Tuesday, November 30, 2010
Friday, November 26, 2010
Standard tubes
Most commercial tubes are put together with a 180/90 degree layup which is really strong against bending forces, decent against crushing, but isn't designed to specifically deal with the twisting forces often found in bikes. The down-tube in partciular has a twist-resist function as well as it's bending resistance.
Experimenting
Looking to try some different layups with this latest batch of carbon from Enve Composites. Carl at Enve laid up a goodly set of 45 degree cross ply tubes and I'm going to use those in my next project: a road bike for my teammate Jerry. You can see that the fibers run differently from the previous picture.
Daruma Cross Evaluation
The beta-testing phase of Daruma Cross has been pretty good. Overall, I like the bike much more than my previous too-small cyclocross frame. I think that this hits a bit closer to the mark for "excellent cross bike" than does my road bike. The bike is extremely stable, especially at speed. I'll be looking for a slightly shorter fork to hopefully make things a bit quicker at slow speeds. Ride quality is what I've come to expect from bamboo: silky. I know that low-pressure tires make a huge difference, but even with my Maxxis Mimo's pumped to 55 psi, the bike rides smoothly over road bumps and even turf. I've also decided that I must have done some things right, because I've never been quite so easily able to land every one of my running remounts. I'm also pleased that there has been zero complaint from the seatpost/mast area either. I believe stiffness to be good, though I occasionally do hear some rear brake rub. That could be partly due to flexing wheels, but it's hard to say until I switch those out for something that is known to be super stiff. I'm willing to concede a bit of stiffness for the ride quality though, it's nice not to be pitched all over creation.
Each one of the bikes that I've made for myself could be better in some ways though. I guess it really boils down to needing to get better at bike frame design. When building bikes for myself, I tend to follow my standard recipe technique: look for all of the things that I think are cool, try to slap them all together, and then throw a bit of experimentation in for good measure. Ask anyone that's tried my cooking.
In both of these bikes, I made some really long top-tubes to help accomodate for my preferred mid-foot cleat position. In the case of my road bike, I was pretty much spot-on with the length, but a slight miscalculation in which forks were available to me, left me with a steeper-than-desired headtube. It gets a little quick steering, though still within reason, until you're going at speed. My other miscalculation has more to do with a lack of understanding of the inherent flexibility of bamboo. I got all artsy with the seat stays and picked some nicely re-curving sections, but at the end of the day, I really probably should have gone with some stouter bits to boost the rear-end stiffness a bit.
As far as my quibbles with the D-Cross, it seems that I could have made the top tube about a centimeter shorter, and probably could have done something similar to the chainstays. My design goal was really to make something that would absolutely not have any toe overlap, and given my big hooves and mid-foot cleats, this required some extra length in the front end. I was prepared to run a shorter stem as a result, and I suppose that a 100mm stem is not really short, but I think that I could have easily gotten away with the shorter overall length. I think the next couple of bikes I do will be a bit more stock geometry, so that will help me get my design mojo going a bit: being able to tweak a known quantity is probably a better way to learn than winging it repeatedly.
Dimensions for Daruma Cross:
HTA: 72 deg, should have gone to 72.5 with the fork that I'm currently using. Will look to change that once I can afford a new one.
STA: 73 deg, but who knows with the curvy seat tube that I ended up using. Seems more like a 74 or 75 up towards the top. Fits perfectly though.
BB Drop: 70mm
ST: Virtual 590mm
HT: 180mm
TT: 605mm
CS: 425mm
Each one of the bikes that I've made for myself could be better in some ways though. I guess it really boils down to needing to get better at bike frame design. When building bikes for myself, I tend to follow my standard recipe technique: look for all of the things that I think are cool, try to slap them all together, and then throw a bit of experimentation in for good measure. Ask anyone that's tried my cooking.
In both of these bikes, I made some really long top-tubes to help accomodate for my preferred mid-foot cleat position. In the case of my road bike, I was pretty much spot-on with the length, but a slight miscalculation in which forks were available to me, left me with a steeper-than-desired headtube. It gets a little quick steering, though still within reason, until you're going at speed. My other miscalculation has more to do with a lack of understanding of the inherent flexibility of bamboo. I got all artsy with the seat stays and picked some nicely re-curving sections, but at the end of the day, I really probably should have gone with some stouter bits to boost the rear-end stiffness a bit.
