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Custom Ti Gear Box Bike
by superfly
Posted: May 27, 2009
How to build your very own Ti Gear Box Bike by Alan Hawkes.
O.K where to start, the big question is why? Well why not? I've made downhill frames before using t45 steel so I thought if I was going to build a gearbox DH bike then I may as well do something special. There is probably no advantage in having titanium over alloy but if you're only going to do it once then why not make it different?
O.K where to start, the big question is why? Well why not? I've made downhill frames before using t45 steel so I thought if I was going to build a gearbox DH bike then I may as well do something special. There is probably no advantage in having titanium over alloy but if you're only going to do it once then why not make it different?
Racing every weekend you see some sights, Big Hits with Super Monster Tee's, zero throw stems, 85 spacers under someones stem and even Wulf Sport clothing that would make your toes curl.
Luckily for you lot I still keep my eyes peeled and my old mate Alan Hawkes wheeled this little beauty past me. A quick karate chop and he was stopped in his tracks. He promised to get her polished and some pics and words how this little beauty came about..
The following words by Alan Hawkes.
I bought a G-boxx over a year ago after enquiring via Karl Heinz at Nicolai, so that was the starting point, after I'd decided on titanium the next problem was where to get the material as it can be quite hard to get the sizes you need hence some compromises.
I work in motor sport engineering, so I was lucky enough to get a piece of 60mm dia. ti tube for the down tube, which I then ovalised. The head tube is made in three parts, two rings for the headset to sit in and the center part is made from rolling up a piece of 3mm sheet ti, this was then assembled, welded, then final machined. The mounting for the gearbox is again made from 3mm sheet, folded carefully on a fly press just using eye to fit the contour of the gearbox, not easy!!
The most time consuming part was the swing arm pivots, machined from billet titanium, probably a good days work there! No CNC machines for me unfortunately. Even the seat tube had to be machined from a solid bar, if you were to make a few you could justify getting parts machined or water jet cut but for a one off it's not really viable.
The two top tubes are 19mm dia. and I even had to make a tube bender so I could get the desired angles. The actual assembly and building was not too difficult but then is my trade. The rear dropouts are fabricated from 3mm sheet with sliding alloy parts for the axle to go through.
I drew up the suspension layout on a board and made various pieces of metal until I got the desired amount of rear wheel travel for the shock length and to get a rising rate, then once that was done I could machine these parts from alloy, these are not yet really finished but I wanted to make sure everything works OK before I spend hours machining something just to make it look prettier!
So once I had all the parts all I had to do was put it all together, simple really. I made an 'L' shape jig into which I clamped both wheels at the intended wheelbase, then fitted the forks and head tube, set these at the correct angle, fitted the gearbox onto a mounting plate on the jig, then basically measured, cut, ground and offered up the down tube until it fit perfectly! Then I did the same with the rear end, then made a separate jig so I could weld the swing arm without distortion.
Refitted the swing arm then attached all the suspension parts, then made another fixture to hold the seat in the correct place and cut and bent the tube to fit between the seat tube and head tube. Then just a case of welding it all up and off for test rides.
The first proper ride I had on the bike was at the first round of the Caersws Cup 2009 so a baptism of fire really! Only a couple of minor issues with the chain really but these were soon sorted.
So that is how you build a titanium gearbox bike, I'm never satisfied so I have already started building another bike, this one is going to be more conventional though, made from t45 again and seven inch travel with single crown forks, hoping to get a lightweight downhill/freeride bike, hopefully by July, so I have a lot to do.
Alan, many thanks for your detailed words and inspiration to all Meccano players out there.
Stay Unclipped!
Si Paton.
Descent-Gear.com
Troy Lee Sprint Shorts 59.99GBP Posted
Luckily for you lot I still keep my eyes peeled and my old mate Alan Hawkes wheeled this little beauty past me. A quick karate chop and he was stopped in his tracks. He promised to get her polished and some pics and words how this little beauty came about..
The following words by Alan Hawkes.
I bought a G-boxx over a year ago after enquiring via Karl Heinz at Nicolai, so that was the starting point, after I'd decided on titanium the next problem was where to get the material as it can be quite hard to get the sizes you need hence some compromises.
