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:
The Building Process
• 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.
• 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.
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.
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.
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.
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.
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