Luke has already posted the link... scroll back up to post #17 to find it... or just click here...
http://www.ratrodbikes.com/forum/index.php?threads/diy-slick-tires.64914/
Glen.
"120 tooth MINI-VELO"
- Thread starter LukeTheJoker
- Start date
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Luke has already posted the link... scroll back up to post #17 to find it... or just click here...
http://www.ratrodbikes.com/forum/index.php?threads/diy-slick-tires.64914/
Glen.
Thanks Glen!
Luke.
Luke.
Cool use for an otherwise trashed tire. The slick looks great. Even it it's thin, just don't be doing any skids!
Exactly right Pick! With these going on the racer build, using rim brakes, I doubt I will wear through them too quick...
Had to do a quick mock-up with the as yet unmodified frame just for laughs, those slicky tires look right at home and make the bike!
Really tempting to go buy a fat ramp/park BMX tire, like a 2.4" wide and slick it up for the back, but I wont, would go against the racer look...
Luke.
Todays update:
I was thinking last night that a chocolate brown bike with white slicks would look cool, so dug through my tire pile and dragged out 4 white tires, two did not pass muster due to cracks and the other two only barely scraped through as they were starting to craze, decided to try it anyway with the two crazed ones:
They look really good, but due to the crazing I had to sand more off than I would have liked, so they are thin and also due to the scuffing of the sanding they mark really easy, so I don't think they will go on the bike, they would be great for a wall hanger/display bike but just not practical for a daily rider which is what I hope this bike will end up being.
After doing some work around the house I started gathering parts ready for the frame chopping, a set of 20" racer style forks, stripped the donor frame, found a front chainring, chose some brakes etc.
After doing all that I realised I was starting to feel a bit sick, and realised just how hot it was in the sun, so now inside in the aircond and I think I am done for the day, shame because I wanted to modify the frame today as the next two day at least are fire ban days...
Luke.
I was thinking last night that a chocolate brown bike with white slicks would look cool, so dug through my tire pile and dragged out 4 white tires, two did not pass muster due to cracks and the other two only barely scraped through as they were starting to craze, decided to try it anyway with the two crazed ones:
They look really good, but due to the crazing I had to sand more off than I would have liked, so they are thin and also due to the scuffing of the sanding they mark really easy, so I don't think they will go on the bike, they would be great for a wall hanger/display bike but just not practical for a daily rider which is what I hope this bike will end up being.
After doing some work around the house I started gathering parts ready for the frame chopping, a set of 20" racer style forks, stripped the donor frame, found a front chainring, chose some brakes etc.
After doing all that I realised I was starting to feel a bit sick, and realised just how hot it was in the sun, so now inside in the aircond and I think I am done for the day, shame because I wanted to modify the frame today as the next two day at least are fire ban days...
Luke.
If you plan out your cuts and all that you should be able to knock it out quickly for the frame mod the next day you can weld. Take care until then and God bless.
Thanks guys!
Yeah I will have to take it slower on the build than I would like, unfortunately even at night on fire bay days you are not allowed to weld or grind, so I have till midnight tonight to do it, or have to wait till at least Monday 12:01 a.m.
That is life this time of year, and the reason I was not going to join the build-off, but glad I did, loving the way this will work out!
Luke.
Yeah I will have to take it slower on the build than I would like, unfortunately even at night on fire bay days you are not allowed to weld or grind, so I have till midnight tonight to do it, or have to wait till at least Monday 12:01 a.m.
That is life this time of year, and the reason I was not going to join the build-off, but glad I did, loving the way this will work out!
Luke.
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Love those tyres Luke, you could have used a carving knife rather
that go the sanding them back, you've put Burt Munro to shame!
that go the sanding them back, you've put Burt Munro to shame!
the white tires are cool looking!! can't wait to see more
Black tires for ridin' since them whites are so thin, they be just for posin'
Carl.
Carl.
If you use the white tires have bleach ready to clean up... LOL
I say go for the white tires even if they do get dirty fast.
I say go for the white tires even if they do get dirty fast.
Well after a bad fire day yesterday, (We actually had our bail-out gear ready and two fires got within 20 km (12 miles) of us) today is a good day and no fire bans, so started work on the bike, I was not working for long when I had an idea, ran into town with two rims to get the freewheel clusters removed:
The one on the right (14-28 tooth) is the original off the rim for the bike, the other (13-34 tooth "Mega Range") is off a Giant Elmore touring bike I picked up a while back.
