To fix or not to fix..

[Sheets of Easter]

I'm glad I found this group, because I need to figure out if a bike I obtained is worth saving. Perhaps you can help a cycling noob.

The other day my wife found a mountain bike that my neighbor left out for the garbage man. It runs and looks to be in decent shape, though it does have a lot of rust (including the brake calipers, which are completely rusted). After a bit of air in the tires, the thing rode well, but like I said, still needs work in terms of rust (especially the brakes). I think it would also use a paint job, and I'd like to add road tires so I can use it for running errands (I don't plan on offraoding that much).

Anyway, the bike is a Magna Excitor. I discovered from my research that it is a cheapo bike, and I don't think I've found anything positive on the web about it. I know that anything free is good, but is it worth my time and money to whip this thing into shape? Thanks

[happyslug]

1. From what I see it is an aluminum frame bike

Bikes frames are made of six different materials. The stiffer the frame, the easier it is to peddle. The following is from the least stiff to most stiff frame:

1. High Tension steel, the wonder material of 1900. Had the Titanic been made of High Tension steel, the Titanic would have survived the Ice Berg do to the flexibility of High Tension Steel. The down side of this flexibility is that while High Tension steel bike frames are easy to repair, they absorb a good it of peddling power do to its flexibility. Most cheap bikes are made of High Tension Steel.

2. Chrome molybdenum (Often called Chrome-Moly or Cr-Mo) is a much stiffer steel frame material. Often called the wonder material of the 1930s. Not as easy to repair as High Tension Steel, but a lot easier to peddle do to its much stiffer frame. High Tech bikes of the 1930s till today are made of this material.

3. Aluminum. This was the wonder material of the 1980s when Cannondale solved the problem of how to repair an Aluminum frame if the area where the rear wheel attached to the frame breaks. Prior to Cannondale, if that part went you have to junk the whole frame. Cannondale discovered a way to make that part removable from the rest of the frame, so if it broke, all that was needed is to pull the old part out and put in a new part. The part is kept with rest of the frame by very tights tolerances. Aluminum is even stiffer then Chrome-Moly so is even easier to peddle. Aluminum has greater strength at the same mass as steel, but at the same mass has much greater volume, thus Aluminum frame bikes tend to have thicker frame parts then other materials. Like Chrome-Moly Steel frame still a very good frame material, the following frame materials are all much more expensive for only a marginal improvement in frame stiffness (Remember Stiffer the Frame the easier it is to peddle the bike).

4. Magnesium. Not used much today, has a brief time in the 1980s. Stiffer and thiner then Aluminum, its one great fault was you could catch it on fire in an accident (and the Fire would be a Metal Fire, all it needed as Oxygen to burn, till the whole frame was gone). Magnesium is still used for certain parts but NOT parts that can be subject to a lot of heat if dragged along the road bed.

5. Titanium, the wonder material of the 1990s. Even lighter then Magnesium. thiner then steel, lighter then aluminum or Magnesium, with a temperature rating equal to steel (Almost impossible to catch of fire). Also 3-4 times the price of Aluminum, but its stiffness is NOT 3-4 times that of Aluminum. Most Titanium frames were made in China as titanium became cheap when the Russians stop building high speed jets that needed Titanium. Now not as cheap as it was in the 1990s and even rarer today then it was in the 1990s.

6. Carbon. This is the wonder material of today. As expensive as Titanium but can be molded into any frame since it is NOT a metal but a resin. Mostly seen on high end bikes bought by people who what the stiffest frame they can get. I do not believe it is cost effective for most people but if you want the little edge over other bike it is the frame to get (starting at $2000 just for the frame).

Given the above the bike you look at appears to be Aluminum, if that is true it is a decent bike. My only problem is the rear suspension. Such Suspensions are popular among off road racers for they permit the bike drive wheel to stay in contact with the ground more then a "Hard Tail" bike. My problem the rear suspension tends to undo the stiffness you get from a solid frame bike of the same material.

My point is the frame is decent and thus I would look into keeping it. The components are probably junk and needs to be replaced. Improve components would make the bike easier to peddle (I recommend getting Shimano XT components, Shimano's XTR are like Carbon Frame bikes, XTR components cost twice as much as XT parts, but are NOT twice as Good. XTR are designed for that person who wants an edge no matter the price. Thus unless you are Racer of bicycles, XT parts are good enough (I would also look into SRAM Parts, generally as good if not better then Shimano parts).

One comment on Shimano parts. Shimano sells various levels of bike parts, from racing quality down to some of th worse junk you ever saw. LX parts are not bad, XT are the most cost effective, XTR over priced for marginal gain (Yes I recommend XT parts more then the higher or lower price parts). I do NOT know what parts your bikes has, but I suspect some Shimano junk. Look into getting new wheels and drive train (and other parts) and if you are unwilling to do that, the bike is NOT worth keeping no matter how good the frame is.

[Sheets of Easter]

2. Wow. That's a lot of good info.

Thank you.

Truth be told, I really want a cruiser-style bike to match the one my wife bought off of craigslist yesterday. Mountian bikes aren't really my style. I figured maybe I could convert it to a road bike, but if costs more to swap it out one piece at a time, it may not be worth it.

:hi:

[happyslug]

3. Get want you want, you will like it better.

I tell people that studies have shown (and marketers count on) people will buy what they want more then what they need. Automobiles are the classic case, a person who lives on a country unpaved and unmaintained road, but who wants a sports car, will be happier with a Corvette then a four wheel drive SUV, even if he or she really needs a four wheel drive. The SUV craze was driven by people wanting something that will go off-road and in any kind of weather, even if they live on roads that are salted and cleaned every day.

