Im looking at building a single speed rigid bike for XC.
Below is spec ive come up with so far. The weights stated is what is the manufacturers claimed weights (clearly these will be out a bit)

Questions: What would you change? How can I get it lighter? Current budget is £1000 (already have cranks, brakes, chain and some other bits).

Not running your Crests tubeless?

A few squirts of sealant will weigh less than the 300g you have down for tubes. You don’t need a rubber rim strip with Crests, just the yellow tape (which weighs naff all) 80ml of juice per wheel.

Edit:- you can also shave a few grams from your 1kg tyre estimate. Even a sensible tyre like a Racing Ralph (i.e not too narrow or paper thing) will weight less than 500g an end at 2.1″

Flat pedals see a bit odd on a lightweight XC bike. A set of Eggbeaters will save a bit of weight over the flat pedals.

I would be. Thought I posted up the final spec idea! Anyone think this is a bit too ambitious?
Also after tyre suggestions.

why does it need to be sub 17lbs? just askin’

Swap the saddle for a Selle Italia C64, that’ss drop 100g straight away. I have one on my road bike and if you’re happy with the slr you’ll like the c64. It does cost a substantial amount of money though.

SLR is lighter than that IIRC, is that the weight for the XP? Bars seem heavy are they risers? Could look at MtZooms. Is the Hope headset 140g? That could be lighter too. What kind of headset is it? Whats the chain.s? and do you have a seat clamp listed?

Aren’t the On-One carbon forks not that light? Kingdom Bikes are a fair old bit lighter IIRC. Or some Pace RC31s?

iDave- no real reason but if you can, why not? I was surprised how light that came out at for £1300. Tomacs X 29er came in at 16.5 Lbs but costs close to $4000!

Righty, I’ve done pretty much the same thing as shown in this terrible pic

Basically I think you’ll do well to get sub 17lbs. I’ve got the much lighter Storck fork on mine and lighter wheels and its still a fraction over 18lbs. Unless you’re riding a small, I don’t think sub-17 is realistic

That looks amazing! Are you running Alpine wheels? I probably would be running a small.. How does the bike feel to ride? Ive never ridden anything below 25lbs.

A small and you might just do it – that’s a large which is why the wheels look stupidly small

Basic spec is:

Whippet frame (20)
Storck Rebel fork
Tune hubs on Stans 355s
Middleburn RS8 cranks
WCS post, stem, bar ends
Syntace bars
FRM Ti seatclamp
Magura MT8 brakes
Gobi

Surly chain tensioner with ceramic alloy jockey wheel. I did buy the SS drop outs but couldn’t get them to work. They needed chain tugs (which I also had to buy as the ss dropouts don’t have them built in) and it was just a faff. Weight wise, with the tugs there isn’t much between them and the tensioner

To ride it feels pretty good. The forks are pretty comfy which helps, although this will only ever be used for >=2hr races. I wouldn’t want to do a trail centre or Enduro on it. Its fast though, and you notice the lack of weight on hills.

I’d change ProII hubs to ProIII running notubes will save you lots of grammages!! 😆 And as said before RC31’s are the weight weenie choice for good value:weight ratio. 17lbs that’ll be fast!!

For my 2p worth:

Rocket Rons 2.35″ at approx 510g each or
Fast Freds 2.0″ (not Furious) at approx 360g each.
Conti Supersonic Tubes at 100g each.
YBN Hollow Pin chain at 260g for 116 links (you will need ~92 links).
Eggbeaters with ebay Ti axles = approx 240g a pair for £60 all-in.
KCNC Scandium Flat Bars at 120g.
KCNC Disc Rotors at approx 75g each.

Complete with a wash-through of titanium bolts and you are done, or at least your £1k will have gone!

The rest is all within striking distance of your expected weights, but you may de dissappointed when you weigh some purchases!

PaulD

All great info. Thank you very much! This is my first weight weenie build attempt. Certainly a lot of food for thought. I will need to run flats though (plus ive already got the pedals). KCNC seems to be a clear choice for a lot of people when ive been looking.

save some £ and 130g by going for A2Z hubs rather than Pro 2.

save 30g(?) by going for Stan’s Alpine rather than Crests rather take the strength myself, though.

A lot of good advice there but some is a bit misleading.
Firstly frame size has little bearing on an overall build weight. Sure it makes a difference but not that much, Small frame will weigh less but its only 100grames or so. Check out the Weight weenie site, many of the silly light bikes are large or even XL.

