Taking a Knife to Brand New Frames to Build the World's Lightest 29ers
By the end of the 2016 season, I thought it was time to start looking for two new cross country bikes. Scott had just released their new Scale and Spark models, and coming from an old Scott Scale SL, this was a natural choice. Having a look at the weight I did some rough calculations based on previous experience and the components available at the time, and it seemed possible to build a hardtail below 7kg and a full suspension bike close to 8kg. The project's countless delays and months of waiting meant spare time - Spare time to think about ways to take these projects even further.
I'm sure many can relate to the phrase: "Well... That escalated quickly!" when it comes to building bikes. Here we are, a year later with the lightest 29ers ever built. But first, to get a few things out of the way:
Some Disclaimers
• No, these bikes are not for everyone. They have a 85kg / 187lbs rider weight limit.
• No, they are not dentist bikes. In fact, they are so expensive that most dentists would complain in the comment section.
• No, they are not show bikes. They are used for daily training, racing, and lots of fun.
• No, they are not dentist bikes. In fact, they are so expensive that most dentists would complain in the comment section.
• No, they are not show bikes. They are used for daily training, racing, and lots of fun.
• Yes, you could probably break them "at your local trail." They are purpose built XC and marathon bikes.
• Yes, the stems are long and the drop is big. This is how I want to sit.
• Yes, Furious Fred tires are the worst. But, they are there for comparison and to show what's possible.
• Yes, the stems are long and the drop is big. This is how I want to sit.
• Yes, Furious Fred tires are the worst. But, they are there for comparison and to show what's possible.
The Building Process
After the frames were ordered from Scott, a lot of time was spent on research about what was available, and to come up with my own ideas and having them realized. The goal from the very beginning was to build super light, but without compromising strength and durability too much. The hardtail needed a real fork with lockout. Same thing for the fully, and both needed a big cassette and chain ring. They would have to be usable, and hold up to both training and racing. Another important goal was to keep them looking like normal mountain bikes. Along with that, a big part of the fun with building bikes is making them look great.
Warranty already void...
Putting a knife to brand new frames worth €10.000 is a strange feeling to say the least. But, I don't really like orange. Most of the paint and primer was removed using knifes, then I sanded off the rest, finishing with finer and finer grit paper. As many of you know, the paint serves as UV-protection for the carbon resin. So after this the frames are regularly treated with UV-protective wax. A good thing that comes from this, is that raw carbon is a lot harder than paint, so after being waxed, the surface becomes extremely slippery. Dirt practically falls off by itself. Stripping carbon frames is not difficult work, but very time consuming. More than 90g per frame was a good saving though, and well worth the slightly traumatic experience. Using carbon derailleur hangers and cable ports from Hopp Carbon Parts dropped the weight even further.
Paint removal, followed by sanding and polishing.
For the Scale, the fork was stripped of paint, then the lowers and crown were sanded and polished. The magnesium lowers require some maintenance to stay shiny, it depends a lot on what environment the fork sees, but to stay shiny, a polish at least once a month is required.
A ShiftUp Light Cartridge was installed, it features only lockout and is custom tuned for each rider, along with their carbon axle. Air cap and volume spacer from Hopp Carbon Parts. All this brought the weight down to 1239,4g.
36,5g vs 15,9g carbon hardware. Tuned Twinloc remote.
For the Spark, not much was done to the fork, but a lot of work was put into the remote system. The Scott Twinloc remote is used to control both front and rear suspension, and already is quite light. But, by modifying it to a matchmaker mount, along with some other tuning, the setup got even lighter and also cleaner looking. All connections were then made to work with PowerCordz housing and synthetic fiber cables, which is also used for the shifting system.
197g and still going strong after almost 2000km.
While a Shimano derailleur is slightly lighter, I like the ergonomics of the SRAM shifter a lot better. So XX1 was the obvious choice, but with a starting weight of about 245g there was a lot of work to be done. Thanks to a new inner cage plate and pulley wheels from Extralite, a parallelogram from Hopp, and a good deal of old-school Dremel work by me, I got the weight down to 197g. It could actually be a lot lighter by using more carbon parts, but this was good enough for the Spark.
The Acros AGE rear derailleur.
For the Scale however, where I really wanted to push the limits, I got a Acros AGE hydraulic shifting system. First of all - it looks amazing. All that CNC-work actually is a quite refreshing look for a derailleur. To match all the other polished parts, it was disassembled and stripped of anodizing. Performance wise. this system was actually one of the best surprises in a long time. Ergonomics are great and the shifting is extremely distinct and precise. Without doing any tuning, the weight of the complete system is just 281g.