As far as my quibbles with the D-Cross, it seems that I could have made the top tube about a centimeter shorter, and probably could have done something similar to the chainstays. My design goal was really to make something that would absolutely not have any toe overlap, and given my big hooves and mid-foot cleats, this required some extra length in the front end. I was prepared to run a shorter stem as a result, and I suppose that a 100mm stem is not really short, but I think that I could have easily gotten away with the shorter overall length. I think the next couple of bikes I do will be a bit more stock geometry, so that will help me get my design mojo going a bit: being able to tweak a known quantity is probably a better way to learn than winging it repeatedly.
Dimensions for Daruma Cross:
HTA: 72 deg, should have gone to 72.5 with the fork that I'm currently using. Will look to change that once I can afford a new one.
STA: 73 deg, but who knows with the curvy seat tube that I ended up using. Seems more like a 74 or 75 up towards the top. Fits perfectly though.
BB Drop: 70mm
ST: Virtual 590mm
HT: 180mm
TT: 605mm
CS: 425mm
Friday, November 19, 2010
This just in...
Bigfoot was spotted riding his cyclocross bicycle at Belmont Plateau in Philadelphia yesterday evening at approximately 7:30 last night. No clear footage was available, but we got this grainy photograph to prove that he was there. Enjoying himself immensely.
Daruma Cross emerges from the shadows
Ok, Ridiculous to take photos of one's bike at night. But I couldn't resist.
Tuesday, November 16, 2010
Monday, November 15, 2010
Frankencross
I cobbled together the cross frame into a bike on Saturday to give it a test run around the 'hood and to see if there were any tweaks that I needed to make before spending hours and hours sanding and painting.
Turns out, as to be expected, there were. Firstly, I'll say that the bike rides pretty well. It fits nicely, and has cured the dreaded toe overlap issue that plagued my other cross bike. Big feet plus wacky cleat=problems with toes getting rubbed off.
The second thing I noticed was the lack of rear brake stiffness. On the SuperCommuter that I built for Dave a year or so ago, I wrapped the heck out of the seatstays around the brake bosses in an effort to keep things really sturdy. It worked really well there, and with the through-the-tube brake cable, made for some really top-notch brake action. With this bike, I had some issues with flex after my much lighter layup schedule on the seatstays. The braking was a bit on the mushy/ineffective side for my liking, so I ended up taking off the brakes and putting another 3 or 4 layers of unidirectional stuff in both spiral and longitudinal patterns around the stays. I am going to finish putting it together tonight, but overall I'm liking how things are looking at this moment.
I'll put up some pictures after I de-weirdify it a little more.
Turns out, as to be expected, there were. Firstly, I'll say that the bike rides pretty well. It fits nicely, and has cured the dreaded toe overlap issue that plagued my other cross bike. Big feet plus wacky cleat=problems with toes getting rubbed off.
The second thing I noticed was the lack of rear brake stiffness. On the SuperCommuter that I built for Dave a year or so ago, I wrapped the heck out of the seatstays around the brake bosses in an effort to keep things really sturdy. It worked really well there, and with the through-the-tube brake cable, made for some really top-notch brake action. With this bike, I had some issues with flex after my much lighter layup schedule on the seatstays. The braking was a bit on the mushy/ineffective side for my liking, so I ended up taking off the brakes and putting another 3 or 4 layers of unidirectional stuff in both spiral and longitudinal patterns around the stays. I am going to finish putting it together tonight, but overall I'm liking how things are looking at this moment.
I'll put up some pictures after I de-weirdify it a little more.
Wednesday, November 10, 2010
Brakes
Brakes, straight out of the bag. Much finishing to be done yet, but things are getting there. I've done a lot of sanding since this time, but it is still looking a little rough. More sanding is in order.
Philly Bike Expo
So I let Mike from Trophy Bikes talk me in to bringing my bike to the Philly Bike Expo on the 30th and 31st of October. Overall the show was a great success, lots of good exhibitors from the Philly area and elsewhere, and lots of cool bike stuff to look at. The best part about bringing my bike there, was that I got a ton of props for it. The worst part about bringing my bike there is that now all I want to do is be a framebuilder. Ugh. If I didn't have such a large amount of money invested in my education (and the loans to show for it) I'd be doing bikes full time.
I love these sorts of shows because they're full of people who make things, and those who love the excellent products. I had a good chat with a guy from Houston named Tim Massengill, who makes some really nice looking frames from steel, and to my excitement, some equally cool ones out of carbon fiber. Check his stuff out here.
Budd Bikeworks
One of the most interesting guys there was the dude from Budd Bikeworks with a couple of his steeds. While he works exclusively in steel, I like the design philosophy of "make it and see how it turns out" Check out the website here: http://www.buddbikes.com/
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