Project No. 6: alpinestars Cro-Mega SS
My aim is to build a unique single speed for use in next years UKSS championships. I’ve been watching from a far as people have pioneered this single speed mountain biking revolution, now the time has come to join in the fun and compete in this excellent championship series run by our very own Gil_m.
I’m looking for this single speed build to be several things:-
- Fully rigid (my preferred kind of riding at the moment)
- Low rolling resistance (to save as much energy on the slogs as possible)
- Brake consistently (so as not to scrub off too much of my hard earned momentum)
- Climb adequately (perhaps the undoing of many a SS bike)
- Valve for money (I’m looking for a lot of smiles per pound from this build)
- Ultimately have the character and charm of a retro steed.
To achieve this I’ll be mixing the old with the new, a situation I’m fairly familiar with after successfully completing my first Retrobike project, a 1992 meets 2008 alpinestars cro-mega XT, a ‘hotrod‘ if you will.
So for this project I taken a backwards step and tracked down my old alpinestars frame from the project above, almost exactly a year after the original build was completed. As an EOS (Elevated Oversize System) alpinestars it oozes the old school character and charm that I’m looking for. But better than that it’s already converted to accept a rear disc brake and the frame was designed purposely to climb well with it’s super short wheelbase. So by adding rigid forks, some low rolling resistance mtb tyres and keeping cost to a minimum, all my wants should be satisfied.
To refresh your memories, the frame is a 19” 1992 alpinestars cro-mega. It’s been modified with a rear disc mount, an E type front mech, crud catcher mounts and has had it’s cable mounts rearranged to suit the hydraulic cabling and top pull mech. Thus, I’m not worried in the slightest about chopping and changing the frame further. When built as in the picture above the bike had a very fine margin for getting it set up correctly due to all it‘s modifications, this is the reason why ultimately I broke the bike up and moved on, when it was right the bike rode absolutely fantastic but when it was misbehaving it was a frustrating beast, rather like owning an Alfa Romeo I believe. Fortunately I gave the frame away for karma to friend and fellow Retrobike member Kingcutter, he built up the frame to his own tastes before dismantling it many months ago. The frame has since laid dormant in his workshop, until he kindly allowed me to have it back for an equal dose of karma.
My plans for the frame are fairly simple. I’m going to de-boss the frame as much as possible. With no need for any gear cables or front mech hangers, these might as well be removed to give clean lines. The frame is currently painted in 2 pack black, this will be removed and a rattle can paint job applied. I was considering an all singing and dancing professional paint job, but I want to keep the costs down and want this to be a hands on project as much as possible. The paint job I’m hoping to achieve is based on the 1991 alpinestars design, despite this being a 1992 frame. This is for 2 reasons, firstly the 91’ design is my favourite and secondly Gil_m has the 1991 graphics loosely on file but no 92’ graphics. As I own a 1991 cro-mega DX I’ll be copying the detailing of the paint job as best as possible from that. The colour scheme is totally undecided at this time, but it's likely to bright as it is an alpinestars after all.
I have had a set of 1992 alpinestars rigid forks lying around for a while. They are 1 ¼” threaded and currently have mounts for cantilevers only. The plan with these is to have an I.S. (International Standard) disc mount fabricated on to them and the canti mounts removed. I’m going to entrust the job of fitting the disc mount to a professional bike builder, this should ensure correct alignment and a proper job.
Should be a simple enough affair, my biggest concern is getting the gearing correct. I’ve started by picking up a nice Truvativ single speed crankset up off the forum with gearing of 32t.
Wheels and Brakes:
Once the forks are converted to disc I’ll be looking to get some disc brakes for the project. I’m pursuing discs as they will provide consistent and powerful braking. With using discs my wheel choice is therefore limited to modern. Second hand may well be an option for me in both wheels and brakes, thus giving better value for money, although I’m tempted by Merlin Cycles great wheel and disc packages which are extremely good value.
I’m looking to keep rolling resistance down whilst having good grip on the loose stuff. Whatever tyre I choose will undoubtedly be a compromise, but I’m a big fan of Panaracer‘s Fire XC 1.8”. I’ve often used them on my Raleigh and love the low rolling resistance and levels of grip they give. Thus, these will be my tyre of choice in the steel band version to keep costs as low as the rolling resistance.
A bit of a mixture here involving Kalloy, alpinestars and brandless carbon fiber. I already have the Kalloy silver seat post and the carbon bars are in the mail. The stem will be a 1993 alpinestars 1 ¼” from SJS, which will hopefully fit the standard diameter bars, this is a bit of a gamble as in earlier years alpinestars used a unique bar diameter. As for a saddle I’m torn between a nice black flite or a modern saddle such as a Charge spoon.
With many gaps here's the spec so far:
Alpinestars Cro-Mega EOS 1992. Tange double butted tubing with investment cast alpinestars dropouts
Alpinestars ODS rigid. Cro-moly unicrown , 28.6mm straight blades, forged ends and 1 ¼” steerer.
1 ¼” threaded, silver.
Alpinestars 1993 1 ¼” 130mm +5 degree. Cro-moly with titanium finish.
Carbon Fiber 560mm
O'Neal Azonic Thin Grey
Shimano Deore Disc
Da Bomb 9 To 1 PRO Single Speed Kit C/W 17 and 18 speed rings
SRAM PC 7X Nickel Singlespeed Chain
Blackspire Stinger Chain Tensioner BB type
Truvativ Hussefelt 175mm ISIS.
Truvativ 32 tooth
FSA Platinum 68x113mm ISIS
Shimano PD-M737 SPD
Mavic XM317 Disc Black
Shimano Deore 6 Bolt
Double Butted Black
Panaracer Fire XC 26 x 1.8”, steel band.
Continental 26”, presta valve.
O'Neal Azonic Sprint, Cro-mo rails
Kalloy 29.4mm, silver.
Alpinestars alloy in silver c/w alpinestars USA signature quick release.
Crud Catcher ZX, Clear.
So whats your thoughts gents?