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Custom lots-of-titanium Brompton
 
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Old 4th January 2013   #1
danstuffdonor
 
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Custom lots-of-titanium Brompton

OK, so it's a Brompton, and therefore deeply uncool, but bear with me...

While riding to the train station the other day, I had something of an epiphany - I realised that (1) I ride my Brompton more often than any of my other bikes (not in terms of mileage, obviously) and (2) it was shagged. Obviously the sensible option would be to rebuild it. Rather than doing that, I've decided to build a new one. And to make it a bit special.

Starting point - a new clear matt laquer frame:



But I wanted a titanium seatpost, and Brompton no longer make one. Happily, a nice Dutch chap living in Thailand trading under the name Brompfication does make one. And rather nice it is too, along with the other bits he makes. All the components on the seatpost are titanium, even the clamps and bolts:



The saddle's a Charge Knife - like a cut-down Spoon but with titanium rails, sticking to the must-have-titanium theme. Seeing as it's a long way from Thailand, it seemed worth buying a few more bits of Brompfication Bling from him, such as the bronze release clamps:



(which are rather nicer than the Brompton ones since they're cunningly designed so that the V-clamps stay in the right position rather than spinning around in an annoying fashion) together with the aluminium roller wheels and the titanium rear frame clip kit:



Added to this so far is a titanium rear frame and some Campag carbon Record cranks (fitted with a Centaur 115mm sealed bottom bracket). It's early days, but after waving a tape measure over the cranks, I think it'll work. I'll only have the 53t chainring, which I'm planning to swap to the inside of the crank spider.



Next step, some wheels...
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Old 4th January 2013   #2
skivedonor
 
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liking the glass of wine.
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Old 4th January 2013   #3
jb000donor
 
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This is exciting me
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Old 4th January 2013   #4
loctezdonor
 
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This is looking very interesting, what are you going to do about forks/bars? Can you get them in titanium too? I am beginning to wish I still had my brompton.
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Old 4th January 2013   #5
danstuffdonor
 
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Quote:
Originally Posted by loctez View Post
This is looking very interesting, what are you going to do about forks/bars? Can you get them in titanium too? I am beginning to wish I still had my brompton.
Yep, front forks will be the titanium ones, the handlebars will be some flat 25.4mm straight bars I got from Taiwan via eBay. Can't fit either yet as I haven't got the stem or the headset yet.
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Old 4th January 2013   #6
finger_jockeydonor
 
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This might be good reference if you're planning on going fixed


http://www.flickr.com/photos/littlepixel/2173983253/
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Old 4th January 2013   #7
cornelius blackfoot
 
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When I was in Thailand, met the Bromptification guy at a restaurant by the train station, cool guy
#csb
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Old 4th January 2013   #8
ncjlee
 
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Or like this?

http://www.lfgss.com/thread27801.html
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Old 4th January 2013   #9
rodabod
 
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I'm sitting next to my colleague's titanium Brompton.

He fancies a re-spray. Is the original spray powder coat? I assume these bikes must be prone to chipping.
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Old 4th January 2013   #10
hugo7donor
 
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^ the paint on bromptons is very tough - I've always assumed PC.


From my searching the Brompton ti forks are around £270.

For that money would it be worth having some custom light weight steel ones built? There may even be enough spare to work out a cleaner a-head alternative to the bulky stem fold section.


Oh and these look great. My dad's ones are quite wide (stake wheels I think) and sometime catch on my trousers.

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Old 4th January 2013   #11
tiloverdonor
 
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i have a brompton with ti bits too - for bars you may as well go carbon but if i were buying the forks for it i'd probably just go steel too - you could get some sexy custom ones made for less than the price of ti and you can sort it to run better callipers more easily ( i run campagnolo TT ones but they required a dremel and some patience)

http://www.flickr.com/photos/tomcutting/7888900910/
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Old 4th January 2013   #12
hugo7donor
 
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What wheels/rims are you going to use?
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Old 4th January 2013   #13
danstuffdonor
 
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OK, time to 'fess up, it's not going to be fixed - I've got a 5 speed SA hub for it. Even applying Rule No. 5 as much as I can, I need some gears for the routes this'll be doing (like South End Green to Whitestone Pond).

I hadn't thought about getting some custom forks made up. Not a bad idea at all, but I've already got the ti forks, so I think I might as well use them. Personally I've never had any issues with the Brompton brakes. They're not brilliant by any means, but given a good hearty tug I can lock up either wheel if I want to.