I was planning on running the original 14-28 with a 55 tooth front sprocket, giving a top gear about the same as my road bike, but realised I would be pretty much never using the lower gears with the small 20" tires. So I started thing about what other sprockets I have, as part of my order from Jon @barnbikes I got two 70 tooth sweetheart sprockets, working out the ratios with them gave good results but the sweetheart did not suit the look of the bike one bit, I even considered cutting the webbing out and welding it to a normal sprocket...
Then I remembered the mega range freewheel, and quickly sat down and did some calculations, got the answer I wanted, and jumped on the computer to do a mock-up:
Ok, that looks doable...
You might be wondering where is he getting that huge front sprocket from and just how big is it? Well also as part of my order from Barnbikes I got two 120 tooth sprockets for use on an early speed record styled bike, but of course I have 2 and only need one for that...
So here it is, sitting on top of one of the 20" slicks for this bike:
A quick visit to the SheldonBrown gear inch and rollout pages gives these numbers:
One revolution rollout low gear: 218" (5.5 meters)
One revolution rollout high gear: 565" (14.5 meters)
Gear Inch ratio low gear: 70.58
Gear Inch ratio high gear: 184.61
Quote from the Sheldon Brown pages: The lowest gear on most mountain bikes is around 22-26 inches. The highest gear on road racing bikes is usually around 108-110 inches.
So it should provide a nice useable range for road biking in the first 2 gears or so, but the top ones would be for theoretical "drafting behind a car for a speed record" use only!
Also picked up some 100mm (4") PVC water pipe while I was out, got a use for it on this bike too...
Anyway, got to get out there and build it now!
Luke.
The one on the right (14-28 tooth) is the original off the rim for the bike, the other (13-34 tooth "Mega Range") is off a Giant Elmore touring bike I picked up a while back.
I was planning on running the original 14-28 with a 55 tooth front sprocket, giving a top gear about the same as my road bike, but realised I would be pretty much never using the lower gears with the small 20" tires. So I started thing about what other sprockets I have, as part of my order from Jon @barnbikes I got two 70 tooth sweetheart sprockets, working out the ratios with them gave good results but the sweetheart did not suit the look of the bike one bit, I even considered cutting the webbing out and welding it to a normal sprocket...
Then I remembered the mega range freewheel, and quickly sat down and did some calculations, got the answer I wanted, and jumped on the computer to do a mock-up:
Ok, that looks doable...
You might be wondering where is he getting that huge front sprocket from and just how big is it? Well also as part of my order from Barnbikes I got two 120 tooth sprockets for use on an early speed record styled bike, but of course I have 2 and only need one for that...
So here it is, sitting on top of one of the 20" slicks for this bike:
A quick visit to the SheldonBrown gear inch and rollout pages gives these numbers:
One revolution rollout low gear: 218" (5.5 meters)
One revolution rollout high gear: 565" (14.5 meters)
Gear Inch ratio low gear: 70.58
Gear Inch ratio high gear: 184.61
Quote from the Sheldon Brown pages: The lowest gear on most mountain bikes is around 22-26 inches. The highest gear on road racing bikes is usually around 108-110 inches.
So it should provide a nice useable range for road biking in the first 2 gears or so, but the top ones would be for theoretical "drafting behind a car for a speed record" use only!
Also picked up some 100mm (4") PVC water pipe while I was out, got a use for it on this bike too...
Anyway, got to get out there and build it now!
Luke.
On the bike mock up:
Got some stuff ready for welding and cutting, but it is just too hot in the sun, going to wait till evening to get into it.
Here is the sprocket jigged up ready for welding:
Anyone care to guess how this pile of stuff including ape hangers, a piece of 4" PVC water pipe and some pool fencing will end up as handlebars on the bike?
Luke.
Got some stuff ready for welding and cutting, but it is just too hot in the sun, going to wait till evening to get into it.
Here is the sprocket jigged up ready for welding:
Anyone care to guess how this pile of stuff including ape hangers, a piece of 4" PVC water pipe and some pool fencing will end up as handlebars on the bike?
Luke.
Productive evening, felt good getting stuff done for a change, just had to stop because the lack of light makes it kinda hard to see and I didn't feel like setting up the worklight...
