5 Aug 2007

     As I got back from a trip rather late in the day, I only managed about 4 hours worth of work, but managed to salvage, fill holes and clean up a headtube, plus chop and shorten an old brazed road bike fork down to better fit a 451 front wheel.  I also decided to be clever, and make an offset fork so that I would hopefully be able to skip the part about heating and bending the fork legs to get the chain to clear properly.  To the right are the fork parts in my new (not painted yet) fork jig.

     To the right is the finished set of forks with a 451 in them.  You can see than a normally trued wheel is up against the left fork leg and all I have to do is true the wheel back to the right and center it under the brake caliper mounting hole,and I'll be good to go.  This isn't the wheel I'm planning to use, I need to build a 32 hole AL wheel for it yet.  It has about ½" of clearance between the bottom of the crown and the top of the Stelvio.  Below is a shot of a 20" (406) AL rim in the same set of forks.  Again, all that has to happen is to true the wheel to the right, and we're golden.  Also, once a tire is on and I know what the exact tire height is with a 20" Stelvio on the rim, it looks like I can chop another few inches off the fork legs.  This is easily accomplished in the jig by simply sliding the steerer tube towards the axle mount.

6 Aug 2007

     Today I had a little more time available and got all the main frame pieces cut out, test fitted and layed out for a quick eyeball.  It looked pretty much as per the plan, so I took a wire wheel to them to clean them up, deburred the insides again in case I decide to go with internal cables again (likely) and started tacking them together.

     Here's the rolling frame with a 52/39 double chainring set.  I'll be cutting them down to 140mm and will gusset the same top and bottom angles as I did with the '74.  The wheelbase is ~44" so far, I think and I'll take final measurements after full welding has been done.  It took about 4 hours of work yesterday to get the parts salvaged and ready, and only about 3 hours to cut the squre stock, and get the bike to the current level of completion.  I also built a new 32 hole 451 front wheel for the '74, and need to make another for the '44.

     Next up is finish welding, add the two gussets, add the chain idler and the FD post.  That should pretty much take up tomorrow night.

8 Aug 2007

     Last night was spent doing wheels.  I took the 451 I just built, trued it up, dished it for the front end of the '74, switched the Stelvio over to it, and the Raptor 74 is good to go.  I took another 451 wheel and 32 hole hub and laced up a heavily dished wheel for the front end of the '44 and its offset fork.  I had to custom cut and thread the spokes, so that pretty much took care of last night.  I laced it up in a 2 leading/2 traqiling pattern because the standard old "3 cross" is pretty boring.  This wheel should be morethan strong enough for the front end of these little bents.  I used the same pattern on the front wheel for the '74 too.  

     To the right, you can see the amount the front wheel is dished and it looks like the fork leg doesn't need to be touched at all this time.  I'll know for sure though when it comes time to run the chain, which should be tomorrow night.  In the picture, the wheel doesn't look as dished as it does in real life - likely due to the sub-standard photography work.

     Below that, is the frame so far.  I put in a lot of work to drill the seat mount holes, finish weld the joints, clean them up, and cut and install the gussets, yet it looks little different than the picture from 2 days ago. :(  After measuring the head tube angle after all the finish welding and gussets, the angle is 71º instead of the planned for 73º.  I wonder how much of a noticeable difference that will produce in the handling?  At the very least, it will be easier to ride at low speeds.  Tomorrow, I guess I'll finish up the seat mouts at the front and that way I'll have a better idea of where to mount the chain idler.  The chain should be higher up the forks too, due to the higher ground clearance, and that means the chain will clear the forks easier as well.  After the front of the seat is mounted, then I can run the chain, then do the rear seat supportsand weld on the rear derailleur mount.

11 Aug 2007

     I had pretty good focus today and am pretty happy with the progress made this afternoon and evening.  I welded on the rear derailleur mounting tab, and got the front seat tabs on so the seat could be test mounted and make sure that the chain would clear the front of the seat, which it does.  Originally, I had the chain run pretty much the same as the Raptor 74, but then I remembered a conversation with a guy who might be interested in it, and he was planning to do some touring.  Being loaded up with gear and having limited steering like the '74, is probably not a confidence inspiring combination.  So, I had to back-track a bit and see if I could cleanly get as much of the chain as possible out of the way of the front wheel.

