While the bike in the first post looks great and is an inspiration in terms of weight anyone interested in a build like this before getting too excited should think of three areas related to it: Cost, quality and weight.
Cost
Raxel, the creator of said bike, said the bike
had costed him 3600$ (I think on another occasion he later stated 4000$ but ATM I cannot find it). He sourced most of the parts from all over Asia, mostly China. And he seems to
have paid considerably less for the frame and the stem than the sellers on
ebay charge. From above linked post:
I have paid $1200 for titanium frame + handlepost (combo deal), $300 for fork and $480 for rear frame. Ultralight wheelset was $190 (Chinese magic!)
If you are in Europe, shipping import VAT and customs will add to the price. Customs for bike parts are 4,5%, import VAT depends from the country you are in but is around ~20% most of the time (identical to your local VAT). So you can add around 25% on top of the outlined price if you are in Europe. If you buy a complete bike instead of parts customs are 14% (instead of 4,5% for parts) and if you buy a complete bike from China an anti-dumping tax of another 45% may apply, according to European law. This way a bike built from imported parts will cost you not the 3600-4000$ Raxel paid but rather 4500-5000$ - if you manage to get the same prices he did and do not have to pay additional shipping charge. Else you'll pay more. You'll end up even more expensive if you import a complete bike. And if the customs officer in charge is knowledgable, curious and picky he may consider the frame a copyright infringement and you may with some bad luck end up with no frame but an emptied bank account - cannot judge on the risk of this happening. But as 2004 and 2010 Brompton clones
were impounded for exactly that reason and since then as to my knowledge no clones are officially offered in Europe this seems at least possible.
Weight
The weight of the bike in question is totally impressive at it's 5,9kg. But when looking a bit closer you'll notice, that
"only" about 1,1kg of weight loss are due to the ti-frame and ti-stem instead of the Brompton steel one (the ti-frame Raxel used saves ~730g on the main frame and ~390g on the S-stem compared to the steel pendants from Brompton). A stock Brompton S2Lx is quoted at ~9,7 kg, so a whopping 2,7kg are saved elsewhere, not on frame an stem (9,7kg - 5,9kg - 1,1kg). Which you could obviously do with a "real" ti-Brompton as a basis, too. Light builds on the basis of a stock ti-Brompton have come as low as 6kg in the past w/o the use of additional ti-frame parts or carbon magic.
The first 1 - 1,5 kg are can be achieved relatively easy, quick and reasonably cheap by using ti-bolts, a ti- or carbon-seat post, a lighter chain, a lighter crank set, a lighter saddle and stuff like that. It is typically not the big win on a single component but the sum of small wins on many components that do the trick. Currently a single speed full steel Brompton is for sale on ebay.uk with a
claimed weight of 8,8kg - w/o a titanium frame and w/o and w/o any ti-bits. A stock steel S1E Brompton is rated at 10,4 kg in the Brompton bike builder, so this guy saved 1,6kg on his bike.
A lot of additional potential is in the wheel set (though not necessarily very cheap) and a quick win is in the tires - i.e. Kojaks, namely the folding one, save a fortune in comparison to i.e. Marathons let alone M+. But there comes the factor of practicability into play: If you need blades due to the weather you have to live with the weight. If you want light tires, you have to live with a puncture from time to time. If you want a very light wheel set you'll end up with a limited choice of tires and none of them is very puncture resistant. If you want a carrier block you have to live with it's weight and if you need lights to ride in the dark they with weight something. So low weight sometimes comes at a price beyond from money that you are willing to pay or not. A lighter Brompton is worth not too much if it is not fit for the purpose you plan to use it for... I.e. you can save noticable weight by getting rid of the folding pedal and exchanging both pedals for i.e. eggbeaters. But is that what you want for your everyday commute and usage? So don't get blended by the weight alone but check what side effects are tied to it. It is easy to create a light showroom bike, it is harder to create a light bike that is actually comfortably usable in daily life w/o compromise - and the latter will probably weight more. I think raxel pointed out at some point that his 5,8 kg build (that was a gift to his wife) ended up noticably heavier in daily usage (but can again not find the according post).
Quality
Brompton have been building their frames and bikes for many years now and each and every year found something to be enhanced - there has been a massive amount of incremental improvements over the last 30 years and possibly more to come. The bikes are certified to European safety norms (as any bike has that is sold in Europe). The clone frames are not. They have just hit the marked, they are not certified in any way and it is questionable if they are tested in terms of safety and endurance. They have the shape of a Brompton frame but that does not at all mean they would have the same quality and meet the same safety standards. But obviously it does not automatically mean they would be unsafe or unreliable - it just has not be tested and thus is an (expensive) bet that you may be willing to take or not. And in the worst case it may end up being a bet with your health or even your life. And this does not only affect the ti-frame but obviously also the components. A lot of the tuning parts for the Brompton come from Asia and were designed and build with the local market and an Asian rider in mind that is typically on average smaller and lighter than it's European or American counterpart. And it may even be designed to just be light but not able to withstand daily use or it may even be build with no knowledge of construction, just to look like the original and to be to produced as cheaply as possible. I.e. a cheap and light wheel set from China (Raxel used a Chinese wheel set costing 190$ in his build) that is strong enough for a 60 kg person, slowly and sorrowfully blinging around with his show bike in South Korea might not be able do deal with the demands of a 90kg British rider, pushing the bike harshly over cobblestones and curbs everyday during his commute for years and years. Or it may be - the problem is: You do not know it. You simply have no knowledge who is actually building these parts, how qualified they are, what level of experience they have, what sense of quality, of which quality the materials and parts have that they are using, what the specifications are (and on which foundation), wether they have any quality control or not and what the criteria of that quality control may be if one exists. Sounds like a serious bit of gambling to me. Being thousands of kms away from the makers and neither understanding the language nor the local culture does not help either.
