox SL is about 10g above that.

ESi grips (easy win)

Yeap got those :D. Tools etc will be off, I think for race time I’ll carry just a super light plug kit. Anything else is likely to be DNF anyway. Tyres are barzos already but will be getting at least a rear mezcal this year for when (if) it gets dry.

If you’re racing, why not use spd pedals?

I raced last year on flats but after doing CX on SPDs this winter planning to race SPDs this year. Need a lighter set though as the current SPDs I have are 500g+ (more than the flats :D).

For the wheels one option I have is to swap the hubs between my two bikes. The rims are the same ERD and the sus bike has lighter 240 EXPs. The lighter spokes from the tarn would offset the hub weight increase on the full sus and new Comp race straight pull spokes in the 240s. That would give a 1610g set of 1560g with xr391s. Fairly low cost option (£70ish for spokes + my time).

At the moment I’m flipping back towards seeing how I go this year with SPDs and my lighter weight, then maybe wheels changes (as any replacement bike would use those anyway). Yesterday I’d ordered (in my head) something different :D.

Race geometry is important too by the way.

This was one of the things driving thoughts that a frame intended for racing may be better. Bars are 780mm wide currently. I really want to move those onto my full sus though so swapping down to something more like 740mm is an option. Got several spacers that could be moved, stem is I think 50mm so scope to go out to 70mm there.

For exercising, as well as the Z2 I’ve been doing Yoga and Kettebell workouts.  As well as the cycling fitness flexibility and core strength is important for XC, especially as you get older.

Bars are 780mm wide currently. I really want to move those onto my full sus though so swapping down to something more like 740mm is an option. Got several spacers that could be moved, stem is I think 50mm so scope to go out to 70mm there.

I’d try that first. It might save you hundreds swapping stuff about only to find the bike isn’t much faster because you’re still too upright.

For reference while watching the Cape Epic, they’ve just done a bike check on Nino Schurter’s Scott Spark HMX Custom bike and in race trim for that event, with 2 cages and a pump its 11.29kg and that’s dripping with absolutely everything you could possibly throw at it from the top line of components, including custom / pro only edition 2.4″ Aspens.

That is scary light considering its full sus, loaded with accessories, has a PM, GPS and flight attendant.

It’s actually slightly heavier than my Spark (admittedly without anything bolted to it). I’d say it’s pretty beefy for a WC XC bike but it’s the way things are going.

Spending a lot of money to save 1KG is never going to be worth it on paper.  It may make you feel like you will be faster and may help motivate you to try harder but that won’t technically be because the bike is 1KG lighter.

The bike I ride on the road is 5.7KG and I am no faster than I was when I had a heavy steel bike that was close to 9KG.  I still love riding the 5.7KG bike though and would always take it over the 9KG bike, just because.

I’m going to try the position change as soon as I can get some suitable parts and then take it from there. The JRA wheelset is tempting though so is buying the rims and lacing them to my 240s.