Hi all, sorry if this is a basic question. I’m planning to get a bike for my wife and need some advice on sizing. I’m currently riding a 20” ttrifold, and she has tried it and feels comfortable on it. However, based on what I’ve seen online, 16” trifold is usually recommended for someone around 160cm. In this case, would it be better to go for a 16” or stick with a 20”? Appreciate any advice, thanks!

If she feels comfortable on your 20" trifold then I'd suggest getting a second one. It's easier to manage things like tires and tubes if you both have the same size tires.

Fully agree with John, my suggestion is 20" and I will add on top that they have some advantages if you're not conditioned by the folding size: better rolling, better stability, and better comfort.

For a tri-fold from Brompton or a clone, actually the wheel size doesn't change the size of the frame, 20" and 16" have similar dimension when the bike is unfolded. Your wife will experience more or less the same position on a 16" and 20" clone with the same type of handlebar.

It only change the folded size and how the bike will roll on bad roads or trail where a 20" will perform better if it has wide tires (50mm or wider), 16" Brompton and clones have 35mm wide tires since their frame doesn't accept wider tires and anyway there are no wide tires in 16"/ETRTO349 (Brompton and clones 16" wheel size means ETRTO349, not the usual 16" = ETRTO305).

Note that many 20" clones do not accept wide tires, only recent one cloning the G-line accept 50-55mm wide tires like the G0line does.

Yes, wider tires will help adding better grip and comfort, but just the jump from 16" to 20", even with the same tire width, will improve the rolling on irregular surfaces, because the diameter increase helps to overcome some rough terrain easily. With a bigger diameter, it's like making the stones or the potholes smaller. If on top of that you have wider tires, you will add traction and comfort, but will add also some extra rotational weight.

This not my experience, Y had 3 wheelsets for my Birdy Titanium, one in ETRTO349 with 40x349 tires (Greenspeed Scorcher), one in ETRTO355 with 50x355 tires (SChwalbe Big Apple) and one in ETRTO406 with 32x406 tires (Continental Contact Urban, the Birdy frame doesn't accept tires wider than about35mm in ETRTO406).

The fastest was the 40x349 due to the very low rolling resistance of the Scorcher (these are high pressure, slick 40mm wide race tires), the most comfortable good on all type of roads, smooth or bad + trails and also fast the 50x355, the 32x406 wasn't as good as the two smaller and was less reactive.

Actually, the overall diameter with tires of 50x355 is about 455mm very close to the 470mm overall diameter of 32x406 (15mm difference = only about 3.19%).

Measurements show that with the same construction and same pressure, wider tires have a lower rolling resistance than narrow tires.

Rewrite this last part. 54x349?? What

My own experience as a longtime Brompton owner is that 349 wheels, and the Brompton, come into their own in heavy city traffic. I feel as though the bike could hold its own against all cars or other bikes. The wheels spin up to speed fast. You can weave well and cut through the traffic. Most of the time you are going between one light and the next in congested traffic. Downtown, Brompton is king.

That is indeed one of the principal appeals of the smaller 16" wheel family (305, 349, 355): easier acceleration and deceleration, and the spirited, lively feeling that comes with that. Add a short wheelbase and now you've got super agile, responsive handling and the ability to turn on a dime, coupled with spirited, jack-rabbit acceleration. This all makes for a very engaging, euphoric ride like no other, particularly apt for urban operations. Small wheel + short wheelbase = FUN


16" (349) wheels, 92cm wheelbase.

As for riding long-distance, long days in the saddle on these small wheelers, why not? I've done several 100km+ days in them. So long as you've got the physical condition and stamina, and the bike fits comfortably, it's fine. Here I am on long-distance, cross-country tour in South Korea on a 16" (305) small wheeler.

Ron, above, is known to run as small as 305 with really fat and deep section cushy tires, so rolling circumference that is larger than typical for that rim size. That said, without that, I'd recommend running 20"/406 wheels, because for me, that is the smallest wheel that will provide me a sufficient top gear, without using an Internal Gear Hub for an overdrive (like Brompton uses for their 16"/349 bikes), or a huge chainring or tiny high cog as some have done, I can use standard external-only gearing of 50/34 x 11-30. Now this is not going to give me a racer-high, only 85 gear inches, which is enough to pedal down mild grades not steep enough to just coast. Steeper, and I just coast. For my needed 21 gear inch low on 406, I need either my 34 x 30 (next cassette will have 34 or 36 low gear), or a large 1X cassette in the low 40s for low cog.

The above bike is an "occasional folder", with constant pannier use as a townie, so I need enough chainstay length (AND a rack that holds panniers behind the rear axle) for heel clearance; For a "frequent folder" for commuting, I might prioritize smaller wheels for more compact carry.