My understanding is that Brompton frames are all powder-coated except for the clear laquer finishes which, as the name suggests, is a wet paint.

As for wheels and tyres, all will become clear! Working on the front at the moment, rear will follow shortly. However, I need to make some mods to my wheel-truing stand before it can take weeny 349 wheels.
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Old 5th January 2013   #14
nodachi1
 
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This is brilliant. I love Bromptons and think they are cool no matter what anyone else says. Shouldn't you be worried about overtorquing carbon bars, as the handlebar bolt design looks rather old school?

Also, what stem are you going to use - M, S, P or H?
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Old 5th January 2013   #15
danstuffdonor
 
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Quote:
Originally Posted by nodachi1 View Post
This is brilliant. I love Bromptons and think they are cool no matter what anyone else says. Shouldn't you be worried about overtorquing carbon bars, as the handlebar bolt design looks rather old school?

Also, what stem are you going to use - M, S, P or H?
Shouldn't be an issue, as the bars are titanium too. They're flat bars, so I'm going to be using an S stem. I'm currently waiting for the stem (2 week order time) but the main problem at the moment is trying to source a Chris King Gripnut headset. It looks like I'll have to order to headset specially, which leaves one burning dilemma - pewter or gold for the headset?
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Old 5th January 2013   #16
hippy
 
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Has there been a mostly cabron Brompton? If not, why not? Steal the design, lay it up yourself at home (not a euph). No? Okay nevermind.
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Old 5th January 2013   #17
the-smiling-buddha
 
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Quote:
Originally Posted by danstuff View Post
OK, time to 'fess up, it's not going to be fixed - I've got a 5 speed SA hub for it. Even applying Rule No. 5 as much as I can, I need some gears for the routes this'll be doing (like South End Green to Whitestone Pond).
I just built an Airnimal with a fixed wheel, but when I was having the wheels built I had an extra one built with a 5 speed SA hub for touring, so it will be interesting to compare the Brompton to the Airnimal. Mine rides SWEET as a fixed.
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Old 5th January 2013   #18
jb000donor
 
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what bars are you using?

*ignore me. Ive just read it

Last edited by jb000; 5th January 2013 at 12:56. Reason: re-read thread
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Old 5th January 2013   #19
mdcc_testerdonor
 
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Quote:
Originally Posted by danstuff View Post
It's early days, but after waving a tape measure over the cranks, I think it'll work. I'll only have the 53t chainring, which I'm planning to swap to the inside of the crank spider
That's not as simple as it sounds, the Campag carbon cranks use non-standard chainring bolts and you'll need to make a spacer to replace the outer ring where it's sandwiched between the inner and the back of the crank, and if I were you I'd make some washers to spread the load of the chainring bolts on the outside of the spider arms too. Aesthetically, it would be better to use a shorter BB and leave the rings where they are, just cut off the teeth and ring part of the inner and leave the tabs to do all your spacing and load spreading duties. Somebody on here did exactly that for a UltraTorque Pista conversion on some carbon cranks recently.

Also, the outer ring is ramped, pinned and has lowered teeth, so expect frequent chain drop. For all of the above reasons, I can't help thinking that Record is not the way forward, and a 130mm pcd crank with 5 arms will provide more options, including this commuter friendly 57t chain ring with integral guard.

Last edited by mdcc_tester; 5th January 2013 at 19:32. Reason: oh, ah.
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Old 5th January 2013   #20
CHUG_IT
 
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I'm tripping balls on the final cost of this setup. I like it though.
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Old 5th January 2013   #21
loctezdonor
 
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Quote:
Originally Posted by mdcc_tester View Post
Also, the outer ring is ramped, pinned and has lowered teeth, so expect frequent chain drop.
Surly if he's going to be using a hub gear the chain line won't be changing? But I agree, although very cool, these cranks could creat some issues like chainring bolt lengths.
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Old 5th January 2013   #22
mdcc_testerdonor
 
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Quote:
Originally Posted by loctez View Post
Surly if he's going to be using a hub gear the chain line won't be changing?
No, but the chain still flaps about, and it's going to need a sprung tensioner to accommodate the variation in chainstay length when folding, which will probably make matters worse. There is an increasing number of chain guides on the market serving the 1×n MTB and CX crowd, so it's not the end of the world.
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Old 5th January 2013   #23
Skully
 
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5 speed? Two speed deraillieur ftw. Though I recall bmmf saying the mech is rubbish...
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Old 6th January 2013   #24
danstuffdonor
 
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A two-speed derailleur set-up might win me points for style, but it won't help get me up to Whitestone Pond - not with gearing that'll help me crack the 40mph barrier (I've wound the current Brompton up to 37mph with the assistance of gravity, so 40mph is the next step).

