Cannondale Scalpel 650b

In February 2011 I bought my all time dream bike; a Cannondale Scalpel. Back then 29ers was just a Sales Guy's wet dream so this was a pure bred 26 inch Zero pivot racing machine. Raced to numerous victories on the XC world cup circuit by legend Christoph Sauser in the early 2000's and raced to victory on a rim to overall victory at the Cape-Epic by Roel Paulissen and Jakob Fuglsang. This was cutting edge technology at its best with the absolute unequalled Lefty doing the business up front and the carbon flexing zero pivot suspension at the back. The bike I bought was a second hand 2008 model frame, black carbon, with a 2010 Lefty, some super blingy Crankbrother Cobalt Black and Gold wheels and a three-by-nine SRAM drivetrain. The 2008 model did not have a BB30 bottom bracket so the crankset was a GXP Truvativ Noir piece. I christened the bike Black Mamba.

As the bike was second hand I knew the Original Owner warranty would no longer be valid and I immediately took out comprehensive insurance on the bike. This turned out to be a stroke of genius because in October 2011 the frame broke where the shock attached to the frame on a training ride. I was supper bummed at this bike cost me a ton of money!

I went out of my way to source a replacement frame and in the end the distributors of Cannondale in South Africa (Omico) and the insurance company replaced the frame with a 2011 model. These models all had a BB30 so an adapter was inserted into the bottom bracket to accommodate the GXP crank.

The bike was brilliant. The stiffness of the bike was incredible and the handling was absolutely superb. I christened this version of the bike El Capitan, mainly because of its awesomeness.

Then the whole 29er scene really got going. 26 Inch bikes were dropping like flies and my super bike's value turned to dust almost overnight. No I know that one is supposed to not care about what you ride and just enjoy the ride but in reality that is bullcrap, everybody has some connection to the bike. So here was my predicament: I could not sell the bike as I would get nothing for it and I did not really want to either but every magazine article, journalist and forum told me that I had to get a 29er. Luckily my wife also rides every now and then and I decided to buy her a Giant Anthem X29 which I could test ride every so often without having to sacrifice my Cannondale.

But a strange thing started happening. Whispers of an inbetweener size. 650b some called it, 27.5 inch others but more importantly a certain rider never stopped winning on it. When it was revealed that Nino Schurter just couldn't get a 29er to work for him and 27.5 was his size I started to take an interest. I'm on the shorter side of the height scale and at 1.7m I was a perfect fit for 650b. It was then that I started seeing posts about converting your 26inch to a 650b.

The Conversion

So I decided this was the route I should take. I started my research and at the time there was not a whole lot of info except that the Cannondale Scalpel time and again came up as a perfect fit. At the same time I also came across a lot 1x conversions for the drivetrain. I decided that while I was busy making changes I could just as well do a 1x10 conversion. 1x10? Yes 1x10. Why not 1x11, well that just cost too much, simple as that.

I started sourcing the parts. First on my list, for some reason, was a BB30 crank. I found a good secondhand SRAM S1400. For the single chainring I bought a 32T Wolf Tooth direct mount. I got a 11-36T cassette as this gave me the widest range, an XO 10 speed derailleur and an X9 shifter. I had the BB30 installed and started working on replacing the 2 chainrings with the Wolf Tooth.

To my dismay however, when I tightened the cranks the chainring touched the frame at the chain stay. I decided to make an aluminium spacer and played around with thickness in a bid to move the cranks a bit to the chain side. It should be noted that Wolf Tooth realised this flaw themselves and I see nowadays you get a specific Wolf Tooth direct mount for bikes with wider chain stays like the Scalpel. Off course this product was not available when I did the conversion but when my chainring wears out I will buy this revised one.

I found the sweet spot and the below pictures shows the chain line, installed spacer and the clearance of the Wolf Tooth I achieved.

The wheels were always going be the Stans ZTR Crest rims as I felt and still do that these are the best value x performance rims. For hubs I couldn't use the integrated Crankbrother ones, they only work as a unit. So a good friend of mine who also owns a 26inch Scalpel agreed to swap wheels with me so I could dismantle his to get to the hubs and I got the wheels built at my Local Bike Shop. One important thing that I realised was tyre choice. Luckily a pair of Ritchey Shields 27.5 x 2.1 came up on sale and I took a chance on them. I've realised through the years of riding that tyre choice is very personal. A tyre can be brilliant on paper but if they don't "feel" right you will have no confidence with them. These Ritchey's turned out to be an excellent choice. They grip very well in most conditions but still have low rolling resistance. As can be seen in the picture, they also provided enough clearance between the wheel and the bridge that connects the seat stays.

For good measure, I changed the 640mm riser bar I had to a 700mm flat bar. In the end I managed to shave nearly a kilogram of the weight, before the conversion the bike weighed in at 10.5kg (23 pounds) and after it weighed in at 9.6kg (21 pounds). This weight is race ready: pedals, bottle cages, sealant the lot.

And here she is:

Some Thoughts

I've now owned and ridden this bike in 650b guise for a year and can safely say that this is the best possible revival I could have given this piece of engineering mastery. I've read on the internet that modifications had to be made to the frame and lefty to accommodate this "upgrade" and I can safely say that I've not had to make any of these. This includes having to put spacers in the Lefty to reduce the travel and having to move the bridge between the seat stays. If you stick to a 2.1 tyre with not too hectic nobblies you will be fine. Some argue that you are left with a compromised bike as your tyre choices are limited etc etc. I disagree with this, the Scalpel is a racing machine and I would not have chosen different tyres in 26 inch guise anyway. You will have to check you shock and Lefty pressure often but this is good practice regardless. With regards to the drivetrain, I have had no problems with the 32T with 11-36 Cassette. Some would say that the ratios are not enough and yes, it is less than a 1x11 SRAM set but the price difference is so big that I could not justify it. I have not run out of gears, steep sections where I've had to dismount was because of a loss of traction more than anything else. On the overdrive side, most mountain bike races are not flat enough that I've felt a great disadvantage.

Handling is sublime, simple as that. To give an example, on a particular race I did there was a guy on an SWorks 29er that I tussled with for most of the race. On the flats I could not keep up, mostly because of my fitness, but as soon as the track turned upward or twisty I would be on his tail and pass him. The guy even commented that he just could not match the nimbleness of the bike.

To put things in perspective; a new 9.6kg dual suspension bike would set me back about R80000 ($7500), maybe even more. This bike cost me R35000 ($3000). It is worth it.