     I started by moving the power side idler back to about 18½" from the rear axle.  This raises the power side of the chain higher up the fork leg, which increases the clearance, and it is easier to have the power side chain clear the right side chainstay when it's on the 30T cog at the rear.  The small amount of power side overlap on the front tire is minimal and allows more than twice the steering deflection than the '74.  I used two RD pulleys to route the return side of the chain in close to the frame, inside of the power side, and over the front wheel.  I got the top idler pulley high enough so that the chain clears the front tire even with a 60T ring on it, and if the chain does hit the tire, it slides off the top of it instead of hitting the tire side.  Both pulleys have small U-shaped chain keepers, that are 3/8" wide x .049" thick, that I made out of a piece of square tube hammered flat.  It might add a little more drag, but the top pulley has a ceramic bushing and with both pulleys fully lubricated, the drag should be minimized.  It doesn't feel bad at all right now.  The chainline is a little more convoluted than what I had envisioned for this bent, but the form needs to follow the function.

     Tomorrow, the plan is to make the rear seat stays, install the seat mesh, and install the brake calipers.  I also need to weld handlebar ends onto the EMT bullhorn bars so normal bike controls will fit properly.

14 Aug 2007

     Been busy over the last few days so didn't get as much accomplished as planned - usually always the case.  However, yesterday I did manage to fabricate and install the upper seat tabs, the rear seat support tubes and their tabs and get them welded on.  The seat tubes are 5/8" x .035" Al tubes and the seat is set at about a 35º angle for starters.  Laid back enough for pretty good aero, should be able to avoid recumbent butt, and the power production should be good as well.  I got the seat mesh squared away, dyed the nylon cord, bought a few more ¼" Al rods and drilled out the seat mounting holes to match the skewer.

     Tonight, I installed the mesh becuase the nylon cord had all day to dry out.  I think on the next seats, I'll punch the cord holes in the mesh seat every 3 " instead of every 2".  There should be no strength issues and it'll use less cord.  I also cleaned up the beads for the three idler tabs I welded on yesterday.  I took a piece of .049" thick tubing and sliced a 3/8" section off it.  Hammered it flat, then bent it around a piece of tubing to make the chain keepers for the return side's idler pulleys.  The both pulleys are recycled from a friend who replaced them on his triathlon bike, and the top idler even has ceramic bushings in it.  Hi-tech or what!? :)  There's a little bit of slack in the chain yet when you back pedal, but that's because I left it a little long as I plan to change the rings out to maybe a 58/48/38 oval set - or something along those tooth counts.  I haven't quite decided yet so I need to sit down with my GI calculator and see what I think is a suitable high/low gear combination.  There was a little bit of resonance in the bike frame when back pedalling after I had the idler tabs tacked on, but that went away after I finished welding the tabs.  With the seat all the way back (I still have room for maybe 2" more of rear adjustment) it's still a little short for me compared to the '74 but that was the plan, and I should have more than the original 6" of seat movement I planned for.  With the 175mm cranks, and the seat being close, I couldn't really get properly set up to ride it, but I have a tall stem with a good 4" extension, so it was still rideable bow-legged style.

     The test ride went very well considering I didn't bother to add a shifter and brakes yet.  The seat definitely feels higher (which it is), it corners very smoothly and easily most likely due to the more relaxed head tube angle, and higher seat postion, but also because the chain does not limit the front wheel deflection.  With the seat stays mounted to the top of the forks, it feels a fair bit stiffer than the '74, which was also my plan.  I need to shorten the cranks so I can get the cockpit set up properly with the final pedal length.  Fine tuning the bar position and angles is pretty much useless without the final proper pedal length.  I think the wheels need to be trued over to the right about another 1/8" to 3/16" and it'll feel even better.  I'm very happy with the little 44 and it should roll as well as it's big brother, especially once I can get some good Stelvios on it instead of the 65 psi Maxxis hybrid tires.

     So, crank shortening first, a couple more seat holes, and then we can work on the bar position.

23 Aug 2007

     I took the '44 and had some shorter riders test it out to give me some assessments of it.  They liked it but they didn't like the fact that the cranks were too close to the tire and could hit it and jam. I particularly didn't like that either, so I put it on my list of changes. I modded the booom by notching it and bending it upwards to give the boom a total distance of 16½" from front axle to BB axle.  I don't know why I didn't do this in the first place.  Learning from my lesson, that's exactly what I did with the '44i to make sure I didn't have to do the same mod to it later.  I got the cranks shortened and the front derailleur post installed, and then I had to wait for some parts to come in before I could go any further.  I took the bent back to the guys to test ride again, and they were very happy with it.  Happy with the handling, the comfort of the seat and the fact that there was no crank - tire problems anymore.  The boom adjustment also raised the power side of the chain a bit and the tire can be turned even further with only minor tire contact and only at extreme steering deflection.  I also got the front derailleur cable guide and stop mounted, as well as both brake mounts.  All that remains for a full mock-up is to add 7/8" bar ends to the 1" handlebars, drill the holes for the internal cable routing, and then the whole thing can be assembled with the new parts.  No pictures though as it is all in bits and pieces right now :)

