New tern compact folder: the BYB

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SA_SA_SA
Posts: 1889
Joined: 31 Oct 2009, 1:46pm

New tern compact folder: the BYB

Postby SA_SA_SA » 5 Mar 2020, 9:27pm

The new compact (but 20in) tern folder looks quite impressive (although no IGH option yet and the long cage derailleur idler is rather close to ground); sort of like a 20in brompton:

https://www.ternbicycles.com/bikes/byb

Given that tern make a hub dyno and integrated front lamp with rack rear lamp its a pity their (UK) video shows the byb with no lights in the dark....
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Brucey
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Re: New tern compact folder: the BYB

Postby Brucey » 5 Mar 2020, 10:04pm

Image

Image

I will go as far as to say that I quite like the look of the frame; it looks as if it might be less prone to cracking than a lot of aluminium framed folders, the fold is (despite being a bit more complicated than many) clever and provided the hinges are reasonably well made it ought to ride well. The BYB appears to have a longer wheelbase than many folders, despite which it folds into a small package, which also looks as if it is made to be wheeled along when folded. The initial impression is that it is not bad.

cheers
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mikeymo
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Re: New tern compact folder: the BYB

Postby mikeymo » 5 Mar 2020, 10:11pm

Brucey wrote:... it looks as if it might be less prone to cracking than a lot of aluminium framed folders,
cheers


I've actually got a Dahon Jack D7. But hardly ridden it. Do you have any knowledge/experience of cracking problems with this?

Cheers.
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Brucey
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Re: New tern compact folder: the BYB

Postby Brucey » 5 Mar 2020, 10:40pm

nearly all aluminium frames seem more likely to crack than comparable steel ones; welded aluminium is an inherently less forgiving, more fatigue-prone material. On top of this aluminium folding bikes (of all kinds) are more prone to problems of this sort than other aluminium bikes. The stresses in a Jack D7 will vary depending on the size of the frame that you use; the top brace position varies. I am not sure how common it is but I have seen a cracked 'Jack' with my own eyes. It was slightly different from the current model and it was very well used though (*).

To be sold at all bikes have to pass a test that ought to weed out the most inherently unsatisfactory designs. However this does not exclude both QA problems in manufacture and it takes little or no allowance for how the stresses in the frame might vary with a real rider on board, merrily wrestling with the handlebars etc. Bikes with a single spine in the frame are liable to be highly stressed when someone hauls on the handlebars. Cracks near the hinge welds in a folding bike frame are not uncommon.

My opinion is that many folders have frames that wouldn't pass muster as 'normal bike frames' (*) but are OK as folders simply because (like yours) the folder tends to do far fewer miles. A folder also commonly replaces other (more expensive) means of transport, so is seen to 'pay for itself' in a relatively short period of time. After a couple of years, get another one on the C2W scheme, why not? So a limited life expectancy is again more likely to be tolerated.

(*) The cracked Jack I saw had been used (by a keen cyclist) as 'the main bike' for several years, so it had done a lot more miles than most folders would have.

I would say that if you don't use a folding bike much, you arguably have practically nothing to worry about.

cheers
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mikeymo
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Re: New tern compact folder: the BYB

Postby mikeymo » 5 Mar 2020, 10:54pm

Brucey wrote:nearly all aluminium frames seem more likely to crack than comparable steel ones; welded aluminium is an inherently less forgiving, more fatigue-prone material. On top of this aluminium folding bikes (of all kinds) are more prone to problems of this sort than other aluminium bikes. The stresses in a Jack D7 will vary depending on the size of the frame that you use; the top brace position varies. I am not sure how common it is but I have seen a cracked 'Jack' with my own eyes. It was slightly different from the current model and it was very well used though (*).

To be sold at all bikes have to pass a test that ought to weed out the most inherently unsatisfactory designs. However this does not exclude both QA problems in manufacture and it takes little or no allowance for how the stresses in the frame might vary with a real rider on board, merrily wrestling with the handlebars etc. Bikes with a single spine in the frame are liable to be highly stressed when someone hauls on the handlebars. Cracks near the hinge welds in a folding bike frame are not uncommon.

