nzvet
03-30-2008, 11:14 PM
From my last mid-racer build (SWB Marauder) I wanted to try and improve the aerodynamic position of the rider and make the overall weight 3-4kg’s lighter. I wanted to design this bent for longer distance rides.
Photos:
http://s151.photobucket.com/albums/s156/nzvet/SWB%20MK2/
Initially I was going to build a high-racer but at my height of 5’6” I was concerned about my ability to easily touch the ground. I therefore chose to attempt a high-racer seat to BB position in a mid-racer frame.
I started with a 2” tube and used the rear triangle from an old 10 speed bike. Had to play around with the main tube / chain stay angle a bit to get the chain, seat, and fork clearance just right. The wheel base finally came out at 1300mm. I ended up with a 220mm BB to seat height difference which was what I was after. At his point the frame alone weighed 4kg’s being 2kg’s lighter than my last frame.
I’ve used a 700C fork to give height and this allows me to later try a 700C front wheel (rear wheel is also 700C). I used the wheels I’d previously built for my last mid-racer. The rear is a 32 spoke Mavic CXP33 rim, Ultegra hub and Maxxis Detonator 28C tyre. The front is a Sun 36 spoke 20” 451 BMX rim, dabomb hub and a Schwalbe Stelvio 1’1/8” tyre. The Tektro Mini-V’s make very effective front brakes.
The steering geometry is similar to a DF road bike with the head tube at 72 degrees.
I’m a fan of the clean cross chain configuration which the Terra-Cycle idler controls well. The seat is 3 layers of 6mm bendable ply glued with epoxy and glassed. Although comfortable and rigid I ended up losing my weight advantage essentially gaining back the 2kg’s – doh!! Have just ordered a Volae seat to solve this. The carbon fibre version is 25% of my current seat weight. I’ve improved the ease of transporting the bike by using quick releases on the seat. This worked out extremely well!
SRAM Attack grip shifters take care of the 53/39 chain ring (165mm cranks) and 32-11 cassette. The rear brake is an Ultegra calliper.
The Topeak MTX Trunkbag DXP gives heaps of luggage capacity and seems to improve the aerodynamics. To save on weight I’ll likely do away with the carrier for events and use a lighter seat bag.
Out on the road the handling worked out better than I expected. The steering is neutral at all speeds. I’m delighted with the result!
With the new seat I anticipate the weight to reduce to 12-13 kg, down from 16kg’s.
The idea is to train up and enter an Enduro event at the end of the year.
A bit of riding to do before then!
Next project: Marauder Reloaded??
Photos:
http://s151.photobucket.com/albums/s156/nzvet/SWB%20MK2/
Initially I was going to build a high-racer but at my height of 5’6” I was concerned about my ability to easily touch the ground. I therefore chose to attempt a high-racer seat to BB position in a mid-racer frame.
I started with a 2” tube and used the rear triangle from an old 10 speed bike. Had to play around with the main tube / chain stay angle a bit to get the chain, seat, and fork clearance just right. The wheel base finally came out at 1300mm. I ended up with a 220mm BB to seat height difference which was what I was after. At his point the frame alone weighed 4kg’s being 2kg’s lighter than my last frame.
I’ve used a 700C fork to give height and this allows me to later try a 700C front wheel (rear wheel is also 700C). I used the wheels I’d previously built for my last mid-racer. The rear is a 32 spoke Mavic CXP33 rim, Ultegra hub and Maxxis Detonator 28C tyre. The front is a Sun 36 spoke 20” 451 BMX rim, dabomb hub and a Schwalbe Stelvio 1’1/8” tyre. The Tektro Mini-V’s make very effective front brakes.
The steering geometry is similar to a DF road bike with the head tube at 72 degrees.
I’m a fan of the clean cross chain configuration which the Terra-Cycle idler controls well. The seat is 3 layers of 6mm bendable ply glued with epoxy and glassed. Although comfortable and rigid I ended up losing my weight advantage essentially gaining back the 2kg’s – doh!! Have just ordered a Volae seat to solve this. The carbon fibre version is 25% of my current seat weight. I’ve improved the ease of transporting the bike by using quick releases on the seat. This worked out extremely well!
SRAM Attack grip shifters take care of the 53/39 chain ring (165mm cranks) and 32-11 cassette. The rear brake is an Ultegra calliper.
The Topeak MTX Trunkbag DXP gives heaps of luggage capacity and seems to improve the aerodynamics. To save on weight I’ll likely do away with the carrier for events and use a lighter seat bag.
Out on the road the handling worked out better than I expected. The steering is neutral at all speeds. I’m delighted with the result!
With the new seat I anticipate the weight to reduce to 12-13 kg, down from 16kg’s.
The idea is to train up and enter an Enduro event at the end of the year.
A bit of riding to do before then!
Next project: Marauder Reloaded??