mlau

I've been thinking a lot about Raxel's titanium build for his wife.

Since I'm not all that handy, I was thinking of buying one of those ebay prebuilt easyti- Brompton clones.

Any thoughts on those bikes?

GTA

Up to now, I have experienced several titanium Brompton clones but to be honest, none of them is satisfactory.
There are two main problems.
One is stiffness. As long as it is Titanium, the "clone" of the main frame is definitely softer than the original steel frame. This brings an annoying bouncy and flexible ride. Recently, some clone frames start to use thicker tube (2mm), but still not much is improved. I can leave with titanium clone front fork and rear triangle, but really don't recommend titanium main frame and stem tube. As I know, even the Brompton factory has tried to make a full titanium version of the classic frame, but they failed. I think stiffness could be one of the reasons. That's also why now the T-line has a significantly different main frame design,
The other is machining accuracy. When the clones make copy and paste, there are always too many mistakes and tolerances, which often take place at the rear triangle joint, seat post clamp, caliper mounting holes, and so on. Any of these small defects could bring you big disappointment.

So my suggestion is no. Please consider enlarging your budget and order the T-line.

mlau

Much appreciated, GTA!

The ti Brompton was just one option I'm considering. Others include a Bike Friday Pakit (belt drive，ultralight, with Brompton carrier machined in place), Gocycle (not sure about proprietary parts and batteries), the possible Origami Swift (if it happens), or a Term BYB (with Brompton block).

We'll see how it goes. My fiance feels my Brompton (with Brooks saddle) is most comfortable. However, I feel that it's really lossy and inefficient with the rear hub wheel.

Jipe

With the bikes on your current list, it seems that budget isn't an issue, so did you consider the Birdy with an H&H Brompton block adapter ?

tcs

As a mechanical device, the three-speed hub is arguably the most efficient multi-speed drivetrain.

https://www.ihpva.org/HParchive/PDF/hp52-2001.pdf

Schwinnsta

The attachment would not open in due security issues on that site. I doubt the validity of the statement. A derailleur will be more efficient than a three-speed if both are in good mechanical order. I would agree three-speeds are more efficient than other multi-hubs. I suppose you can argue anything.

tcs

Over the last couple of years, we've all gotten familiar with friends and people whose company we enjoy who reject the results of instrumented tests and well-reasoned arguments out of hand, so that's cool.

I referenced a test by Dr. Chet Kyle and Frank Berto (who you will remember wrote a technical column for Bicycling magazine for ~25 years and authored The Dancing Chain) on the efficiency of bicycle gear trains for the International Human Powered Vehicle Association newsletter. If anyone else is having the trouble Schwinnsta did pulling it up, Google International Human Power Vehicle Association, click on 'Archives' and then choose 'HP52'. The report begins on page 3.

One facet the test overlooked that would pertain to (most) folding bike riders is the lack of data on 11T, 10T and 9T derailleur gear cogs. As the efficiency of derailleur gear drivetrains begins to drop off ever more precipitously when using cogs smaller than 14/15T, this really handicaps derailleur gear drivetrains used on small wheel bikes.

mlau

Much appreciated. Maybe my hub isn't well maintained?

Schwinnsta

I googled and found it with your instructions. It appears that they changed the grease to light oil and the hubs did well. They mention that manufactures use grease because commuters forget do maintenance. I always liked the old Sturmeys with the oil port, though they did not use light oil and did leak a little.

Pinigis 

yes. It will happen. We should have the design completed in two weeks, prototypes by June.

linberl

I have a pakiT (which I love but unfortunately am going to have to sell to fund a recumbent trike due to some health problems) and I can tell you it rides wonderfully! The belt drive, which I don't have, is really nice if you use it to commute, although using wax on my chain achieved a very good effect. I think you really need to ride the ones you are considering - if you call BF they will set you up with someone near you who owns a pakiT in your general size. That's how I tested out mine before buying. Testing a brompton is easy as they're available many places.
Not sure where you'd try a gocycle, though. Brompton is not one size fits all, it's one size fits "most" - I wasn't one of the "most". For ride quality, I'd suggest either the pakiT or the Origami Swift/original Swift. Fold=brompton/birdy.

Jipe

I don't agree with this latest statement: yes, for the fold, Brompton and Birdy are close (Brompton is still smaller) but on ride quality, the Birdy is much better than the Brompton and as good as a fast folding bike with the advantage to allow light gravel ride when equipped with 50mm wide tires.

Schwinnsta

Based on my experiences with Moulton, I tend to think I would not agree with you on Birdy. I would love to test ride a Birdy, BAFAIK, there are no dealers in North America. This is a big problem for the Birdy.

My guess, at best, the Birdy can be is 10% faster than a Brompton and for practicality it would be hard to beat a Brompton. It folds small enough to put in a suitcase without disassembly. It folds into shopping cart mode and be taken into stores. I don't have to leave an expensive bike locked outside supermarket. I stopped riding full size bikes, because the Brompton, while slower, was so much more practical.

linberl

I wasn't comparing the ride of the birdy to the brompton, I was comparing the fold. Imo the BF and Swift do ride better than the birdy. You can put wide tires on a BF and it's fantastic for gravel.

Jipe

I do not agree with you, the Birdy with derailleur or Rohloff (not the poor Nexus 8 version) is as fast as the fastest 20" folder if you mount the same fast tire on it. If you look at being fast, the most important part is the tires.

And the Birdy can be a 20" folder because the Birdy frame accept 20" wheels as mounted on the Birdy R20 11SP.

And I can also compare with the Moulton since I have two Moulton, A Jubilee and a Speed, the Speed being the lightest and fastest Moulton.

linberl

Obviously it is subjective, but "fast" is not my only criteria for ride quality. YMMV.

Jipe

Indeed, I agree with you, ride quality is very important and this is the other advantage of the Birdy wrt. the Brompton: the Brompton feel a little twitchy the first time you use it while the Birdy is perfectly stable and behave like a big wheel bike. Its part of the higher efficiency of the Birdy.

About the Brompton titanium clones, I agree with GTA: these aren't a good solution because its not possible to just swap steel tubes for titanium tubes without changing anything to the frame design, the new T-line with its frame fully re-designed for titanium should be much better.

pinholecam

You never mentioned your use case.
That will make it easier for people to help you narrow down on the bikes
But this question seems to be only asking about how a Brompton with 3rd party Ti parts will be like. (in which case GTA already gave the most relevant answer to it )

FlamingTux

Folks, looking for any new recent experience with full builds and / or main frames from EasyTi. Please post in ' Titanium Ultralight 16-inch wheel folding bikes - Looking for leads on suppliers'