My opinion is that many folders have frames that wouldn't pass muster as 'normal bike frames' (*) but are OK as folders simply because (like yours) the folder tends to do far fewer miles. A folder also commonly replaces other (more expensive) means of transport, so is seen to 'pay for itself' in a relatively short period of time. After a couple of years, get another one on the C2W scheme, why not? So a limited life expectancy is again more likely to be tolerated.

(*) The cracked Jack I saw had been used (by a keen cyclist) as 'the main bike' for several years, so it had done a lot more miles than most folders would have.

I would say that if you don't use a folding bike much, you arguably have practically nothing to worry about.

cheers


At the moment it's resting at the back of the "bike shed", which is something I knocked up with spare wood. It is actually waterproof, but one side is completely open to the elements. The last time I got as far back as the Dahon I noticed a bit of rust round the steerer/stem. It's got some unique er, "thing", that makes it easy to release the bars and rotate them 90 deg. You'd know what it is.

Question - does aluminium decay at all from being left exposed to changes of temperature and probably a bit of atmospheric moisture (but no rain)?

I rode it a few times, and there was sometimes a rather disconcerting creak from the hinge.

I bought it for a specific purpose, to commute from digs to theatre when I was doing a lot of touring, where you stay in one place for a week or two. It never seemed to get used though. And that's what I'd use it for again, if I fettle it. In car to somewhere, do the last 2/3 miles on bike. Or maybe a train (though as it's not a Brompton sized thing I daresay I'd end up arguing with staff).
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Brucey
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Re: New tern compact folder: the BYB

Postby Brucey » 5 Mar 2020, 11:05pm

aluminium can corrode; it turns into white powder not brown stuff which doesn't look as bad but is just as likely to assist with a breakage.

Any folding bike is better than no folding bike. Check for cracks and fettle away, what have you got to lose?

FWIW once your folding bike is in a bag it is (technically speaking) 'luggage' and different rules should apply. This means if you remember to simply carry (say) a bin liner with you (e.g. stuffed inside the seat pin), you should stand every chance of winning a 'folded bike size' argument with a jobsworth on a train, should the need arise.

cheers
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Cyckelgalen
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Re: New tern compact folder: the BYB

Postby Cyckelgalen » 6 Mar 2020, 10:13am

That new Tern looks awesome!

It is quite normal for folders to develop some squeak from the hinge. My Dahon Speed TR has a bolt that allows to adjust the clamp on both hinges, frame and steering. The Jack has probably a similar design. Normally the squeak disappears if you tighten the adjusting bolt a bit (a bit of grease on contact surfaces also helps), if it doesn't, it may be that the bushings in the hinge itself are worn. Check for play there. Dahon sell spares to rebuild the hinge.

There are some steel frame folders, usually more expensive, some aimed at the light touring market. The Dahon Speed Tr was one of the more affordable ones but it is not sold any more. I have subjected it to several couple-of-weeks tours, fully loaded with all the camping,cooking gear etc, and it has performed surprisingly well. The only flaws, it is a very heavy bike and, SRAM have discontinued the Dual Drive IGH and sell no spares to maintain it.

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Richard Fairhurst
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Re: New tern compact folder: the BYB

Postby Richard Fairhurst » 6 Mar 2020, 12:02pm

That looks really nice. A halfway house between a Brompton and a Bike Friday. I like the way it can go into a suitcase without any disassembly.
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iandriver
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Re: New tern compact folder: the BYB

Postby iandriver » 6 Mar 2020, 8:14pm

At £1299 to £2200, hmm. Perhaps not over the tried and tested brommie.
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UpWrong
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Re: New tern compact folder: the BYB

Postby UpWrong » 7 Mar 2020, 10:49am

It's rather on the heavy side I believe (14.3Kg), but if you can wheel it that will help.

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RickH
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Re: New tern compact folder: the BYB

Postby RickH » 7 Mar 2020, 6:07pm

UpWrong wrote:It's rather on the heavy side I believe (14.3Kg), but if you can wheel it that will help.

The 11 speed version is listed as 12.7kg, so is a bit lighter (but more expensive).