All images courtesy of Jon Ashelford Having ridden 'Thumper' for just over two weeks now in many conditions I thought I'd post up some sort of review. To start with, as most will know, this is by far the longest bike I have ever owned, and so its taken me a while to get used to. At 1065 it's pretty much average length and the +20 bb really is nothing special; what is special is all these things made out of steel. I'm not saying its never been done before but the feel of a bike this long and with such a diverse geometry (compared to what Leeson are often associated with producing) is really quite odd. But in a good way. Obviously the length has opened up a whole world in my riding, taps and sidehops coming far easier and cleaner than previously. Harsher moves such as gaps to front and drop gaps are also smoother on Thumper than on other alu counterparts I tried during the development stages, the patented Leeson straight-torque stays and tubing having helped create the rigidity in the bike that allows the smoothness at this level. Yet at a wet and windy hampshire comp the bike was surprisingly stable and agile, dealing with most extreme situations relatively easily, the short and stiff stays keeping the bike steady on the backwheel whilst the very narrow frame dealt with steep roll downs surprisingly easily. Interesting points about Thumper's geo: 72degree headangle with 110mm headtube - combined with the Echo Urban forks specced on Thumper - and again being produced in steel - taps, hooks, gaps to front and other moves relying massively on the stiffness of the front end are progressivley easier than previous Leeson designs. 3.75" frame height - one of the smallest frames around, yet with the triangular torsion bars between top and down tubes and chainstays extending into the down tubes, massive amounts of strength are retained, and of course stiffness. Torsion gusseting - designed as mentioned previously to strenghten the frames minute size, yet also to act as a go between, allowing the top and down tubes to work in unison, so as one will always be in compression whilst the other in tension, equally dispersing load throughout the frame. 380-5mm stays with slotted 360 dropouts - allows for the hub, almost like in an eccentric dropout, to be moved 5mm forwards and back in the frame to attain the right chain tension, yet still keeping the stiffness of the Leeson Patented 360 dropout. Patented topside tensioner - with gears rapidly becoming a thing of the past, and mech hangers seemingly only being a nuisance when a failed sidehop snaps them off, Leeson have innovated again using a simple piece of tough elastomer mounted from the TOP of the chainstay, pushing the chain down and retaining tension whilst being almost completely invulnerable from knocks and crash damage. Supersized ovalic (sp?) tapered seatstays - again reatain tension and strength whilst being ample support and mount for the Avid SD7 V brake. Extra BB shell - for prototype experimentation with +125mm bb rise. Just kidding... I'm running the frame with very basic parts and have to say that the change to a more UCI feeling bike has done me a world of good. The rear V is unbelieveable (run without a booster seems to work better) and the length and sleekness of the frame is something I've never been comfortable with in the past but have taken to now so happily, yet I still feel I really wouldn't be as comfortable on an Echo or Koxx, the feel of steel still being predominant in my style of riding. Quick rundown of specs and geo: Bars - Zoo!, Stem - Echo, Grips - Ritchie Foam, Forks - Echo Urban, Headset - FSA, Cranks - Middleburn RS7 Pro (20t), Pedals - Onza Hognesium, Chain - KHE Collapse, Front Brake - Avid BB7/XTR Lever/M4 rotor (185mm), Rear Brake - Avid SD7/XTR Lever/Plazmatic CRV, Front Wheel - Mavic D321/Hope XC/Maxxis High Roller, Rear Wheel - Sun Doublewide/Hope Pro IIt/Maxxis Minion/Shimano DX (17t). Wheelbase - 1065mm with Urban fork, BB Rise - 20mm, Frame Height (C to C) - 3.75inches, Headangle - 72degrees, Chainstay length - 380-5mm. Weight - Aprox. 25lbs. This is a prototype frame and as of yet will not be in production for some time (in the same way that Jon Shrewsburys '609Pirate' will also be), but hopefully if there is demand by July/August this year both frames will be in production by then. Aknowledgements in the development of Thumper: Mike Singleton (first concept design), Ali Clarkson (V-brake research and info), Nick Vaughan + Andrei Burton (geometry input), Adam Phillips (CAD) and Kris + Clive Leeson (Production and testing). Some pics of Thumper in action at a recent demo. Video coming soon... Rich