Spec sheet build and true build rarely tally, In my experience they can go either way but normally TRUE weight is more than spec sheet weight as the little inaccuracies add-up. As do the little bits like cables nuts bolts and spacers.
Tubeless is OK. but for weight weenie on a bike that is going to be used I would go for lightweight tubes every time. Thin walled tyres and tubeless are bad news in my experience.
Take a look at KCNC stuff, bars stems post etc. Very light weight and not silly money.
Use TI bolts wherever you can, a fair bit of weight can be had there.
Ebay for cheapo China carbon saddle, just type in Carbon saddle and look at the cheapest, watch for the postage cost though. Most are around 95Grames and can be had for £35 posted.
Forks, check out ebay for used Pace Carbon rigids. The ones marked ‘’Ti inside’’ are even lighter.
A sub 17lb HT build is fairly easily obtainable these days, rigid and S/S is obviously even more so.
Light bikes do make you faster in most cases though, especially up hill. You will find a whole new world opens up, not all good though, more rider input required going downhill + it can get expensive.
It does take a fair bit of planning though and can become addictive and did I say very expensive.!

Anyone used those Chinese carbon wheels? They look pretty light, just wondering if I should go for a set?

I’d go for a Sub 20lb bike and buy some pies with the change

Or change the spreadsheet to show 1 decimal place and be happy that it wasn’t over 17 lbs 🙂

Interesting stuff ! I think i’ll crack on but change some parts over to KCNC and Chinese carbon. Those Chinese saddle look awfully uncomfortable. Thanks for all the input guys! Will also try and stick to my original budget. Be interesting to see how it turns out. I’ll post up the final results. Please keep chipping in with info if you have any. Thanks all 😀

Re-cheap Chinese,
They are not actually that light. Not sure why as the rims should be. Must be the spokes and hubs.

A light wheelset these days is sub 1400g. Sub 1500 can be built up for less than £250 with A2z hubs and CRC discounted Stans rims.

It can be very rewarding planning and building light bikes.
Try not to take it too seriously.
I know a guy who uses Carbon chain rings and is now building a Carbon 9sp cassette. I think thats a few steps too far, and will surely break.

Light parts can be reasonably priced. The trick is know what everything weighs (Buy some digital scales) and buy based on grames saved per £.
Dont get caught up in it too much. A good lightweight stem is say 130 grames a Ritchey WCS Alloy is a good one and can be had for around £35. A Carbon Stem (Extralite I think) sold on ebay recently for £180 it was not even new, it weighed in at 92Grames. So 38g saving for £145. Not a good buy in my view.
Tyre choice is a good one as well, Maxxis do some silly light ones at less than 285g but they are like inertubes and not really usable. Rocket rons in 2.1 are a good choice if its not to flinty or rocky.
Lastly re-the carbon saddles, I have tried lots and the ones without he big central cut-out are not too bad, pretty good actually. I prefer my one to an SLR. Prone to break if not treated well though.

I would use Continental X-king supersonic tyres at 440g each and their lightweight MTB tubes. Also the new CB eggbeater 3 or Eggbeater Ti pedals are lighter and now have bearings that last.

Also don’t forget rim tape. Some of the OEM stuff is quite heavy. Velox Jante de fond is some of the lightest about and is cheap.

For wheels I would go with Ryde Edge rim (371g -claimed each for race/sub 85kg riders) Sapim race spokes and XTR/hope pro 3 hubs with 32 spokes. That would be pretty light. Although if the A2Z hubs are lighter still I would go with them. Alu nipples can save some real weight too but to have a habit of seizing.

For post and stem I would go with Thomsen Masterpiece, as light as sensible priced carbon but made of metal.

You might want to check the weight of the whippet – think its 1300 without dropouts, so closer to 1500g overall. Think the alu/carbon fork is around 900g too?

Velox Jante de fond is some of the lightest about and is cheap.

or a wrap or two of electrical tape.

I reckon you can generally add 10% for compound error and what not on a spreadsheet weight.

You’ll struggle with those wheels, mine were 1585g. I’ve also got some A2Zs with Podium rims and Revolutions that are 1246g with yellow tape and valves. Cheap too. 72kg weight limit though, Alpines would add c100g. Fit Rocket Rons or Ron/Fred combo, tubeless.

