The latest creation from Mike Burrows combines asymmetry and rhetoric like never before. The Ratracer SL (Street Legal) appears to be very simple at first glance, but it’s so brim-full with innovation and original thinking that it makes all standard uprights look totally archaic. Burrows is again a welcome breath of fresh air in the cycling world.
Those who remember Mike’s controversial TCR (TIG-welded compact road bike) and the ructions it caused with the UCI (the world governing body for professional cycle racing) will also acknowledge that early sceptics of the design didn’t wait too long before jumping on the bandwagon. It was just after the UCI approved compacts, if I remember correctly.
But while virtually every road bike and mountain bike frame now has a sloping top-tube, it will be interesting to see if the recumbent world accepts Mike’s new take on the front-wheel drive (FWD) form. Not that FWD is unusual – most bikes had it before the birth of the Rover Safety Cycle – which is effectively what we all ride now – in the late 1880s.
However, despite its early popularity and subsequent demise because of the cloning restrictions imposed by the UCI and complete adoption of the diamond frame, FWD does have some compelling advantages…
Beautifully simple and elegant, the Ratracer concentrates the engineering trickery into a small area adjacent to the rider’s thigh, hidden beneath a carbon fibre cover. The test frame is constructed in two parts and welded together, but the production models will be made from one-piece 6000-series aluminium alloy.
There are many advantages of FWD on a recumbent. The chain is obviously shorter, doesn’t trail near the ground and won’t foul the front wheel when turning. The gear cables have a much shorter run and also suffer less fouling from road muck. Torque-steer (where the rider’s pedal inputs affect the steering) can be designed out by using a hub gear. Derailleur systems induce torque steer, because the chain line is able to move out of parallel to the steering axis, making torque steer worse in some gears.
With most of the mechanics occurring in one place, the rest of the ship is very simple. Despite the obvious 90-degree chain bend in most FWD bikes, the losses in efficiency over one large diameter roller can be less than those incurred with a low, rear-wheel drive racing recumbent with multiple pulleys taking the chain over the front wheel and under the rider. Upright bikes often suffer from bad chain lines, which can be just as inefficient as losses in hub gears, for instance.
To counter the above, several disadvantages almost, but not quite in my mind, balance the equation. Traction can be elusive on poor or uphill surfaces; wheel removal is very tricky, especially with the necessary chain tensioner; there’s the torque steer mentioned above on some designs; and the extra complexity when considering front suspension.
However, Mike seems to have overcome the technical hurdles to produce a very graceful rear end to his frame. The stubaxle design uses a casting similar to his rear-wheel drive trike (the Speedy), leaving the flowing lines of the seat frame ample clearance for adjustability via a clamp and must-have jubilee clip arrangement.
An excellent, all-round set-up The Ratracer is designed as a Sunday driver/pleasure bike and as such has very accessible handling. Most who tried it didn’t fall off and even rank newcomers could ride it after the usual self-imposed kamikaze stunts. The short wheelbase means that it can be flicked around corners at speed, while still pedalling of course, and the 24in wheels gave an instant confidence compared with 16 or 20in equivalents.
Despite there being no definitive front-end geometry for a recumbent, mainly because there’s no such thing as a definitive recumbent, the Ratracer has an 80-degree head angle with straight forks, which yields about 40mm of stabilising trail. Comparing this to a road bike’s 60mm of trail is a bit pointless because the Ratracer isn’t a road bike – there are other factors that have to be taken into consideration. Weight distribution is between 60:40 and 55:45 front to back.
This is obviously different to a road bike, which may well be the reverse. There’s also a school of thought emerging that says standard trail calculations should be factored in to take into account small wheels and their lack of inertia. Using 24in wheels helps things feel and ride a little more ‘normal’ in the Ratracer’s case.
For tall riders a longer boom will preserve the frontal weight bias and avoid the corrupting effects of adjusting the seat back along the main frame. However, for general use the seat will accommodate a large range of leg lengths and is easy to adjust.
The most striking piece of kit on the Ratracer is the elegantly swooping seat with its curving headrest and suspension strut – although looking at the seat cover gave me a flashback to a multicoloured jumper my trendy aunty gave me one Christmas. Nevertheless, the execution is perfect because the width sits between the shoulder blades and the curvature allows all sizes to find a comfortable riding position. The neck support is welcome due to road shock reaching parts of the body that doesn’t on ordinary bikes.
Ready for another shock? The cranks are just 150mm long! This is intentional and aims to reduce load on the knees with a smaller bend at maximum load. It also encourages spinning (you have to change down to produce the same power with the reduced leverage) and is more aerodynamic, which also means more room inside a nose faring if you want to go seriously fast. The only time I noticed the shortness was when pulling away – on one occasion the lack of familiar oomph left me in an embarrassing mess in the road.
Shimano’s 8-speed hub has a good spread of gears and mounting the shifter on the lefthand handlebar means you twist back for easier gears. Save for a delay in drive take-up on some occasions, the hub produces silent operation and slick changes to get up to speed.
Bearing in mind the front-biased weight distribution and the odd chance of wheel spin, Mike has used a chunkier front tyre at the front. The 507x32mm 100psi-rated Vee Rubber which is also used successfully in the new Airnimal Joey Commute.
The rear tyre has a much easier time, so a lighter 520x23mm 145psi-rated Schwalbe Stelvio is used. I don’t see incompatibility as an issue because the same narrow rear tube could be carried as a spare. Both rims are strung with 36 spokes and should therefore be good and strong for the odd pothole, especially as both rims are semi-deep section.
Behind the carbon cover the drive side of the chain (top) runs over a 3in spindle, and the return side runs over a 2in spindle (below), which is sprung to tension the chain and make dropping the wheel out easier
The front Shimano Alfine disc provides powerful stopping power needed on a FWD machine
A 70mm Sachs drum brake makes for a beautifully clean, maintenance-free back end
Toxy range – ZR from £1,295
ZOX FWD recumbents – from £433
Toxy’s range comes reasonably close to the Ratracer being FWD, but all the Toxy range comes with suspension. The ZR looks like a very potent FWD racer. www.toxy.de
ZOX make fully rigid and amazingly minimalist FWD recumbents, including tandems. As with Toxy, there’s no apparent UK importer yet. www.zoxbikes.com
|Name||Name, 0, 10, Name, Ratracer SL|
|Brand||Brand, 0, 20, Brand, Mike Burrows|
|Chain||Chain, 2, 0, Chain, Shimano Tiagra|
|Frame Material||Frame Material, 2, 0, Frame Material, Alloy|
|Front Hub||Front Hub, 2, 0, Front Hub, Alfine|
|Front Tyre Size||Front Tyre Size, 2, 0, Front Tyre Size, 507x32|
|Head Angle||Head Angle, 2, 0, Head Angle, 80|
|Rear Tyre Size||Rear Tyre Size, 2, 0, Rear Tyre Size, 520x23|
|Weight (kg)||Weight (kg), 2, 0, Weight (kg), 14|
|Year||Year, 2, 0, Year, 2007|
|Chainring Size (No of Teeth)||Chainring Size (No of Teeth), 2, 0, Chainring Size (No of Teeth), 42|
|Wheelbase (cm)||Wheelbase (cm), 2, 0, Wheelbase (cm), 115|