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We are going bike riding the UK in May for the 40th wedding anniversary. We want to have the whole trip paid off before we leave. With this in mind I have come up for my own rules and goal for this winter build.
1. I can't buy anything, I gotta use what I got
2. No stealing of parts from any of my already built bikes, I can only use junk that was in my scrap trailer
3. Its got to be something I will use
4. I don't have a lot of time so it has to be simple and I have to get the project out of our family room so we can ride the indoor bicycle trainers to to get ready for the UK
5. I don't have an indoor workspace so it will have to be small
6. It's got to be fun to ride
7. To come in last in the winter build off
I went to camp and emptied my scrap trailer. I have a lot of cheap bikes in there, road, mountain, five 20 inch bikes and one 16 inch. Two of the 20 inch bikes are the same. The 20 inchers are all cheap, all steel and heavy. I measured up the frame geometry on all the 20 inch bikes and the one that I have a duplicate for is the closest to a 20 inch mod trials bike. There are a lot of sites on the net that list the specs for trials bikes or the ideal specs. Here is a comparison with my chosen 20 inch bike and the basic ideal geometry for a 20 inch mod trials bike.
1. Wheel base = 930mm with 980mm to 1030 ideal
2. Bottom bracket rise = 10mm with the ideal being 0 to 100mm
3. Chain stay length = 360mm with ideal being 350mm to 395 which is great as this is the hardest to modify
4. Axle to crown = 320mm with ideal being 360mm to 390.
5. Fork off set = 25mm with ideal being 25mm to 45.
If I use a 26 inch fork I can improve the geometry, providing the one i have fits OK.
1. wheel base would now be 970mm
2. Bottom bracket rise would now be 30mm
3. Axle to crown would now be 400mm
4. Fork off set would now be 25mm
A fork from a 24 inch bike might be better but I must have recycled them all in an earlier purge as I can't find any 24 inch parts, nuts.
I have a freewheel that works on the bottom bracket like trials bikes but it is on another bike so I can't use that. I am not going to make a bottom bracket bash plate or a bash plate for the sprocket. A common drive ratio for a 20 inch mod trials bike is 1 to 1.5 18x12=1.5. The closest I can come with what I got is 1 to 1.59 using 30x19. This is a big front cog and would be prone to bashing but I am going to be using this bike to improve my balance and anyway it will be way to heavy and have subpar brakes for any bashing.
With all this in mind I am going to attempt to toss together a REASONABLE FACSIMILE THEROF for a 20 inch mod trials bike. I hope this meets all the winter build off rules as it is not really a muscle bike? Let me know if this isn't OK before I start to build it. Thanks.
1. I can't buy anything, I gotta use what I got
2. No stealing of parts from any of my already built bikes, I can only use junk that was in my scrap trailer
3. Its got to be something I will use
4. I don't have a lot of time so it has to be simple and I have to get the project out of our family room so we can ride the indoor bicycle trainers to to get ready for the UK
5. I don't have an indoor workspace so it will have to be small
6. It's got to be fun to ride
7. To come in last in the winter build off
I went to camp and emptied my scrap trailer. I have a lot of cheap bikes in there, road, mountain, five 20 inch bikes and one 16 inch. Two of the 20 inch bikes are the same. The 20 inchers are all cheap, all steel and heavy. I measured up the frame geometry on all the 20 inch bikes and the one that I have a duplicate for is the closest to a 20 inch mod trials bike. There are a lot of sites on the net that list the specs for trials bikes or the ideal specs. Here is a comparison with my chosen 20 inch bike and the basic ideal geometry for a 20 inch mod trials bike.
1. Wheel base = 930mm with 980mm to 1030 ideal
2. Bottom bracket rise = 10mm with the ideal being 0 to 100mm
3. Chain stay length = 360mm with ideal being 350mm to 395 which is great as this is the hardest to modify
4. Axle to crown = 320mm with ideal being 360mm to 390.
5. Fork off set = 25mm with ideal being 25mm to 45.
If I use a 26 inch fork I can improve the geometry, providing the one i have fits OK.
1. wheel base would now be 970mm
2. Bottom bracket rise would now be 30mm
3. Axle to crown would now be 400mm
4. Fork off set would now be 25mm
A fork from a 24 inch bike might be better but I must have recycled them all in an earlier purge as I can't find any 24 inch parts, nuts.
I have a freewheel that works on the bottom bracket like trials bikes but it is on another bike so I can't use that. I am not going to make a bottom bracket bash plate or a bash plate for the sprocket. A common drive ratio for a 20 inch mod trials bike is 1 to 1.5 18x12=1.5. The closest I can come with what I got is 1 to 1.59 using 30x19. This is a big front cog and would be prone to bashing but I am going to be using this bike to improve my balance and anyway it will be way to heavy and have subpar brakes for any bashing.
With all this in mind I am going to attempt to toss together a REASONABLE FACSIMILE THEROF for a 20 inch mod trials bike. I hope this meets all the winter build off rules as it is not really a muscle bike? Let me know if this isn't OK before I start to build it. Thanks.