Check out Mt Zoom for bars and things, excellent value and very light. XCRacer do some ti bolts that are good if you go down that avenue too.

Don’t get Egg Beater 11s (unless you have bags of money) get 3s and some ti axles on eBay.

You can get lighter seatposts – I’ve got some brand new New Ultimate ones which are c130g for a 30.9×350, no idea what size the Whippet takes, drop me a line if you’re interested.

XTR cranks are lighter even than XX, although there are bigger savings to be had here – check out Lightning.

Point One Racing do the lightest headset spacers.

X10SL chains are light – get one on eBay from Taiwan.

SLRs are 135g (as said) – but I’d look at carbon jobs if this is an exercise in hanging a bike on the scales, rather than actually riding.

Check out Experimental Prototype for light chainrings, I’ve got a ti one and it’s great.

Devil’s in the detail then. Mt Zoom one piece bolt/top cap, alu bolts in your levers, bottle cage, chain guide etc. Alu backed pads, KCNC rotors (160/140).

On One CNC 70mm stems (£20 when I bought one last month) weigh 91g and then another 22g for the six bolts – so if you Ti them, that would be 102g all in.

I’d go tubeless but use slightly heavier/stronger tyres (for same weight as a tyre/tube), and low psi for a bit of comfort.

And even when you’ve added everything into the spreadsheet, add a pound. But second Nick and the MT Zoom stuff (look on ebay).

Be careful, it can all get a bit anal…, do remember to use the thinnest possible tie-wraps and cut then fully down 🙂

New Ultimate gear is excellent, but seemingly impossible to find, even over here in the Nordics

One-One carbons are heavier than that. Exotic are a bit lighter but if your going that light your looking at Niner or Pace RC31 Ti’s.

And flange…that’s gorgeous mate. Love it.

My On-one carbon forks with a cut steerer tube was surprisingly heavy. It was around the 900-950g mark.
The Pace RC31s on the otherhand were very lightweight but had a fair amount of fore/aft flex under heavy braking.

I was the uk distributor TSC – I’ve got flat bars in alu and carbon plus a load of seatposts in various sizes. Not got a 34.0 for the Trek, but drop me a line if you’re after anything else, I’ll see what I’ve got!

Agree it’s nice stuff though, too expensive over here now, £200+ for a post is too much I think!

ive got an njee recommended experimental prototype chainring for sale

4 arm – 27t

Ooh that’s a lot of money njee! Pity as they make good wheels, posts, stems, and bars, good luck with that though

experimental prototype is Swedish and do some crazy stuff for Cannondale Lefties, here, and here

Ooh that’s a lot of money njee! Pity as they make good wheels, posts, stems, and bars, good luck with that though

I was the distributor – now Axel Imports. Basically I wanted a seatpost for me (cheap) and I ended up being the distributor. Basically bought a job lot of stuff, used half of it myself, and sold a few bits. Wasn’t really a sustainable business model, I think they wanted someone who would sell it more pro-actively, not unreasonably!

once you start being a weight weenie…….

There was a snapped AX post on Weight Weenies, the wall thickness (or lack of it!) was mental!

theres broken parts of everything all over the web, everything breaks if you hit it hard enough,

that one went back as it was too short, i got an MCFK post yesterday, the wall thickness at the bottom is very thin, i can flex it by squeezing, there is a specific clamping section on the post 70mm or so further up where the carbon is a lot thicker

There’s some absolutely fantastic info in this thread. Well done all!

One thing to beware when going down the weight-weenie route is that you can end up with an MTB that while very light, is bugger-all good at doing what its suppose to do.

Mine is 25lbs, which may be way over what you are aiming at, but this includes; pedals, lights/brackets/switches, front mudguards, 3×9, big discs, 2.35 tyres, 711mm bars, proper size saddle, a 20″ frame and 140mm forks. Consequently it pretty much is ‘all mountain’, to use that horrible phrase and is often ridden all day. But to get it down to this has taken a lot of effort (and cost).

theres broken parts of everything all over the web, everything breaks if you hit it hard enough,

Wasn’t meant like that at all – was merely giving it context. The guy had been using it for ‘cross, not what I’d use a 70g seatpost for I must say!

The MCFK stuff looks good, I just can’t bring myself to spend that much on parts! NU was my limit!

i figured if id spent £200 quid on a reverb, then £200 quid on a carbon post was ok, justification in everything 😆