I'll be using a chain tensioner, the standard Brompton one. As mdcc_tester has correctly identified, the effective chainstay length on the Brompton changes when you fold the rear wheel under, so some sort of tensioner is necessary.

As for the chainrings/cranks, the plan at the moment is to dig out a suitably-sized sheet of titanium from my stores, give it to a nice man with a water cutter, and have a titanium chain guard made up and fit that in the outer ring position. I can't see that the ramps and pins will have any effect, but if the lowered teeth are a problem (and at present I suspect they won't be) then a combination of another sheet of titanium, said nice man, and my CAD package (which has a function for plotting chainring teeth) will result in a new titanium chainring with full-height teeth. All other issues should be capable of being overcome with time, and the assistance of my milling machine and lathe...
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Old 6th January 2013   #25
nodachi1
 
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Why no carbon brommie?

Quote:
Originally Posted by hippy View Post
Has there been a mostly cabron Brompton? If not, why not? Steal the design, lay it up yourself at home (not a euph). No? Okay nevermind.
I asked them that very question on the factory tour, and they said they don't have time/resources to devote to a full carbon Brompton. Basically, they can't be arsed.
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Old 6th January 2013   #26
danstuffdonor
 
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I can understand why. Making something from carbon is fundamentally different from making it from steel or even ali given the nature of the material. If you just copy the design but make it from carbon instead then it's very unlikely to work well. I've done a fair bit of work with carbon myself, both wet lay-up and pre-preg (vacuum-bagged in a home-made curing oven) and the only way of making a Brompton-esque frame from carbon would involve high pressure moulds. That would require either an autoclave or inflatable internal bladders, and even a simple mould (machined from a large block of aluminium billet) would cost tens of thousands to produce. Making the fixtures like the frame clamps and pivots together with the pivot tube for the rear triangle would be a total nightmare in carbon.

In some ways carbon would be an ideal material for a Brompton - the stiffness would be useful given that it's essentially a single beam frame. But in lots of other respects it'd be a disaster, I suspect.
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Old 6th January 2013   #27
hippy
 
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I reckon it'd be great but they know what they're doing with tubing and the costs sound prohibitive if they can't make it work so I can understand their reaction to the question.
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Old 6th January 2013   #28
mechanical_vandal
 
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Quote:
Originally Posted by danstuff View Post
I can't see that the ramps and pins will have any effect, but if the lowered teeth are a problem (and at present I suspect they won't be)
I'll never ride s/s with a geared ring again.

There's a transit van driver somewhere in Glasgow that'll be able to explain why.
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Old 6th January 2013   #29
mdcc_testerdonor
 
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Quote:
Originally Posted by mechanical_vandal View Post
I'll never ride s/s with a geared ring again.
Same here. The gravel rash healed, but the bib-tights I wrecked cost more than a good SS chainring.
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Old 6th January 2013   #30
the-smiling-buddha
 
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Chain break?
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Old 6th January 2013   #31
mdcc_testerdonor
 
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No, just jumped off as I was caning it up a small slope.
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Old 6th January 2013   #32
Skully
 
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Oscc
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Old 6th January 2013   #33
mechanical_vandal
 
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It was a jacket, front light, front rack, 2 brake levers and a saddle for me.

And almost my life.

All items that individually cost more than a basic ss ring and together, a lot more than a good one.
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Old 6th January 2013   #34
Skully
 
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@ OP So ... let me get this straight ... you need lots of gears to achieve +37mph on a Brompton up a slope that's a pond? Weird.

I'd build your own plastic one, go on, it's there for the taking.
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Old 6th January 2013   #35
luckyskulldonor
 
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i like this project. really looking forward to seeing how it turns out. put a smile on my face.
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Old 6th January 2013   #36
danstuffdonor
 
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Quote:
Originally Posted by mechanical_vandal View Post
It was a jacket, front light, front rack, 2 brake levers and a saddle for me.

And almost my life.