The bike you find may be a good beater, something to fix up now just to bike but save your money for a better bike, one that is more what you want. I would get a bike frame that you want, even if you have to go cheap on the components (The Components can be replaced later, upgrading the bike as you replace parts). Remember the frame is the key and the most expensive part of any bike, get the frame you want, the best frame you can.

For example my present bike is a Cannondale Hard Tail. I replaced the front suspension front fork with a non-suspension front fork. I replaced the parts that came with the bike with XT and XTR parts (I over-spent on the XTR parts). I did this to make the bike lighter and easier to switch gears (I live in the Mountains of Pennsylvania where switching gears has to be down quickly). I recommend you get the best frame you can. I rarely go off road so suspension I do not need so I replaced the suspension with old fashion non-suspension parts.

Look at what you want and get it, you will like it more then if you go cheap.

[keith the dem]

4. Happyslug nails it

Fixing up an old used bike is much like fixing up an old used computer. If you know what you are doing and have a source for compatible parts, it can work. Most times, if you look at the cost of decent components, and the time involved in getting the stuff to work correctly, a mid range new bike looks like an incredible bargain.

P.S. Happyslug, did you get to see the Tour of PA as it passed through your extremely hilly neck of the woods?

[happyslug]

5. As to the Tour of Pennsylvania, I missed it, I was on Vacation in seeing the Kinzu Dam

n/t

[keith the dem]

8. Hopefully we'll have it again next year.

It was a blast being a part of that big traveling circus. I drive the medical car in the caravan behind the riders. John Kerry rode in the Z-team car for one of the stages.

I've really enjoyed your posts and pictures from western PA. THANKS

[wtmusic]

6. happyslug, WADR your stiffness ranking is almost exactly backwards

Based on elastic modulus, from stiffest to least:

Steel (most varieties similar, incl CrMo)
Titanium
Aluminum
Carbon

I've owned bikes of all these materials except Ti over the years, and carbon's appeal comes from it's lightness. Whether it's easy to pedal the bike or not depends on how hard you pedal. If you're a recreational cyclist and the frame is well made you will see very little difference in perceived effort based on frame material.

More info on stiffness:
http://www.sheldonbrown.com/frame-materials.html#stiffness

[keith the dem]

7. I've also had all but a Ti.

Being 50 years old and a little over my ideal weight, I've found the big advantage of a carbon frame is not the weight, but the ride. It is very stiff in the ability to get the power from the pedals to the wheels, but very resilient with bumps and potholes. Holes that would give you a good jarring on the steel or the aluminum frames (let's not even talk about the first generation Cannondale I had) give only a nice thump on the carbon frame.

[wtmusic]

9. Carbon is great

I'm also 50 and agree completely about the ride. I ride 100+ miles/week and carbon's just more comfortable to ride long distances on.

The whole concept of stiffness is a little misleading, in that the geometry and thickness of the frame have more to do with it than material. The comfort factor of carbon, IMO, mainly comes from reduced vibration. Most composite materials have good vibration-damping qualities and carbon fiber/resin is no exception.

I noticed Sheldon Brown's page on stiffness is outdated -- in 2008 carbon is a fully mature technology. I'd be surprised if anyone in this years Tour is riding anything else.

[keith the dem]

10. All the pro teams use Carbon

I was behind a big pile-up in a training race a couple of weeks ago, The whole sound of carbon bikes crashing is so different from the clang of metal bikes crashing. It's sounds more like the sound of football lines clashing instead of what I remember. Either way it's a terrible sound, all those beautiful bikes broken apart.

[happyslug]

11. You missed his most important Sentence:

This modulus value shows that if you were to build identical frames from the 3 materials, using the same tubing diameters and wall thicknesses, the aluminum frame would be only 1/3 as stiff as a steel one, and the titanium frame only half as stiff.

When most people compare Steel, Aluminum and Titanium they compare the same MASS of each with each other. If you compare the same VOLUME of each (Which is what Sheldon was doing here), Aluminum and Titanium come out worse then steel. This is most noticeable with Aluminum for it takes up four times the volume as the same MASS of Steel but at the same MASS is twice as strong and stiff (Titanium is even stronger at the same MASS and its volume matches up real nice with the volume of a Steel Frame, but as Sheldon does point out Titanium takes up more volume than steel, through not as much as Aluminum).

Thus when you look at the bikes, there is a volume difference between the material each is made of. In the case of Aluminum frame, it is 2-3 times the Volume of a Steel Frame, but do to Aluminum Superior strength, given the same level of MASS, you can use less aluminum and make a Frame stiffer and stronger then a Steel Frame with the same volume (i.e. Aluminum frames can be LIGHTER then a Steel Frame i.e. have less mass, but be stronger

A further factor is how the pieces are attached to each other. Aluminum and Titanium frames tend to be TIG welded, which provides a very rigid connection. Chrome Molybdenum (CR-MO) frames today are also TIG welded, but prior to the 1980s tended to be brazed with a lug connection to make the frame stiffer then the regular high tension steel frames which tended to be just welded. Most the high tension steel frame lose their stiffness do to the weakness of their welds, thus High Tension steel frames are on the bottom of the list. Aluminum and Titanium beat out Chrome-Moly do to the tendency to use TIG welding but also the greater strength of these two materials when you compare the same MASS.

Carbon have a different attachment system then the metal frame, but given the research into Carbon tend to be even more rigid, thus my line up holds up GIVEN HOW EACH MATERIAL IS USED IN BICYCLES today.