Custom made by Berk Composites
To save some more weight and make for an even cleaner looking setup, the Scale got a one-piece seat and seat post combo. It weighs just 161,9g and could have been made lighter still by bonding the seat directly to the post without using rails, but I prefer to have the added flex for comfort. Believe it or not, a carbon seat with no padding can actually be really comfortable. I'm waiting for some puns about this in the comments though...
When light just isn't light enough: Bonded handlebar and stem (right).
The handlebars are Schmolke Carbon TLO in 720mm width with MCFK carbon stems. These already are some of the lightest combos you can get, but I let Mattias Hellöre bond the bars directly to the stems to save another 10g per combo. And almost as important, it looks extremely clean. Weight is just 174.0g for the 90mm, and 176.5g for the 100mm extension.
Other components
I could go into details and pics with pretty much every single thing on these bikes, but to sum up the rest:
• Custom made silver Extralite hubs, hand sanded and polished; Sapim CX Super spokes; and sanded 77Composite clincher rims make for a 1086,8g wheelset.
• For the second wheelset, the same hubs and spokes are used, but laced to DT Swiss XRC950T tubular rims - 1169,3g for the set.
• Trickstuff Piccola brakes are used for both bikes. One set in custom silver. Light but extremely powerful. Much better than, for example, Shimano XTR.
• Chainrings from Garbaruk Components, with the one for the Tune cranks being custom made.
• Bolts, axles and headsets from Extralite.
• The rider weight limit of 85kg is set by the pedals, seat- and handlebar-combos. The clincher wheel set has a 100kg limit and the frames a 125kg limit.
Result: Scott Scale RC 900: 6.22kg/13.71lbs
Overall Weight Vs Tire Selection:
• Schwalbe Furious Fred LiteSkin - 6.22kg / 13,71lbs
• Schwalbe Rocket Ron LiteSkin - 6.59kg / 14,53lbs
• Schwalbe Rocket Ron SnakeSkin - 6.73kg / 14,84lbs
Result: Scott Spark RC 900 SL: 7.33kg /16.16lbs
Overall Weight Vs Tire Selection:
Schwalbe Furious Fred LiteSkin - 7,33kg / 16,16lbs
Schwalbe Rocket Ron LiteSkin - 7,70kg / 16,98lbs
Schwalbe Rocket Ron SnakeSkin - 7,84kg / 17,28lbs
Riding the World's Lightest 29ers
First of all, it's one thing to imagine lifting a bike this light and something else to actually have it in front of you. I could've made a compilation video with peoples facial expressions and comments when they got to lift the bikes, just for laughs. Everyone knew the weight, but was still more or less in chock feeling how light they really are. Same thing goes for riding them. A good friend took the Spark for a ride, and his first comment was that it was more like accelerating on a high end road bike than on a mountainbike. He even noticed how the steering felt lighter. Generally a 10kg fully is a light and great bike, but this is a different kind of beast. Same thing goes for the Scale.
The one word I would use to describe the ride characteristics is responsive. Low rotational and overall weight makes technical climbing a lot easier, and same thing in for example race situations like having to accelerate hard out of a corner to keep up with a rider in front of you. And of course the low weight helps on long climbs as well. They are simply very enjoyable bikes.
You might think that these bikes would be super nervous going downhill, but actually not. A cross country bike will always be less confidence inspiring than a trail or enduro bike, but this comes down more to geometry than weight. And having that seat a mile high in all situations. The Scale and Spark is a good chassis, and especially the Spark with its relatively low bottom bracket really rides quite well going downhill too. So just for fun I put some flats on it and a dropper, and took it to the bike park one afternoon. No explosions of carbon, no issues.
First of all, it's one thing to imagine lifting a bike this light and something else to actually have it in front of you. I could've made a compilation video with peoples facial expressions and comments when they got to lift the bikes, just for laughs. Everyone knew the weight, but was still more or less in chock feeling how light they really are. Same thing goes for riding them. A good friend took the Spark for a ride, and his first comment was that it was more like accelerating on a high end road bike than on a mountainbike. He even noticed how the steering felt lighter. Generally a 10kg fully is a light and great bike, but this is a different kind of beast. Same thing goes for the Scale.
The one word I would use to describe the ride characteristics is responsive. Low rotational and overall weight makes technical climbing a lot easier, and same thing in for example race situations like having to accelerate hard out of a corner to keep up with a rider in front of you. And of course the low weight helps on long climbs as well. They are simply very enjoyable bikes.