So, got the sprocket welded up then started on the rear triangle of the frame, lots of working out gave me a drop measurement of 4.5" or 112.5mm, with that in mind I cut the seat stays just above the brake bridge to hold everything together and then cut the chain stays away from the bottom bracket, moved it down the required amount and welded it back to the BB, then bent the seat stays back forward so they were pointing at the right place, measured how long a gap there was and set out to cut some donor tubing. That is when I ran into issues...
The frame I am using has odd size tubing, I have lots of donor bikes with tube sizes both thicker and thinner than the ones on it, but no matches!
Ended up finding an old MTB with tapered stays and cutting them at the point they matched the thickness of the stays on the bike, then welded in a new brake bridge to hold everything in place, cut the stays on the bike to the same length as the donor stays and tacked it all up, the result ended up very nice, just was a lot of hassle and wasted some build time...
So here is the bike as it sits, mocked up at roughly the right height and angles:
Will have to remake the drive side chainstay yet to clear the sprocket but wanted everything lined up in place first.
Next up will be the front end, have to make a long headtube, extend the fork to match, probably take some of the bend out of the fork to get the geometry closer to a race bike and move the bottom frame tube down at the front to match the long headtube.
Looking forward to building the bars the most though, going to be a bit of a challenge and something I have never done before...
Luke.
So, got the sprocket welded up then started on the rear triangle of the frame, lots of working out gave me a drop measurement of 4.5" or 112.5mm, with that in mind I cut the seat stays just above the brake bridge to hold everything together and then cut the chain stays away from the bottom bracket, moved it down the required amount and welded it back to the BB, then bent the seat stays back forward so they were pointing at the right place, measured how long a gap there was and set out to cut some donor tubing. That is when I ran into issues...
The frame I am using has odd size tubing, I have lots of donor bikes with tube sizes both thicker and thinner than the ones on it, but no matches!
Ended up finding an old MTB with tapered stays and cutting them at the point they matched the thickness of the stays on the bike, then welded in a new brake bridge to hold everything in place, cut the stays on the bike to the same length as the donor stays and tacked it all up, the result ended up very nice, just was a lot of hassle and wasted some build time...
So here is the bike as it sits, mocked up at roughly the right height and angles:
Will have to remake the drive side chainstay yet to clear the sprocket but wanted everything lined up in place first.
Next up will be the front end, have to make a long headtube, extend the fork to match, probably take some of the bend out of the fork to get the geometry closer to a race bike and move the bottom frame tube down at the front to match the long headtube.
Looking forward to building the bars the most though, going to be a bit of a challenge and something I have never done before...
Luke.
How are you planning on mounting that sprocket? Are you going to use spacers to push it to the out side of the chain stay? Or cut the chain stay? If spacers then how are you going to align the rear hub to keep the chain lined up? If you're cutting the chain stays then how are you going to keep it structural?
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Questions that I have been working on for months for the other speed racer build!
The sprocket will get welded to a three piece crank arm that has been relieved of its riveted on sprocket, the chainstay will be what gets modified, I have some ideas on how I am going to do it, but nothing fixed in place yet, the main advantage I have is that it is mainly under tension, so I could even run some 4mm flatbar as a chainstay on that side if necessary, if that is what I end up doing I will brace the other side chainstay a bit to compensate for the loss in sideways strength.
Luke.
The sprocket will get welded to a three piece crank arm that has been relieved of its riveted on sprocket, the chainstay will be what gets modified, I have some ideas on how I am going to do it, but nothing fixed in place yet, the main advantage I have is that it is mainly under tension, so I could even run some 4mm flatbar as a chainstay on that side if necessary, if that is what I end up doing I will brace the other side chainstay a bit to compensate for the loss in sideways strength.
Luke.
Been looking quite a bit at that picture, and cant help thinking that maybe the 120 tooth sprocket is a bit too much on a 20" wheeled bike???
Took a pic with one of the 70 tooth sweetheart sprockets I have, which do you prefer?
Luke.
Took a pic with one of the 70 tooth sweetheart sprockets I have, which do you prefer?
Luke.
I'm torn. The 120 tooth brings the bike into the realm of the sick just like your fat tire builds. The 120 is also going to be a lot more challenging to make work. The sweetheart 70 tooth looks tame by comparison but it probably gives you pretty close to exactly the gearing you're looking for and looks nice and balanced on the bike.
The 120 is mind boggling, awesome and somewhat impractical, the 70 is refined and purposeful. Pick your aesthetic.