I work in motor sport engineering, so I was lucky enough to get a piece of 60mm dia. ti tube for the down tube, which I then ovalised. The head tube is made in three parts, two rings for the headset to sit in and the center part is made from rolling up a piece of 3mm sheet ti, this was then assembled, welded, then final machined. The mounting for the gearbox is again made from 3mm sheet, folded carefully on a fly press just using eye to fit the contour of the gearbox, not easy!!
The most time consuming part was the swing arm pivots, machined from billet titanium, probably a good days work there! No CNC machines for me unfortunately. Even the seat tube had to be machined from a solid bar, if you were to make a few you could justify getting parts machined or water jet cut but for a one off it's not really viable.
The two top tubes are 19mm dia. and I even had to make a tube bender so I could get the desired angles. The actual assembly and building was not too difficult but then is my trade. The rear dropouts are fabricated from 3mm sheet with sliding alloy parts for the axle to go through.
I drew up the suspension layout on a board and made various pieces of metal until I got the desired amount of rear wheel travel for the shock length and to get a rising rate, then once that was done I could machine these parts from alloy, these are not yet really finished but I wanted to make sure everything works OK before I spend hours machining something just to make it look prettier!
So once I had all the parts all I had to do was put it all together, simple really. I made an 'L' shape jig into which I clamped both wheels at the intended wheelbase, then fitted the forks and head tube, set these at the correct angle, fitted the gearbox onto a mounting plate on the jig, then basically measured, cut, ground and offered up the down tube until it fit perfectly! Then I did the same with the rear end, then made a separate jig so I could weld the swing arm without distortion.
Refitted the swing arm then attached all the suspension parts, then made another fixture to hold the seat in the correct place and cut and bent the tube to fit between the seat tube and head tube. Then just a case of welding it all up and off for test rides.
The first proper ride I had on the bike was at the first round of the Caersws Cup 2009 so a baptism of fire really! Only a couple of minor issues with the chain really but these were soon sorted.
So that is how you build a titanium gearbox bike, I'm never satisfied so I have already started building another bike, this one is going to be more conventional though, made from t45 again and seven inch travel with single crown forks, hoping to get a lightweight downhill/freeride bike, hopefully by July, so I have a lot to do.
Alan Hawkes
Alan, many thanks for your detailed words and inspiration to all Meccano players out there.
Stay Unclipped!
Si Paton.
Descent-Gear.com
Troy Lee Sprint Shorts 59.99GBP Posted
84 Comments
- + 47
bender
(Jun 1, 2009 at 0:16)
Mr. Hawkes has some serious skills! Props on such an amazing homemade beauty
liking the two top tubes UNIQUE! i never new a home grown could look so nice, bet it is an awesome ride.
That is just amazing craftsmanship and engineering! I think it would look much better painted though.
No way, it's way better without as it's easier to see the pure craftsmanship gone in to create this beauty.
I do completely agree with that comment, but I also think it looks kind of unfinished without paint. That's obviously personal preferance though, as I know some people raw their own frames because they like it.
i agree with Spike X, there is alot of welding on that, which means alot of metal discoloration, i nice color of paint would make it much better looking.
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impressive frame work! I'd love to get the skills and the material. Just please, this fork is a disgrace for this bike... hello Marzocchi! its 2009, ppl weld Ti frames by themsleves and u still put >3,5kg fork on the market!
id expect it to be around that, possibly with the shock, the diamondback sabbath with shock gearbox and paint is 22lb and thats a semiu steel construction i think
Very impressive! Looks clean especially for a gearbox bike, which somehow often tend to look massive (from several manufacturers).
Hmm, motor sport engineering, more "conventional" t45 (conventional in the UK) and into assembling all kind of metal tubes... Sounds like normally more into roll cages / tubular chassis.
Hmm, motor sport engineering, more "conventional" t45 (conventional in the UK) and into assembling all kind of metal tubes... Sounds like normally more into roll cages / tubular chassis.
That is awsome!! This bike is very impressive!!
I have to get startet in building my own DH bike. I have tought alot about building a ti DH bike. But the material is very expensive...
You know what it weighs?
I have to get startet in building my own DH bike. I have tought alot about building a ti DH bike. But the material is very expensive...
