Adler Junior M100

Adler Junior M100

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Just like many motor cycle producers across Europe in the mid-1950s, Adler began to experience their sales slipping away as the improving social situation found people with more disposable income, so a growing demand for cars was progressively replacing motor cycles. British, Italian and French motor cycle manufacturers were all facing exactly the same position as the German industry and, like many other builders, Adler sought economic refuge in an unlikely but fashionable alternative product: the scooter!

In 1955 Adler presented its new MR100 ‘Junior’ scooter, with 98cc fan-cooled 2-stroke single-cylinder engine, 50 × 50mm bore & stroke, rated at 3.75HP, with three-speed foot changed gears.

The van arrives with our test machine, and this certainly looks like a very big and heavily constructed scooter! Is this really just 98cc? We recruit some assistance with the unloading, since this isn’t the usual sort of small capacity lightweight anyone might be expecting to manhandle on their own. Down to ground level, we roll ‘Junior’ straight onto the scales, 7stone front + 10stone rear = 17stone (108kg), which is quite a substantial load for a low power 98 to be hauling about. There’s certainly no economy of materials going on with this bike!

The body shell was originally finished in light blue-green metallic with dark blue pinstripe but, with the passage of time, has faded to a pale green and surface rusted patina, now seemingly preserved under a lacquer seal.

Adler’s nacelle carries a Hella headlamp and a big & showy aluminium-faced Noris horn. The rear, however, mounts a Lucas 529 taillight, which would have been the original fitment for the UK, since a matching Hella rear lens for the continental market wouldn’t have had a clear port to illuminate the rear number plate as required in the UK. A British market lamp would probably have been fitted at point of sale. Adler Junior scooters were imported and listed in the UK from 1956, so this Lucas lamp would be considered original equipment in this country.

There’s a lockable toolbox inside the front apron, and a cast alloy bag catch fitted below the steering stem lock. An aluminium cast central handlebar clamp tops the steering stem, which goes down through the body-shell headstock to a substantially-constructed Earles pattern front suspension set. Spoked wheels are shod with 3.00×14 front and 3.25×14 rear tyres. A pressed steel guard fully encases the chain final drive, so this is a scooter built with practical intentions of use under all weather conditions.

The rear footplates stick out from the body-shell almost like a pair of wings, or the tail plane fins of a missile, though Junior’s incongruous and bulbous body panels are hardly sleek or dynamic to match this delusion—less like a jet, but more like a cargo truck! The wide and protruding rear footplates are one of Junior’s most striking features in more ways than one—not only as a visual oddity, but as an ever present hazard when navigating the machine, or when walking by the bike, since you know they’re just waiting for some absent moment when you drop your guard, to bang your ankles painfully or skin your shins.

Sparking plug service is accessed through the front engine inspection cover, which is also where you’ll find the petrol tap switch hiding in the gloom. Turn for off–on–reserve. There’s a choke trigger under the right-hand cluster, then just putting the key straight in the lock engages an ignition lamp in the speedometer. No use looking round for a kick-start, there isn’t one… the only starting method on this Adler Junior is electric starting, and how ambitious was that for the mid 1950s? Push the key in to activate the dynastart motor, which turns the engine with a steady bloop, bloop, bloop… a couple of half-hearted coughs… then the motor rumbles into life with a low burble.

The engine runs with a flat exhaust note, producing a deep-frequency vibration, and generally gives the impression of a low compression and low revving motor. Twin exhaust silencers are slung under the footboards like a pair of drop torpedoes, and smoke just seems to emanate from every direction beneath the bike, some rising in clouds around us, while other heavily oil-laden fumes roll away ominously at ground level like some volcanic pyroclastic flow… probably time we got out of here…

Pulling in the clutch we find the gear-change heavy, stiff and notchy; it really only seems to understand the firm application of a heavy boot to its heel-and-toe, rocking-pedal change. Neutral lies at bottom of the box, with 3 × heel-back selection to change up, then forward toe (more like stamp down with the ball of your foot) to shift back down the cogs again. Changing up from first to second, you sometimes find you’ve randomly shifted straight through two gears and into third.

Not really what you’d normally call acceleration as such, the torquey ‘building up’ of speed is lumbering and ponderous and, coupled with the industrial gear-change, very much imparts a crude and truck-like impression. Exhaust smoke billows liberally from seemingly everywhere underneath the footboard wings as we bumble up the road, giving the impression of some crippled bomber struggling back across the channel from the Battle of Britain. The rider of our pace bike looks incredulously amused and laughing hysterically at our plight as our Adler leaves a swirling fog-like trail of haze in its wake.

