I've got a Dahon Speed Uno that's about 4 years old that's used for a 3 mile ride to and from work daily, and it's been beaten on quite a bit over that time frame. The folding frame is wearing (most notably in the handlebar hinge), the cranks are starting to have issues, the pedals have needed to be replaced twice, now I need new wheels, etc.

So basically, I'm looking at buying a new bike instead of putting the money into repairing the old one. First of all, I love the simplicity of the Speed Uno that I have, and in general I take it around the city with no problems. The main areas where I use it are mostly flat. Even still, sometimes on large hills I miss having another gear to shift to. Because of this, the Tern Duo models that use the SRAM Automatix seem nearly perfect for me.

The problem is that I have seen zero reviews anywhere (on this forum or elsewhere) of either model. There must be people who have these, right? What do people think of them? Does the automatic shifting help, or is it more trouble than it's worth?

I would lean towards the Swoop Duo because I'm used to a 20" bike, but also noticed that there seems to be conflicting information on the gearing of that one. Tern's specs page says 48"-58", and Tern's store page says 29"-80". I'd have to assume that the latter listing is a typo talking about a bike with more gears, but I'm not entirely sure. Anyway, my Speed Uno is 64" for that, and I would be mildly disappointed if the Swoop Duo would be 58" and (in my limited understanding of it) go slower at the same RPM.

The Castro Duo (57"-69") seems like maybe it'd be better for higher speeds, and I have to admit that there are definitely times I'm jealous of the people passing me by on the road.

Well, the 48"to 58" spec would be wrong also.. the Automatix is a 137% overdrive 2 speed .. 58/48 would be 120% .. the 57"to 69" is also wrong at 121%

So if you are contemplating either bike, get the dealer to count the teeth on front and rear sprocket, then factor in tire size and get an accurate gear inch..

I've been running that hub for years.. nice hub, but it needs to be adjusted to keep from 'early shifting' .. the hubs were designed for large wheeled bikes, but got ported to the small wheelers.. you can read about some of my bikes Here and Here

swoop 48 58
castro 48 66 the castro has 24 inch wheels hence its faster with 66
at least that's what im told

Well, if the Castro has a 48" bottom gear, then 66" would be correct for the top (137% increase) .. if the Swoop has a 48" bottom gear then it will also have a 66" top (137% increase).. there's a problem with the accuracy of the Tern literature.. using 66 gear inches, different wheel sizes will yield the same top speed given the same cadence, just the smaller wheel will be spinning faster than the larger one ...

Castro ... 38 in the front 16 in rear with 24 inch wheels. Gear inches is 57 - 78
Swoop ..38 in front 16 in rear with 20 ( 406 ) wheels Gear inches 44 - 60
again that's Gear inches from Sheldon Gear calculator and I run out in the stinking hot warehouse and opened a couple boxes and counted teeth ...

Thor

Excellent job!.. top marks! Gotta feel better now knowing the truth ..

Definitely appreciate the information there. It'd be nice if the manufacturer website had accurate information to prevent the need for this, but I guess that's asking too much of them.

I'm still pretty sure I'll be getting one of these two, but I have to admit I find the complete and utter lack of reviews or even owners on a forum with as large a group of folding bike enthusiasts as this one is to be very odd.

I think I'm leaning towards the larger Castro but might still change my mind on that.

Review: Tern Castro Duo | Bicycle Times Magazine