You know what it weighs?
That's a major Beauty! I bet that's mad light weight! Such sick skills! You should start your own bike frame brand! 
Im a welder by trade, and have wanted to build my own frames for ages.
Ive never welded Ti, but id give it a go.
You live about 5min from my mum and dad. (providing that you live in Banbury, like the photo sujests).
How much did it cost to make that frame? and I cant find a G-Boxx anywhere for sale!
Ive got a good metal supplyer, but havent got any room for jigs atm (want to knock out some lightweight DH/Freeride bikes as a hobby).
How much does that bike weigh?
Dave
Ive never welded Ti, but id give it a go.
You live about 5min from my mum and dad. (providing that you live in Banbury, like the photo sujests).
How much did it cost to make that frame? and I cant find a G-Boxx anywhere for sale!
Ive got a good metal supplyer, but havent got any room for jigs atm (want to knock out some lightweight DH/Freeride bikes as a hobby).
How much does that bike weigh?
Dave
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I give tons of credit for designing and fabricating that bike. Most people have absolutely no idea how difficult it is to take on a project like this and see it through successfully. Props.
But...those welds are contaminated, embrittled and the frame is going to break. Welded titanium should show no color at all or at most a light straw brownish color if it was kept sufficiently clean and this bike doesn't appear to have been cleaned properly nor has it been welded properly. I wonder if the frame was purged during welding? I sincerely hope that the first failure is a minor one.
FWIW - I make my living welding and fabricating titanium.
But...those welds are contaminated, embrittled and the frame is going to break. Welded titanium should show no color at all or at most a light straw brownish color if it was kept sufficiently clean and this bike doesn't appear to have been cleaned properly nor has it been welded properly. I wonder if the frame was purged during welding? I sincerely hope that the first failure is a minor one.
FWIW - I make my living welding and fabricating titanium.
Just what i was going to say, serious weld oxidisation evident on this frame - Titanium frames must be welded in an O2-free atmosphere to ensure maximum weld strength/durability, otherwise they absolutely will break (ask anyone who owned a Clark Kent frame back in the 1990s) The rainbow discoloration is a tell-tale sign. There is a reason good Ti frames cost so much - production is very time-consuming and expensive. I'll second what Vertigoat said - hope the first crack isn't your headtube snapping off. That aside, this is a very impressive homemade bike, hopefully you'll find a way to make Mk.2 a little more durable.
As a welder with some ti experience I unfortunately have to agree with the above two posters. Back purging the frame would eliminate much of this. Still very very impressed with your fabrication skills, and the appearance of the welds, minus the discoloration, looks pretty damn good.
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not a critisism but it looks very similar to the ancilotti pullshock dh bikes (apart from the gearbox obviously) but those are such sweet looking bikes its actually a compliment now i think about it. but yeah good job how much did it cost to make coz ti billet and tubes are f*cking expensive if bought in small amounts
how much do u think itd run me to make a bmx bike thats styled like the black eye killarodo???....dont u have to weld ti in an aragon chamber? or it is crappy
to peddlepusher15
You don't have to weld ti frames in an argon chamber, but the inside of the frames must be purged with Argon and all other air must be expelled before weldling. Most people in the bike industry use purged heatsinks, baffles, dams and foil to protect the weld zone from absorbing oxygen. It's also necessary to use a much larger gas lens and nozzle that bathes the top surface with argon. You can't weld more than about 1/2" of joint with a standard cup&nozzle without getting contamination.
You don't have to weld ti frames in an argon chamber, but the inside of the frames must be purged with Argon and all other air must be expelled before weldling. Most people in the bike industry use purged heatsinks, baffles, dams and foil to protect the weld zone from absorbing oxygen. It's also necessary to use a much larger gas lens and nozzle that bathes the top surface with argon. You can't weld more than about 1/2" of joint with a standard cup&nozzle without getting contamination.