Settling to a happy cruising speed indicating 30mph (pace bike also showing 30), we’re beginning to wonder quite what kind of fuel is actually in the tank? Our only hope is that the oily vapours might abate as the engine gets hotter and settles down. By the time we’re approaching the three-mile marker, the worst of the oil smog has begun to clear from our smoky old bonfeuerwehrwägen, so, presuming the motor might now be worked up to temperature, we crouch into the cockpit and go for our best on-flat paced run—speedometer indicated 36–37mph, which the pace bike clocked at 35. Downhill run indicated 40mph, and pace bike also confirmed it at 40.

Adler’s speed for the 98cc Junior was given as 65km/h or 40mph, so we considered our test results reasonably representative for a nearly 60-year old machine. As expected and due to the bike’s weight, the low compression motor faded dramatically on the uphill climb and obviously wasn’t going to complete the ascent in top (third), but by the time resistance from the reluctant gear-change had been overcome while the speed continued to fall away, and we’d finally managed to crunch it back into second, Junior only managed to crest the brow at a miserable 15mph.

Main lighting is switched by turning the ignition key, leaving the left-hand cluster simply arranged with just the horn button and a beam–dip switch. It’s very much basic controls only, there’s nothing fancy here, purely function and not much luxury in the 1950s.

The petrol tank filler is found beneath the enormous Denfeld dual seat, which at 25 inches might even seem long enough for a whole family and the dog!

We don’t know whether Adler actually fitted a centre-stand; our test bike doesn’t have one, but there’s a lug under the frame that looks as if it might have been intended for a stand, though it doesn’t show much indication of ever being used. Our Adler has a prop stand tucked towards the back under the left-hand footplate, but this proves really difficult (practically impossible) to tag down with your foot, so you invariably end up groveling under the bike to try and find the wretched thing, which seems rather unlikely, so we’re not entirely convinced whether this was an original fitting or not.

The half-width hub front brake was weak, the half-width hub rear heel-back brake was very poor, and you could sometimes find yourself lifting off the saddle if you were really wanting to stop at a junction. Considering the heavy weight of this scooter, braking really wasn’t up to the capability we’d be expecting of Adler’s build quality reputation, so there’s some feeling the lack of performance might be put down to the drums needing an overdue service.

Intrigued as to what might actually be lurking inside the voluminous rear body section, we set about raising Adler’s shell to have a look at the mechanics beneath. This task isn’t anything like simply removing the side-panels from a comparable Italian scooter, since Adler’s body is basically a one-piece shell with a few small inspection ports. Nor does it hinge back like the DKW Hobby body-shell. With the Adler you have to remove several bolts, and disconnect wiring though the left-hand porthole, then lift the entire body-shell completely off the bike-and it’s very heavy! This really isn’t a one-man job, and you most certainly wouldn’t want to be struggling with this task by the roadside.

Beneath the exoskeleton, the engineering’s impression is substantial and primitive. The motor looks like a proper quality industrial job with its cast alloy fan-cooling shroud. There are two batteries (one each side for balance maybe) to support the electric start, but that rear suspension swing-arm arrangement doesn’t look very high-tech.

Adler Junior looks like a truck, weighs like a truck, rides like a truck, performs like a truck, and seems to be made like a truck—conclusion, it’s a truck!

The 12-Volt dynastart equipment set must be a significant contribution towards making this about the biggest and heaviest under-100cc scooter that anyone has ever built, but what a bold decision for Adler to have made by producing their scooter without any back-up starting means as far back as 1955, and to rely solely on electric starting!

Our lasting impression was that the 98 Junior was very much overweight and underpowered. The 98cc Junior scooter was joined by a 125cc Junior Sport model in 1956, of 54 × 54mm bore and rated at a healthier 7HP for, presumably, a much better performance.

Dane techniczne:

Make Model.
Adler Junior M100
1 cylinder 2 stroke
98 cc / 6 cub in.
Bore x Stroke
50 x 50 mm
Air cooled
Petrol oil mix 25:1
Multi plate wet cable operated
Single built into block
Exhaust System
Twin steel
Max Power
2.8 kW / 3.75 hp
Compression Ratio
1: 5.75
3 Speed gearbox foot changes
Final Drive
Double cradle steel frame
Front suspension
Leading link
Rear suspension
Twon shock plunger
Front Wheel
3.00 x 14 in
3.25 x 14 in
Drum 125 mm
Wet Weight
108 kg / 238 lbs
Fuel Capacity
7 L / 1.8 US gal
Top Speed
70 km/h / 43.5 mph
Light Blue-Green metallic