Sunday, February 6, 2022

United Trifold: General Comparison with Brompton

Since borrowing the stock Brompton M6R from my friend, I have done a lot of comparison with the United Trifold. I compared the folded size, the difference in parking mode, and now I will do a general comparison of the geometry and overall appearance.

After doing all these comparisons, I can appreciate how much more refined the Brompton fold is. There are many details that contribute to the compact folded size, but they are not apparent without a side by side comparison.

On the Brompton, distance between frame roller wheels are 13 cm.

On the United Trifold, distance between frame roller wheels are very slightly narrower at 12.5 cm. Note the new coil spring suspension.

However, the rack roller wheels on the United Trifold are much wider apart, at 17 cm versus 14.5 cm on the Brompton. Good for stability but not for compactness. Note that one of the roller wheels on the Brompton is located inside the rack, not on the outside.

On the United Trifold, distance between frame and rack roller wheels is 37.5 cm.

On the Brompton, distance between frame and rack roller wheels is 43.5 cm.

Side by side comparison of the full bikes.

Brompton rear rack is tilted downwards, which helps to reduce the folded size.

Brompton rear rack extends all the way to the end, as compared to the United Trifold.

View of the rear racks. On the Brompton, the rear wheel slots in between the rack openings, which helps to reduce the folded size.

The Brompton saddle rails allow the saddle to be pushed further forward, to reduce the folded size.

Brompton front brake cable routes from the bottom, as compared to the United Trifold which routes from the top.

As the front wheel folds to the opposite side, the front wheel hooks are located on different sides of the fork as well.

Frame clamps are located on different sides as well, due to the opposite folding direction of the front wheel.

Brompton chain stay length is 410 mm

United Trifold chain stay length is slightly longer at 420 mm

Brompton wheelbase is 104 cm

United Trifold wheelbase is much longer, at 109 cm

Brompton front centre distance is 64 cm

United Trifold front centre distance is 69 cm

Brompton has a plastic latch for holding the handlepost when folded, while the United Trifold does not have.

Slight difference in top tube shapes. Bottle cage mount available on the United Trifold.

Very different headset and handlepost designs

The United Trifold is able to use standard Dahon/Fnhon style handleposts, which is much better for upgrading or changing the height.

United Trifold has the more modern handlepost and flat handlebar layout which forms a T-shape, while the Brompton uses the more classic riser handlebar design.

Brompton has a more delicate click box to shift the internal hub, and also the external pusher to shift across the external sprockets. Quite complicated to troubleshoot if you are not familiar with it.

From these detailed comparisons, we can see that there are many differences between the United Trifold and the Brompton. I appreciate the effort by the frame designer to try something different on the United Trifold, but only a few changes are improvements over the original Brompton.

Those improvements that I think are good are:
1) Dahon style 33.9 mm diameter seat post.
2) Dahon style handlepost with quick release folding lever.
3) Dahon style internal headset, can be easily changed to a Litepro headset.
4) 135 mm rear OLD to fit standard wheels.
5) Top tube bottle cage mount.
6) Aluminium frame, no more rust concerns.

As for the other changes, it did not make it better than the original Brompton design, so those changes are not improvements. Having owned both a Brompton and now a United Trifold, each has its own advantages and disadvantages.

The Brompton is the most compact folding bike, that is not in doubt. However, it is not an easy bike to modify due to many proprietary parts, although it does get easier nowadays with many third party accessories. I still cannot get used to the combined internal + external shifting logic.

The United Trifold wins in terms of easy upgradability, with more standard frame designs such as the rear 135 mm OLD and Dahon style handlepost. The aluminium frame and rear triangle is also much preferred by me as it will not rust.

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