banjo_mole 

Hello!

I'm on the prowl for a new bicycle frame. I ride a 50cm frame, and I wanted to have it made with a very light tubing.

I read... somewhere... (Where? I CANT FIND IT!) that a tubing manufacturer makes .6-.4-.6 tubing for the Japanese market and that it works well for a lighter, more flexible small frame. Kaisei? Ishiwata? I don't recall.

Is anyone familiar with a traditional diameter DB tubeset like this?

Thanks!

Andrew R Stewart 

Take care in your wishes. Traditional diameters and very thin walls make for a very flexible flayer. Great for climbing in a low effort and floating over ripples. but not so much for jamming and aggressive motions. Ishiwata (Kaisei) holds a special place in my riding. I built a frame from it's 022 set back in the late 1970s. While it served me well I "moved on" to lighter stuff. Ending up with Columbus KL (.5/.7). A great century bike in the classic sense but like Andy Hampsten said, the only thing worse the climbing with an ultra light bike was descending with one. (This is not an exact quote but the jist of it).

When all we knew was traditional diameter tubing we overlooked the ride quality shortcomings of these bikes. But these days we're smarter and have better options. For only a few onces more you can have a more solid frame. Really consider a step oversize diameters as the least. Andy.

unterhausen

some NOS Tange or NOS Ishiwata maybe? I would just go with one of your options in .7/.4/.7 and be happy it was less likely to break.

You are more likely to feel a difference if you use one of the traditional oval fork blades than if you actually manage to track down thinner butts. Both True Temper and Kaisei (from UBI) offer .7/.4/.7 Maybe spring for the S3 stays.

I liked working with the Columbus SL tubes I put together a few years ago. I suspect you couldn't tell that it was just a little thicker.

It's most important that you find someone that is sympathetic to your wishes. I'm with Andy for the most part, I think oversize tubing is better.

reddog3

By "traditional size" I assume you mean 1" TT- 1 1/8 DT? There's probably a good reason that really thin wall tubes are hard to come by in these sizes. You didn't really state whether it is the "comfort" of a flexy flyer, or a lighter weight frame you seek. Or is it just the appearance of the smaller tubes? I'm with the others here and suggest larger tubes. Of course it depends on the purpose of this bike.

Personally I prefer a "stiff" frame. As Andy mentioned there's nothing more unnerving than a hard descent on a noodle. There are other ways to build compliance and comfort into a frame rather than resort to small diameter lightweight tubes. If the purpose is a leisurely jaunt on the MUP- do whatever you want.

Building small lightweight frames has it's challenges. I know- I'm one of those short guys and I suppose my frame size is what would traditionally be classified as 48-49cm. You'd think that a smaller frame is lighter. Not necessarily so. It's the tube selection and availability that messes the whole thing up. Generally the thinner wall, larger diameter (lighter weight) tubes don't have adequate butt lengths to be used in smaller frames. So... I accept the fact and live with a few more grams.

If light weight is your goal, get there with component selection. A steel frame is gonna weigh what it's gonna weigh. I have a tough time doing a steel frame in my size at much less than 1500g, unless I sacrifice on what I consider to be good joinery and design. I can do bigger frames lighter than the little ones. At 1500 gram frame weight one can still build a 13# bike.

Doug Fattic 

I'm actually on the other side of this discussion with my buddy Andrew. I built a 56 cm frame out of 6/3/6 Ishiwata 015 (1" top tube) back in the late 70's. The whole bike weighed just over 15 pounds. I expected it to be very flexible like everyone said it would be but it worked perfectly for me even when i was going flat out. Some others racers didn't like it when they tried it but then they were sprinting up hills. Later I made another frame for myself with a 6/3/6 down tube and a 7/4/7 top tube. Loved the ride of it too but the problem with 6/3 is that it isn't robust enough for routine riding. It was not too flexible for me. The Europeans pros used it only for special events. I hit a small pot hole on a training ride (when the wheel I was following didn't point it out) and not only did it put a dent in my front rim but also put I crimp in my down tube. I replaced it with a 7/4/7 and still love the way it rides. At the time I was 5'8" and weighed around 130 lbs. I could hang with the cat 2s and 3s back then as long as I never had to take a pull at the front. So there was always sprints out of the corners and hills to climb at speed.


Tubing diameter/gauge choice has something to do with pedaling smoothness too. I used to put more powerful riders than me on the back of my tandem when we went on those training rides and with some I could barely keep it going straight and others it was a smooth as silk ride.


So by all means use a 1" top tube with at least 7/4/7 unless you are a sprinter type. An alternative might be to use a 6/3/6 top tube. Reynolds used to make them and might still have some in inventory. I wouldn't use a 6/3 down tube just because of durability. Light tubes do take more skill to braze however. I don't allow my framebuilding class students to use light tubing for that reason.


7/4/7 OS tubes don't work nearly as nicely for me at all. If you do the numbers, they are the equivalent of 9/6 in standard tubing which is way overkill for me. I don't like the ride of either bigger diameter tubes or heavier gauges nearly as well. This is a Catholic/Protestant, Democrat/Republican argument that will never have a consensus. What I know is that I personally greatly prefer the ride of light gauged standard diameter tubing (and I've made and personally ridden almost all options). Jan Heine writes a lot about the classic French builders Rene Herse and Alex Singer that used super light tubing and why he loves the ride of those bikes. He gets a lot of grief for his hypothesis of why it works (and I don't agree with that guess) but speculating on reasons doesn't change a rider's preference. Actually there aren't many people that have actually tried riding a frame made out of light standard tubing because production makers don't use it.

squirtdad

just of of curiosity....what would the weight difference be for a 50 cm frame between the listed super light stuff and 'normal" tubes?

JohnDThompson 

Kasei took over Ishiwata's production equipment and their tube set line-up closely follows that of Ishiwata:

https://www.bikeschool.com/PDF_Files/kaisei.pdf

The "017" set is closest to what you proposed, with 0.7/0.4 walls.

As Doug noted, this can give a quite satisfactory frame, but not as robust as a thicker tube set. The lighter the rider, the better suited to a light weight tube set.

unterhausen

the difference in weight between .6mm butts and .7mm butts can't be much. And I'm thinking that a 50 cm frame is going to have a significant portion of the butts cut away. In any event, I can't imagine there will be a discernible difference in stiffness between those tubes. Although I've always been a masher, not a spinner. I went from a standard Columbus SL frame (9/6/9) from back in the day to Spirit for Lugs OS tubing (7/4/7), and I have to say I can't tell the difference. So maybe I'm not the person to ask.

For some reason I have a 7/6/7 tube that I forget buying. I was looking at it, and I thought it was straight gauge. You can barely see the butts, and my butt measurement tool isn't quite stiff enough to measure them.