You might think that these bikes would be super nervous going downhill, but actually not. A cross country bike will always be less confidence inspiring than a trail or enduro bike, but this comes down more to geometry than weight. And having that seat a mile high in all situations. The Scale and Spark is a good chassis, and especially the Spark with its relatively low bottom bracket really rides quite well going downhill too. So just for fun I put some flats on it and a dropper, and took it to the bike park one afternoon. No explosions of carbon, no issues.
 | ...The Spark, with its relatively low bottom bracket, really rides quite well going downhill too. So, just for fun, I put some flats on it and a dropper, and took it to the bike park one afternoon. No explosions of carbon, no issues. |
Although the bikes was just recently finished (if they ever truly will be...) the Spark has already been ridden almost 2000km and the Scale a bit less. So, most parts are already very well tested, since I always had some version of one bike up and running. The only parts not yet ridden are the handlebar combos and the seat/seat post combo. So with both bikes finally complete, I'm really looking forward to the 2018 season, to forget about building and just ride the shit out of them.
What's next?
Not much, except riding. Could they be made lighter? Yes, about 200g for the Scale and even more could be dropped on the Spark. Since the project has taken so long to complete, a few new and lighter options are available like for example rims. Also more tuning work could be done, like having the Acros system made fully out of carbon by Hopp. But, with new wheels and so on, this would be some stupidly expensive 200g to save, So, without any sponsors or partners, this will be it for now.
So a long, cold and dark Swedish winter without any project at all? Of course not, soon a 2018 Scott Genius Tuned frame set will arrive. It won't be fully focused on weight, but should still be a pretty cool build with some custom work. Feel free to have a look at my Instagram to keep up with that project and to see more of these bikes in action next year. And also it might help explain the shorts and flat pedals. Cross country could use some more rock'n'roll and hopefully there'll be a lot of laughs along the way.
Warning: most of these modifications will void your warranties. If you think the polished fork looks awesome, remember that you will need to keep polishing it or else it will oxidize and turn matte. Also, stripping a frame will take longer than you expect, so don't blame me when you want to give up. And most importantly, remember to read Pinkbike and listen to Motörhead on a regular basis. - Gustav Gullholm
Not much, except riding. Could they be made lighter? Yes, about 200g for the Scale and even more could be dropped on the Spark. Since the project has taken so long to complete, a few new and lighter options are available like for example rims. Also more tuning work could be done, like having the Acros system made fully out of carbon by Hopp. But, with new wheels and so on, this would be some stupidly expensive 200g to save, So, without any sponsors or partners, this will be it for now.
So a long, cold and dark Swedish winter without any project at all? Of course not, soon a 2018 Scott Genius Tuned frame set will arrive. It won't be fully focused on weight, but should still be a pretty cool build with some custom work. Feel free to have a look at my Instagram to keep up with that project and to see more of these bikes in action next year. And also it might help explain the shorts and flat pedals. Cross country could use some more rock'n'roll and hopefully there'll be a lot of laughs along the way.
Warning: most of these modifications will void your warranties. If you think the polished fork looks awesome, remember that you will need to keep polishing it or else it will oxidize and turn matte. Also, stripping a frame will take longer than you expect, so don't blame me when you want to give up. And most importantly, remember to read Pinkbike and listen to Motörhead on a regular basis. - Gustav Gullholm
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Just a regular guy and PB user since 2003, and it's honestly been my main news source ever since (and the comment section is always hilarious of course), so it's both surreal and awesome to see an article about my own work on the front page!
And thanks for all the comments, seriously! Neither me nor my pedal pistons are used to this kind of attention.
Thanks
I know these two steeds are expensive, but out of curiousity, how much did each really cost to get to this level?
ya, ok.
I'm kidding, those bikes are insane dude congrats, and the attention to detail like rAtty says is insane
You've clearly accomplished your mission as weight-weenie, but if your greater goal involves adding *speed* then you're missing some very low-hanging fruit!
*Gets pic throwing a fat table *
1 - Ride a 26" XC
2 - Ride a 27.5" XC
3 - Ride a 29" XC
4 - Read your comments again
It has to be light but it has to be a good ride too, balance is essential. Here he didn't compromised the rolling capability and even improved the handling. 26" suck on roots sorry...
I showed him this Scale and he wasn't overly impressed. Also, he noticed that there's no bell on the handlebar. What kind of bike doesn't have a bell!??
