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PostPosted: Wed Sep 23, 2009 8:52 pm 
Deputy National AEC
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Joined: Wed Jun 04, 2008 4:43 pm
Posts: 5169
Location: Cumbria, England.
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.

Image
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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.

Frame:

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.

ImageImage

Forks:

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.

Drivetrain:

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.

Tyres:

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.

Controls:

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:

Frame: Alpinestars Cro-Mega EOS 1992. Tange double butted tubing with investment cast alpinestars dropouts

Fork: Alpinestars ODS rigid. Cro-moly unicrown , 28.6mm straight blades, forged ends and 1 ¼” steerer.

Headset: 1 ¼” threaded, silver.
Stem: Alpinestars 1993 1 ¼” 130mm +5 degree. Cro-moly with titanium finish.
Handlebar: Carbon Fiber 560mm
Grips: O'Neal Azonic Thin Grey
Barends: Answer Hyper-Ends

Brakes: Shimano Deore Disc
Brake Pads: Shimano
Brake Cables: Shimano Hydraulic
Brake Levers: Shimano Deore

Rear Chainring: Da Bomb 9 To 1 PRO Single Speed Kit C/W 17 and 18 speed rings
Chain: SRAM PC 7X Nickel Singlespeed Chain
Chain Tensioner: Blackspire Stinger Chain Tensioner BB type
Cranks: Truvativ Hussefelt 175mm ISIS.
Crank Bolts: Truvativ
Front Chainring: Truvativ 32 tooth
Chainring bolts: Truvativ
Bottom Bracket: FSA Platinum 68x113mm ISIS
Pedals: Shimano PD-M737 SPD

Hub Skewers: Shimano Deore
Rims: Mavic XM317 Disc Black
Hubs: Shimano Deore 6 Bolt
Nipples: Brass
Spokes: Double Butted Black
Tyres: Panaracer Fire XC 26 x 1.8”, steel band.
Tubes: Continental 26”, presta valve.

Saddle: O'Neal Azonic Sprint, Cro-mo rails
Seatpost: Kalloy 29.4mm, silver.
Seatpost Binder: Alpinestars alloy in silver c/w alpinestars USA signature quick release.

Mudguard: Crud Catcher ZX, Clear.

So whats your thoughts gents?


Last edited by sinnett177 on Fri Oct 09, 2009 9:01 pm, edited 2 times in total.

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PostPosted: Wed Sep 23, 2009 9:30 pm 
Lincs AEC
Lincs AEC

Joined: Fri Sep 07, 2007 8:34 pm
Posts: 12314
Location: Branston, Lincoln
sinnett177 wrote:
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.

Drivetrain:

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.

Mudguard:

So whats your thoughts gents?


Sounds like you have most of the SS points covered Mark. Keep it rigid at this helps keep weight down. I am on my second SS, and this time have put bar ends on which have proved to be a perfect, effective and may even say essential addition.

Gearing wise, I suggest 32x15. I am running this on my S-Works and so far it is perfect. Yes, I spin a bit on the flats, but it is easy to keep gunning on the ruff stuff and copes (so far) with all the hills I have tackled. Did a hard 3hr ride on Sunday on it too, with no problems. I ran a 32x18 on my last SS, which was great in the mud of winter, but very undergeared in the dry.

Mudguards.....ehhh :?

Good luck and enjoy. If your like me, you'll enjoy it and keep it.


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PostPosted: Wed Sep 23, 2009 9:44 pm 
Old School Grand Master
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Joined: Mon Nov 20, 2006 10:12 pm
Posts: 4439
Location: Barry
If your fork is curved a disc mount is probably a bad idea. Even if it is straight you may have problems.

I know Bob Jackson wont weld a disc mount on curved forks...


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PostPosted: Wed Sep 23, 2009 11:36 pm 
retrobike rider
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Joined: Mon Apr 30, 2007 12:31 pm
Posts: 2489
Location: ManchestOr
reanimation likes this.


---

Hey this is great news!

So glad you are reunited and also that you are chopping it about n building summat fresh. 8)

Forks situation is a bit of a mare though. should be plenty of modern forks that could go on instead though... ? :idea: thinking of CF stuff or Trials forks, or even the DJ skinny pants lot like to keep the front end down, sadly though going this route you're lumbered with a 1 1/8 headset again. hmm...
Custom would ruin your budget would it? :idea:

gearing, try guess what gear you'd ride in at the mo and try stick with it see how it feels resisting that klunk-change, devil makes work for idle thumbs! :D My super heavy 38-16 was a bit mental, but i'd give a 36-16 a shot again and that's what's fitted, 32 or 34 -16 more sensible, depends on terrain and you. bet you are looking lower than 16 with a 32.

Good luck, gonna be ace this. :)


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PostPosted: Thu Sep 24, 2009 8:07 am 
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Joined: Thu Jan 01, 2009 1:40 am
Posts: 590
Location: Christchurch, New Zealand
CTK wrote:
If your fork is curved a disc mount is probably a bad idea. Even if it is straight you may have problems.

I know Bob Jackson wont weld a disc mount on curved forks...


That sounds like a challenge! :roll:


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PostPosted: Thu Sep 24, 2009 11:15 am 
retrobike rider / Gold Trader
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Joined: Mon Jun 22, 2009 11:09 am
Posts: 9399
Location: Devon
Awesome.

If that is the frame you are using it looks amazing in stealth black.

Can't wait to see this finished.


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PostPosted: Tue Sep 29, 2009 8:13 pm 
Deputy National AEC
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Joined: Wed Jun 04, 2008 4:43 pm
Posts: 5169
Location: Cumbria, England.
Frame

So the frame is back with me and I’m delighted it’s back. After all the stresses and strains it took to build last year, it has a special sentimental value to me. Thanks once more to Kingcutter for allowing me to have it back.

