Why would anyone want to pay much, much more for a lightweight folding bike? We get asked this quite often by big burly types.There are two primary markets,the obvious one being smaller people looking for something light and easy to hoik up into a car boot for leisure rides.The other is much more interesting stuff,and goes right to the heart of what we’re about and what we believe,because a lightweight folding bike takes the user into a new world of seamless, effortless integrated transport. Once you’ve ridden one of these bikes on city streets,hopping on and off, and vaulting onto trams and trains, you will be hooked. In the leisure market, a kilogramme here or there is of little consequence, but if your folding bike is your primary means of transport, you too will be prepared to pay big money to make it as light and convenient as possible. These are the lightest bikes around,if we omit custom Bike Fridays and esoteric folders like the Sinclair A-bike.We’ve tested both the S2L-X and Mu before in slightly different form.The Mu replaces the lightweight Helios SL we tried in August 2004 ( A to B43 ), we had a brief go on the Brompton S2L-X in April 2005 ( A to B47 ) and have since built our own super-lightweight derivative ( A to B49 ). Here we test them together for the first time. Is there are a clear best buy?

Fun to Ride

Lightweight bikes are undeniably fun to ride,but the widely held belief that they offer higher speed and nippier acceleration is mostly myth. If a bike weighs 12kg and the rider 70kg, reducing the weight of the bike by 2kg will shave little more than 2% off the gross weight,so performance will be broadly the same.But these bikes certainly feel faster than their more portly cousins.Why? No doubt there’s a psychological effect here: these lightweight machines feel sharper,and presumably that sportier feel encourages more spirited riding.

..in the world of Brompton oneupmanship, this bike has it all… but a passerby would never know…

Both are derived from standard models in production for decades, but the S2L-X and SL couldn’t be more different.The Brompton is neat and understated,the only obviously sporty feature being the low,straight ‘S’ type handlebars.But in the world of Brompton oneupmanship, this bike has it all:titanium seat pillar,rear frame,front forks and mudguard stays,Schwalbe Stelvio tyres,Jagwire cables,and a few other rarefied bits,although a passerby would never know.Concessions? It’s a normal Brompton in every respect, with full wet weather gear,front luggage carrier and everything else (except standard lights), but the S2L-X has only two gears,and they’re quite close ratios.You can fit wider ratios if you want ( A to B52 ),or choose from any of Brompton’s gear options (1,3 or 6 gears), but the single-speed is a bit limiting,and the others add weight,so the 2-speed is probably the best compromise.Like all Brompton variants,it has 16-inch tyres,which at 349mm, are almost 17-inch,and noticeably bigger than the 305mm ‘16-inch’ tyres common on Far Eastern bikes. The Mu SL looks pretty conventional too.Like the Brompton it has Stelvio tyres,but these are the next size up – 406mm or 20-inch.The bike has eight derailleur gears, but where Dahons are usually well equipped,the downside of the lightweight variant is a somewhat stripped down feel.The SL has no stand and no mudguards,which presumably won’t matter if it never rains again. More important,if you are hoping to do practical things with it, there’s no system for carrying luggage.

On the Road

Considering how different they are,the two bikes feel remarkably similar on the road.Both are rigid (the Brompton through those lower bars and the Dahon through a sturdier frame,stem and hinges),and both feel lithe and sporty.In traffic the Brompton’s 2-speed is slicker and easier than Dahon’s SRAM derailleur, but with a choice of only 56″ and 74″ gears,the Brompton can lag behind on hills.The Dahon has eight well-chosen ratios,from 31″ to 89″,which sounds like a clear advantage,but both these bikes respond well to standing out of the saddle on hills,so the lower gears are not as essential as they might sound. Presumably the bigger-wheeled Dahon rolls further and faster? As we were testing identical tyres,we went to some trouble to set the tyre pressures the same (60psi front and the maximum of 85psi rear) and test in identical conditions,but to our surprise the Brompton coasted slightly better,hitting 15mph against 14.7mph. The answer, presumably,is in the riding position.The ‘S’

…don’t go assuming that bigger wheels are better… Clearly they aren’t…

type bars are quite low,whereas those on the Mu give a more comfortable upright position. This increases the wind resistance enough to overshadow the slight bonus of the bigger wheels.Strange but true. Put these factors together and there’s another surprise.On our 10-mile commuter run the little Brompton was marginally faster,at 40 minutes against 41 minutes.It’s quite a flat circuit,so hills don’t really enter the equation,and at 15mph we aren’t riding particularly fast.Obviously hills and/or speed would tend to benefit the bigger bike,but don’t go assuming that bigger wheels are necessarily better.Clearly they aren’t. Although both these bikes are fun to ride and both nip along very efficiently, neither is particularly comfortable.The Dahon’s bigger wheels give a less choppy,more relaxed ride, but the handlebar grips stop the blood flowing to your fingers after a few miles.The Brompton counters with rear suspension, but we didn’t like the low‘S’ type handlebars which put far too much weight on your arms.