It looks so professionally done, people are going to be calling up Scott asking about his model Scale and Spark only to come to find out that Scott doesn't have these specific bikes as they were custom done. haha
Now, back to my heavy over weight Scott Genius
A little bit envious about that though, my Genius frame set is still a month away and the bike won't be finished until spring. Can't wait though!
I'd be super stoked to see what you can achieve with the all the Genius as well!
I'll be uploading pic on my user profile here, and of course you can follow me on Instagram too.
Had a look at your Genius now, good looking bike man!
Thanks for checking out my ride as well it's a respectable 26.06lbs for a 150mm full suspension bike but if I had the extra loot I could drop it down to 25ish pounds if I swap out the cranks for a RF Next SL and a lighter weight cassette like the e13 9-44t cassette. But for now I'm happy with the current set up.
Definitely can't wait to see your new Genius project!
4 times alone on this article!
Cheers
Craig
I'll never forget the day I picked a 4700gr Look road bike from the floor...the feeling was like when you pick up a box that you think it's full and it's empty. Mindblowing.
Despite being more of an enduro guy I'm a weight weenie at heart and I can spend hours figuring what the lightest build would be! Here are some thoughts that might have to be taken with a grain of salt as weight is not the only factor:
- why go for a Scott scale instead of an FRM Anakin? ( I believe the frame + seatpost + stem + headset comes at 950g)
- AbsoluteBlack manufactures absolutely porntastic components. Honestly the hottest CNCed chainring I have ever seen ( and I have a kcnc spiderweb) and the lightest disc rotors i know( ~40g I believe).
- If you're really going hardcore, the german A.Kilo is a fork that weights ~1.0kg (suspended).
But here the bikes are absolutely stunning and remind me of that insane build Scott had on display when they introduced the then new Genius. Big up for the Schmolke, Trickstuff and Acros component! ( Still don't understand why hydraulic shifting never took off). You sir are a hero.
- The FRM seems like a good frame but the Scott is actually lighter. Also I prefer the looks of the Scale.
- Had a look at Absolute Black for sure, especially since they used to make the DM chain rings that came stock on the Tune cranks sets. I really like the design of the Garbaruks though, and they were super helpful.
As for the disc rotors, unfortunately their 160mm isn't 40g. The ones I use on the Scale are a pair of old Ashimas and about 65g each. They can be a bit sketchy but the Trickstuff brakes really are that powerful and easily lets me get away with running them.
- Tried to research German:A but it was hard to find reliable information about it. Weight seemed to vary a lot, and if you want the Lockout option it becomes almost around the same weight as my tuned Fox. Really wanted to go with a polished for too.
Agreed on the part about the hydraulic shifting. Of course it's expensive, but so good that I kinda want a set for the Spark too but not available anymore. Once again, thanks for your questions and comment.
Great work, You proved lots of stamina in the process
I think all this is patented, acros buying the then startup meant they got away with the tech. Though, i have no clue how it shifts on terrain but the triggers are the best I got my hands on! I believe they even used to make it in different colors, like the old x-0 group.
Stevie Wonder?
But don't you thing the reedres here would be interested to have a look at your old weightweenie Trek Session also? ;D
Cherrs // L
- Where did the 85kg weight limit come from given that these appear to be a bunch of one-off parts especially with all the sanding/polishing?
- How'd you sand through the black paint on the frames and not sand into the carbon since they're both, well, black? Normally when sanding carbon, getting black stuff on your sandpaper says it's time to stop. Did you hit white epoxy behind the paint and above the carbon?
Again, not trying to troll. I ain't gots time for that.
- The weight limit comes from the ti-axles in the pedals, and both Schmolke Carbon and Berk offer their products in several options, depending on how strong you need or want them to be.
- There was a lot of primer used on these frames, and the primer is clear/white. So quite easy actually. It's just that the tubing really is paper thin in some places, so still felt the need to be extremely careful not to go too deep.
I remember it was a lot of work but there was no real risk of damaging the frame. I didn't any machine, only paper and hands though. But as @bicyclerider mentioned the primer and paint are pretty distinctive from the actual carbon, and the carbon is much harder to scrap off than the paint ( goo thing carbon is strong).
Honestly, the first grind was the hardest.
I mean that even by ridding only on dirtroads, you always risk to fall, a slide on your side or something like that.
So,
how all those parts (and the frames) hold up against direct impact on rocks and momma earth?
Thanks.
UncaJohn
Love it all.
Since you already shaved your legs...
Love the dremel, knife, sanding and general f*ck warranty attitude though.
Would you be so kind to share installing as well as build thread;
Best regards,
Nick
Burn the heretic!