Image


Metalwork

So after much thought I’m slowly concocting a plan of where to go with it. I really looking to show off the design of this frame as best as possible, thus I going to go as simplistic as possible by removing all unwanted features. These include cable bosses, traditional mudguard mounts, e-stay mounts and most radically the rear mech hanger (I did say I wouldn't be shy in chopping it). The rest of frame will be smoothed by filing down the rougher welds and using filler on areas of pitting and denting (including the dent in the seat tube for the e-type front mech to sit).

Rough welds to be filed down and smoothed around the rear disc tabs:
Image

Cable bosses for gearing to be removed:
Image

E-type mech boss to be removed and dent for mech to be filled and smoothed.
Image

Factory welds to be filled down lightly to smooth the finish:
Image

Forks

The forks are the original 1992 cro-mega LX forks. They are tiny bit less oversize than those used on the other 1992 e-stay models but equally nice looking. They are a 1 ¼” threaded steerer with totally straight blades, thus I’m very hopeful that a bike builder will undertake the job of adding International Standard disc mounts to them. The canti mounts will then be removed to give clean lines.

Image
Image
Image

Paint

Unless a set of 1992 graphics surface in the meantime, the paintwork will be in the colour scheme of the 1991 bikes. The colours will be those of the year which were black, bright yellow, bright pink and alpine white, I’ve no idea what order they’ll appear in yet but the middle section will certainly be white.

My 1991 cro-mega DX demonstrates the 91’ colour scheme:
Image

Drivechain

A quick trip to the CRC website today and my drive chain is complete. I’d already purchased a Truvativ Hussefelt SS crankset from the forum c/w ISIS BB and 32t ring.

Image

So to finish off the drive chain I purchased the following:-

- Da Bomb 9 To 1 PRO Single Speed Kit C/W 17 and 18 speed rings.
Image

- SRAM PC 7X Nickel Singlespeed Chain
Image

- Blackspire Stinger Chain Tensioner BB Type
Image

The stinger chain tensioner should allow me to dispense with a rear mech type chain tensioner and hence I can remove the unsightly mech hanger. Thank you to zigzag for the inspiration after seeing his SS Specialized Hardrock:
http://www.retrobike.co.uk/forum/viewtopic.php?t=63010


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PostPosted: Thu Oct 01, 2009 12:23 pm 
retrobike rider
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Ah, I see, I thought with the works getting done on the F&F you would be using slotted drop outs, but seeing the design of the fork like rear drop outs the only way to do that would be bigger fatter slotted dropouts added. possible but potentially uglier.

Coming together though, great :)


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PostPosted: Thu Oct 01, 2009 1:58 pm 
retrobike rider / Gold Trader
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Liking the project but never diss Alfa Romeo's dude!

:lol: :evil:


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PostPosted: Tue Oct 13, 2009 10:06 pm 
Deputy National AEC
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Joined: Wed Jun 04, 2008 4:43 pm
Posts: 5169
Location: Cumbria, England.
Forks

Sent the forks off to Bob Jacksons Cycles in Leeds for disc tab, cable guide and the canti bosses removing, much to my surprise and 4 days later they're back.

Image

Image

Image

I choose not have them painted as I want the paint to match the frame when I respray it all. This means I get no warranty for the work carried out but these forks are 17 years old anyhow. As a temporary measure i'm spraying the forks black to match the frame.

On the component side, everything has now arrived with the exception of SPD's from Heathy and skewers from my wheelbuilders Merlin who forgot to pack them with my new wheels and disc brakes. Thus, the spec looks like this:

Frame: Alpinestars Cro-Mega EOS 1992. Tange double butted tubing with investment cast alpinestars dropouts

Fork: Alpinestars ODS rigid. Cro-moly unicrown , 28.6mm straight blades, forged ends and 1 ¼” steerer.

Headset: 1 ¼” threaded, silver.
Stem: Alpinestars 1993 1 ¼” 130mm +5 degree. Cro-moly with titanium finish.
Handlebar: Carbon Fiber 560mm
Grips: O'Neal Azonic Thin Grey
Barends: Answer Hyper-Ends

Brakes: Shimano Deore Disc
Brake Pads: Shimano
Brake Cables: Shimano Hydraulic
Brake Levers: Shimano Deore

Rear Chainring: Da Bomb 9 To 1 PRO Single Speed Kit C/W 17 and 18 speed rings
Chain: SRAM PC 7X Nickel Singlespeed Chain
Chain Tensioner: Blackspire Stinger Chain Tensioner BB type
Cranks: Truvativ Hussefelt 175mm ISIS.
Crank Bolts: Truvativ
Front Chainring: Truvativ 32 tooth
Chainring bolts: Truvativ
Bottom Bracket: FSA Platinum 68x113mm ISIS
Pedals: Shimano PD-M737 SPD

Hub Skewers: Shimano Deore
Rims: Mavic XM317 Disc Black
Hubs: Shimano Deore 6 Bolt
Nipples: Brass
Spokes: Double Butted Black
Tyres: Panaracer Fire XC 26 x 1.8”, steel band.
Tubes: Continental 26”, presta valve.

Saddle: O'Neal Azonic Sprint, Cro-mo rails
Seatpost: Kalloy 29.4mm, silver.
Seatpost Binder: Alpinestars alloy in silver c/w alpinestars USA signature quick release.

Mudguard: Crud Catcher ZX, Clear.

I'm hoping to have the bike built up for weekend testing. I'd like to get a good feel for it before I start chopping bits off that I might later need.


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