But we have not to go that far - quality issues start earlier. In the
thread on bike forums about the build another owner of a full-ti-clone frame popped up and recommended (starting with post #40 in the thread):
However, I don't recommend people to buy one. (...) The biggest problem with those 3rd party main frame is you might experience some compatibility issue when building your bike. Some of them are easy to be fixed but some of them are not. If you really want to buy one, just remember to build the bike as soon as you get it. If you find any problem, just return it. Buy from ebay, not Alibaba so if there is any problem, eBay can still protect you and help you to get your money back. (...)
3/5 of the people I know who purchased the titanium main frame they returned. I know the sample size is very small but still I think that's a very high ratio. Anyway, like I said, you can definitely build one if you want. Just make sure you buy from the right place. I purchased the main frame, rear frame, fork, and stem all together. When I found out I had issues with the fork, and rear frame and tried to replace with Brompton OEM parts, they just didn't work. So right now, I can't fold properly if the chainring I use is bigger than 52T.
I have probably one of the best mechanic in Taiwan built the bike for me. It is just the product issue, not whom built the bike. That's my 2 cents.
Raxel, the creator of the 5,8kg Brompton, who strangely enough seems to hate Brompton from the deep of his soul and considers everything coming from them to be ridiculously overpriced and at the same time of crappy quality (
"And honestly all the stock Brompton parts are quite crappy and has negligible resale value anyway nowadays (at least here... many people just use the frameset and dump the rest)") but is in massive favor of Asian created clones answered:
My frame has very slightly oval headtube and the BB shell threads were bit too tight (couldn't hand tighten the bottom bracket). Using tools solved both issues just fine.(#41)
(...) Mine was VERY slight oval, and headset press worked just fine. Worse frames may need reaming and facing.(#49)
So overall I'd take the news of this build with a big grain of salt. While it is no doubt impressive on a second look it seems less attractive, at least to me: A frameset of unknown origin, specification and quality with a high failure rate and despite a high price tag a high failure rate, low compatibility and the need for massive rework to an amount that would be unacceptable to me. A weight saving through that frame that is less impressive than one would think. A build that needs massive compromises close to or over the limit to make it a bike for daily usage. An unclear lifespan and an unclear (but probably dissatifactoring) warranty and after-sales service. A lot of Asian parts of unknown quality and origin. All that at a very high price plus the risk that the whole thing gets impounded at customs. I think I pass...
Complete Ti-Clone-Bromptons
In the meantime there are fully built ti-Brompton-clones from China for sale on ebay like this
https://www.ebay.ca/itm/EasyTi-Titanium-Brompton-Folding-Bike/223483789507 for 2980$ or that
https://www.ebay.ca/itm/Titanium-Br...eed-with-Mudguards-and-rear-rack/132924637709 for 2880$ - they look essentially like the same bike, though formally claimend from different makers. Sold as "Titanium Brompton folding bike" and "EasyTi Titanium Brompton Folding Bike", shamelessly misusing Brompton's brand. If you look at the bike...
... you'll recognize that it seems a bit of a strange set. Some parts like the rear frame clip, the saddle or the pentaclip seem to be genuine Brompton parts or identically looking imitations. But you'll also notice things like the cheapest folding pedals on the market, uncut brake cables, a far too long fender on the rear, a lacking mudflap on the front fender, cheap brake levers etc.. All that on a bike for 3000$. Plus 14% customs plus 20% import VAT which bring you to a real consumer end price of ~4200$ including shipping if you are from Europe. Without considering the potential 45% anti-dumping tariff for bikes from China on top and the risk of getting the bike impounded at customs. With a declared weight of the bike of 10,3kg - which is possibly partly caused by a (too) short seat post and the usage of a (heavy) 3-speed hub - a bit of a strange combination on a full titanium frame. For a 3-speed Brompton clone, where a comparable full steel M3L weights 11,5kg (according to Brompton's bike builder) and costs 1010 Pounds list price. A very epensively saved 1,2 kg if you ask me. This may give you an impression of the understanding, attitude and sense of quality of the makers and sellers of these clones...
Those
easy-Ti guys are apart from the complete bike also selling a
ti-Brompton main frame for 900$ plus shipping and rated at 1,7kg (a steel Brompton main frame weights ~2,1kg, so the declared effective weight saving is just 400g, Raxel claims his ti-frame
would weight 1271g and he had seen frames as low as 1100g) and a
ti-S-stem which they say is "Ultra lightweight" but do not bother to outline what weight it actually has...
In the end: fascinating build by Raxel, reality check shows: not for me.