Folding

All right,we won’t keep you in suspense any longer…The Dahon is the lighter of the two,but at 9.5kg (21lb), it’s noticeably heavier than the 2004 Helios SL. On the other hand,it’s noticeably tougher too.The Helios was fitted with Rolf wheels which were said to be quite problematic, and it was certainly weaker around the hinge,stem and frame than the Mu,which feels a lovely solid machine.The Brompton weighs 9.7kg,exactly the same as the early production example we tried in April 2005. With folding, the honours definitely go the other way, as one might expect. We usually quote a folded size of 85 litres or 3 cubic feet for the Brompton. This is certainly achievable for smaller people, but if you prefer the saddle back and/or up,or you’ve fiddled with the handlebars or

…folding the Dahon is much simpler, and in this bulkier guise, any idiot should be able to master it…

brake levers,the folded size will grow. Set up for a typical rider of 5’ 9″,our test bike occupied 97 litres,or 3.4 cubic feet. Fit a taller seat pillar and the volume can exceed 106 litres (3.7 cubic feet). But against almost every other folder on the market,it’s unbeatable,and the folded package clips together really well.This makes it easier to carry and you can even sit on the folded bike on a crowded train, which is a real bonus. (If you fancy trying this,put the saddle stem right down and lock it with the saddle turned at an angle to create a comfy bottom-shaped seat out of the frame tube.) By contrast the Mu folds into quite a big package,and is noticeably longer than the older Helios.At 68cm it’s the same height, but 5cm longer (85cm) and 3cm wider (43cm). This results in a package of 249 litres or 8.8 cubic feet,which is big by any standards.On the other hand, the little magnetic catches that hold the frame halves together really work on this bike,where on more‘compact’ Dahons they never really make contact. Folding and unfolding the Brompton is easy once you’ve learnt the fold order,but can be confusing if you haven’t.The fiendishly clever folding pedal in particular (many folding bikes have two,but most,like the Brompton,only need one) can cause all sorts of aggravation for the inexperienced. Folding the Dahon is much simpler, and in this bulkier guise,any idiot should be able to master it.The magnets lightly clip the frame shut,and the handlebars fold down outside the package and are locked by a little plastic clip.But you do have to be careful,because if you miss the clip,the bars will clonk into the stem, which can be nasty. Once the Dahon is fully folded, you remove the MKS MTE demountable pedals (note, as above,that only one really needs to come off).These weigh 150g apiece, or 25g less than the MKS Promenade pedals fitted to the Helios.Demountable pedals are good and bad in equal measure.They pop off easily, leaving very little sticking out of the cranks,but the shafts are greasy,and you have to put them somewhere safe or the bike is rendered completely useless.On the other hand,the Dahon is a useful 300g lighter without them, so you only need to carry 9.2kg in one chunk.

Conclusion

We hate to be wimpy and weedy on this crucial question,but it really does depend what you want a folding bike for.The truth is,they’re both very good in their way… At £800,the Mu SL is much cheaper than the Brompton,which costs a delightfully precise £1,007.The Dahon is lighter too. For leisure rides where you don’t intend to carry more than a day bag,it’s a fine machine for the price. On the other hand, the Brompton S2L-X folds quickly and repeatably to less than half the size and is a much less cumbersome package on trains and buses.For a very small weight penalty,it comes fully equipped (except for lights),and it appears to be marginally the quickest of the two.

Specifications

Brompton S2L-X £1,007 .Weight 9.9kg (22lbs) . Gears 2-speed . Ratio 56”,74” . Folded Size H64.5cm L57.5cm W 2 8 . 5 c m . Folded Vo l u m e 96.7ltr (3.4 cu ft) .Wheelbase 105 c m Coasting Speed 15.0 mph. 10-mile Circuit 40 mins . Manufacturer Brompton Bicycle tel 0208 232 8484

Dahon Mu SL £800 .Weight 9.5kg (21lbs) . Gears 8-speed SRAM derailleur . Ratios 31-89″ Folded Siz e H68cm L85cm W43cm . Folded Volume 249ltr (8.8 cu ft) .Wheelbase 102 cm Coasting Speed 14.7mph . 10-mile Circuit 41 mins . Manufacturer Dahon Folding Bikes  mail sales@dahon.co.uk. UK distributor Fisher Outdoor Leisure  tel 01727 798345 mail sales@fisheroutdoor.co.uk

A to B 55 – Aug 2006