All items that individually cost more than a basic ss ring and together, a lot more than a good one.
Odd, because my SS MTB uses the standard geared middle ring, and I've never had any problems with the chain dismounting. Mind you, my track bike and fixed-gear bikes both have SS chainrings, so to err on the side of caution, a 52t Miche 135BCD chainring is winging its way to me. Means I'll have to use a 1/8" chain rather than the 3/32" one I had set aside, but that's no great hardship, although I suppose I may as well get a 1/8" sprocket for the SA 5-speed hub rather than the 3/32" one I've got at the moment.
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Old 6th January 2013   #37
mechanical_vandal
 
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I've used gear components to run ss in the past too without much hassle.

It only takes one instance of seeing a tranny can struggle to find the grip required to stop before squashing your head to convince you it's a ss chainring is a worthwhile investment though.
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Old 7th January 2013   #38
mdcc_testerdonor
 
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Not that proper equipment makes you completely immune to chain drop. I had the chain off my TT bike once on a bumpy downhill section, and to head off the OSCC, I had to undo the track nuts to get it back on so there was nowt wrong with my chain tension.
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Old 9th January 2013   #39
Littlepixel
Heh. That's my one! Better more recent pic of it here with racing wheelchair tyres and Aerohead rims:
http://farm4.staticflickr.com/3022/3...2ccc20aa_b.jpg

[Thanks for the props!]

http://www.flickr.com/photos/littlep...57615886030030
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Old 9th January 2013   #40
finger_jockeydonor
 
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That is such a sick set-up. Love it.
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Old 9th January 2013   #41
the-smiling-buddha
 
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I'd like to race that
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Old 9th January 2013   #42
cleftydonor
 
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Quote:
Originally Posted by hugo7 View Post
^


Oh and these look great. My dad's ones are quite wide (stake wheels I think) and sometime catch on my trousers.

I bought some of those luggage wheels a couple of years ago, unfortunately whilst they look lovely I found they were very unstable and the rubbers came off within a couple of weeks.
If only they were a little thicker they would have been great.
I bought some of these in the end and they have been great, very stable and hardwaring.

Rest of the build looks great!
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Old 22nd January 2013   #43
danstuffdonor
 
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Making life unnecessarily complicated Pt 1 - QR seat clamp

The standard QR seat clamp on the Brompton, which came with the main frame, is good for two reasons. Firstly, it stays in place and doesn't spin round due to the fact that there's a slot in the steel seat clamp which forms part of the main frame and a matching ridge in the QR seat clamp. Secondly, it fits and is designed to work with the steel band brazed around the seat tube.

But it's a bit boring and fugly, so I decided I'd replace it with a Hope QR seat clamp. However, the Hope seat clamp doesn't have the ridge to keep it in position, and the shaft on the QR lever is too short. So the first thing to do was to disassemble it.



In order to keep the QR lever from spinning round when it's undone, I got a spare bit of brass tube out of the offcuts bin, machined a recess in one end on the lathe which the brass bush from the Hope QR lever fits into, and milled the locating ridge on the other end. This is part way through the machining process on the lathe:



I also needed to make a longer pin for the QR lever, with 5mm threads at both ends but a 6mm diameter in the middle (to match the rear triangle release catch), so I used a long stainless 6mm bolt and turned it down to suit. I also had to machine down the Hope aluminium nut. Reassembled, it looks like this.



And in place it looks like this:




Took hours to do, of course. And the Hope sign on the QR lever is still upside down...
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Old 22nd January 2013   #44
biv3
 
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nice seeing the process steps
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Old 22nd January 2013   #45
Object
 
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Looks good, I'd suggest possibly replacing the silver nut that came with the Hope QR as the aluminium is very soft and has a habit of stripping.

I like upside down logos (This is irrelevant but I thought I'd share).
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Old 22nd January 2013   #46
Dammitdonor
 
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I have lathe envy
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Old 22nd January 2013   #47
danstuffdonor
 
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If it does then I'll machine a new pin with an M6 thread on one end and M5 on the other and just use a standard M6 nyloc to replace the Hope ali nut. But it can stay for now, 'cos I think it's mighty purty...
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Old 22nd January 2013   #48
danstuffdonor
 
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Quote:
Originally Posted by Dammit View Post
I have lathe envy
It's in the dining room, along with the milling machine, pillar drill and TIG welder...
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Old 22nd January 2013   #49
drøndonor
 
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Quote:
Originally Posted by danstuff View Post
It's in the dining room, along with the milling machine, pillar drill and TIG welder...
wtf. pics pretty please. I'd love to live like that. I think.
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Old 22nd January 2013   #50
bodieanddoyle
 
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What an epic "man house".
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