firstly to all the ti welders/fabricators thanks for the advice, its all been taken on board, the welds were purged although not welded in an argon chamber, i make exhausts for motorsport and thus far we have had no problems with breakage, i guess it also depends on your industry, i.e aviation,powerstations etc. i do always check for cracking etc as well so we'll just see how she goes, it was only an experiment. the head angle is 65deg and she weighs 45 pounds, same as the nicolai. my next bike that is currently in build is back to my favoured material t45, a bit easier to work with but still can be a beatch to bend! so hopefully when its done the guys at pinkbike will be kind enough to put that one on here as well. cheers guys al
It really is a great effort and my intention wasn't to undermine the accomplishment in any way. I know how much of an undertaking it is to build fixtures to support a specific project. The amount of time and planning isn't to be overlooked. Great work!
congrat's albert666. interesting build thats got alot of people on here talking. either way mate, your pushing the envelop on the development side of life be it only one bike on your own workshop. If you could somehow come up with a new suss' design then you'd have people biting your arm off if its a good one.....
cheers for all the comments, there seems to be a lot more good vibes going on here than some other uk based sites : )
i have been trying to build a suspension design based around the honda unit pro link or the ktm rc8 design, but other mtb companies are doing as well so i'm just keeping a relatively simple design on my next project, after all look at the time that separate the world cup riders and they are all on various suspension designs, so whats best? all i'd say is don't believe the hype, simple is often the best, just get a good shock set up and ride hard!!
i have been trying to build a suspension design based around the honda unit pro link or the ktm rc8 design, but other mtb companies are doing as well so i'm just keeping a relatively simple design on my next project, after all look at the time that separate the world cup riders and they are all on various suspension designs, so whats best? all i'd say is don't believe the hype, simple is often the best, just get a good shock set up and ride hard!!
seconded. its not the rig that wins the races, its the rider making it work with whatever he/she has under their feet and hands.
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well i bet its a dam sight stronger that your "americlish"???!!!! hahahaha sorry dude, couldn't resist.
im thinkin about makin a bike next year . i already made one like 2 years ago but i wasnt satisfied.
one of the coolest things I have seen on PB.
Nice indeed.
Looks like it's largely based off of an RMX? From what I've seen, it's a worthy design.
Nice indeed.
Looks like it's largely based off of an RMX? From what I've seen, it's a worthy design.
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Mad props...that is completely ill...I tried welding once...only one person ended up in the hospital.
the measuring and the cutting all look good and i really like the idea of Ti. but I'm not to shore about those welds.
I have done plenty Ti welding my self to know that that the welds do not look right (even through the pic)
some of the welds haven't forged enough to have the strength to hold a heavy rider and the coloration in the metal, if the weld was done correctly, there should not be any blue heat markings, when the coloring is there it means that the Ti is now contaminated and is much more at risk of cracking.
the crakes wont show up for a while but i would recommend keeping a very close eye one those welds( especially at the head tube.
I have done plenty Ti welding my self to know that that the welds do not look right (even through the pic)
some of the welds haven't forged enough to have the strength to hold a heavy rider and the coloration in the metal, if the weld was done correctly, there should not be any blue heat markings, when the coloring is there it means that the Ti is now contaminated and is much more at risk of cracking.
the crakes wont show up for a while but i would recommend keeping a very close eye one those welds( especially at the head tube.
agreed...fantastic effort but far too much heat applied. the welds will be extremely britle, but they may be strong enough just by the size of them and the gussets. i guess we'll find out in time??
Hi,
I seen your frame with G-Boxx. Congratulation!!
Have you build now your new frame? My dream is build a bike in titanium like you with g-boxx and this year I would like design for next year build the frame. One question more. When you buy the G-boxx? Have you a contact or email? How much? Thanks,
Best regards,
Pedro Jerónimo from Canary Islands.
See this freeride videos from Canary Islands,
RUTA VALLE SECO
http://www.vimeo.com/6616260
RUTA PUNTA HIDALGO
http://www.vimeo.com/6613901
I seen your frame with G-Boxx. Congratulation!!
Have you build now your new frame? My dream is build a bike in titanium like you with g-boxx and this year I would like design for next year build the frame. One question more. When you buy the G-boxx? Have you a contact or email? How much? Thanks,
Best regards,
Pedro Jerónimo from Canary Islands.
See this freeride videos from Canary Islands,
RUTA VALLE SECO
http://www.vimeo.com/6616260
RUTA PUNTA HIDALGO
http://www.vimeo.com/6613901
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