24 Aug 2007

     The '44 is all done now except for a couple small tweaks, like cleaning up the beads on the rear brake mount and lacing up a 9 speed hub into a 32 hole 451 rim so it can take a 9 speed cassette.  You can see the slight bend in the boom now so the cranks clear the tire.  The handle bar ends went on fine, but I think I'll go out and buy 10' of 7/8" x 1/16" steel tube if I can find it so I make make bullhorns without having to add the proper size bar ends at the end.  The shifter cables are run through the bars and emerge again near the stem.  The rear derailler goes back through the frame to the rear while the front cable stays external after that.  The brake cables were intended to run through the bars too, but it would be too many kinks in the housing and would have caused a lot of drag on the brakes for nothing more than cosmetics, so I didn't run the cables inside the bars.  The rear brake cable goes inside the frame though and comes out the top of the frame near the rear brake caliper.  It's got some Wellgo SPD pedals, Diacompe bar end shifters and nice, tight, stubby Tektro brake levers which provide ample leverage for the braking.  No real surprise, but this thing ended up at about 32lbs as well.

     Tomorrow it's going out for an extended test run, if it stops raining, by a new bent enthusiast just to make sure there are no last minute glitches.

8 Oct 2007

     Lots of life details keeping me pretty busy, but slow and sure, I'm gradually making some headway.  My friend had the '44 out for a good 40km test ride back in August and he really enjoyed himself.   While it might have looked a little rough in its unfinished state, and while the tires weren't optimum, the rider gave it a thumbs up, so it was time to finish it.

     I finally got it torn down and when I went to use one of the local powder shops, the one I had in mind had apparently gone out of business.  Too bad.  So, I spray bombed it with a combination of gloss and flat black.  I think it looks good with the blue cable housings and I also swapped out the yellow seat cover for a black one, which I think looks much better.  I also got a hold of some nice, smooth, high pressure IRC 451s so it should roll a whole lot better as well.  After that, it goes back out for a maiden test ride to fine tune things like seat and handlebar position.  I don't like letting my babies out without me doing the final debugging but the '44 is too small for me to ride, so I have to get my friend to give it the maiden run.

15 Oct 2007

     So, it rolls along nicely, but the RD pulleys on the reurn side of the chain were sending some vibrations into the frame and making too much noise for both of our liking.  Also, the water bottles my friend was using were so tall the top was touching the back of the seat. ??  So, first, I made some new pulleys useing roller blade wheels in the hipe that them being soft would absorb the vibration from the chain rolling over them. And they did.  I was also prepared to make some small extensions for the top bolts of the bidons so they could be tipped back a little to give more clearance.  Turns out, his -cough-legs-aren't-as-long-as-he-thought-cough-, so once the seat was moved forward a hole, the bottles fit fine.  The last ride was the ticket, and everything is good to go.  Later on this week, I'm going to take a rear rack and maybe a fender and mod it so it fits the bike and then it can get some saddle bag testing.

     After a little more time to get used to the bent, a couple more things will be on the list of final mods:

• drop a 9 speed hub and cassette on the rear wheel
• get a new set of cranks, cut them down to 140mm, and drop a triple on it so we can increase the high range

     More on that later though :)

1 May 2008

     A little more time turned into a lot more time, but the '44 is finally done.  The simplest of the mods was building up the new 9 speed rear hub and mounting up the new chain.  The next easiest was shortening the MTB cranks to 145mm and then making and tweaking the set of triple oval chainrings.  They're a 59/48/32 triple with 10% ovality and they are retarded 5%.  More info on them is here.

     One of the other mods was to install a MTB fender for the front wheel on the downtube.  Turns out the fender is too thick and there isn't enough space between the frame and tire so a thinner road fender would likely need to be tried instead.  Another mod was to make a rack on either side of the backbone, underneath the seat, to hold a small tent and an air mattress for camping while touring.  While this initially seemed like a fairly easy task, the rolls were bigger than anticipated and the tent was also heavier than anticipated.  Also, the size of the rolls made location of the rack on the right side problematic because the frame now has to be lower and interferes with the chain locations.  To work around the size, weight and chain interference issues the rack would need to be much bigger than anticipated, it would need to be heavier and stronger and it would mean breaking the chain to mount and remove the rack.  The biggest problem in my mind was the weight of the finished rack which I think makes it unacceptable.  In the end, it might be (or will have to be) just as easy to mount the rolls on the rack with the saddle bags.

     The end result is pictured on the right though and the main aims of improving the gear range at the top and bottom as well as providing a cargo capacity has been met.  Once the saddle bags are mounted, the only thing to finish up is to locate the safety flag so it is out of the way.