14

This is actually a matter of the force multiplication that each chainring provides, and the size/mass of each chainring. Force difference Let's propose, only for a moment that you had a chainring as big that the radius of it is almost the same as the crank length. If the rider stood to pedal while using that chainring (and using simple platform pedals). ...


13

To identify a frame firstly see if a magnet sticks, if it does it's steel, if not it's carbon, aluminium alloy or titanium alloy. If not steel look down the seat tube if it's metallic inside it could be aliminium or titanium if black and plastic looking, carbon. Tap the frame with a screw driver, aluminium and titanium will have a definite metallic 'tink' ...


12

It depends on how the fork is engineered for safety. While its plausible that the curved shape does add to some shock absorption, that is determined by the width and construction of the fork tubing. You could design a fork which was reliable and curved in aluminum or carbon or whatever, but the engineering wouldn't be the same as a steel fork. Whether the ...


12

Aluminum has gotten a bit of a bad reputation from the early generation of frames which were overly stiff. This is less the case today as manufacturing technology fixed most of these earlier problems, and bicycle designers can create formed aluminum tubes that provide compliance (i.e., vibration absorption) in one direction (e.g., vertical compliance) and ...


10

If sitting on your top tube causes damage to your bike, the bike wasn't very safe to begin with. I imagine while sitting you have at least one foot on the ground, so your entire mass is not resting on the tube. The amount of force that a frame must withstand is much greater than the weight of the rider. If simply placing 170 lbs as a static load was enough ...


10

Q: "[W]ould a competent welder be able to fix that crack[?]" No, that frame is done for. By attempting to weld such a crack, a welder would prove their incompetence. Even if you fix that crack you might find another crack on the right hand side, mirroring this crack. What is more, the crack will go considerably deeper. I had a crack at the same spot and ...


8

Others have answered the second part "what are the differences..." Here's an answer for the first part "why not many at the dump" In in my city 2015 light grade clean steel is worth $0.02/kg. Aluminium extrusion is worth $1.83/kg. Brass like nipples is $3-$4/kg and stainless steel is about $0.90/kg. Recycling metal pays money, but I'm not going to ...


8

A crack developing there, is most likely too much seat post out of the frame, or in actual fact, not enough seat post being in the frame. The biggest problem with a crack in this location, is that it then causes most force to be placed on the join between the top tube and seat tube. You also have to think about what would happen if the frame were to suffer ...


8

Result DISMAL FAILURE I attempted to use a large 12" adjustable spanner to gently tweak the rim back to place. On the first pass along it worked okay, and took out about a third of the offset. It was better but not right. On the second pass along I felt something crunch. It felt like snapping a thin green twig where the fibres break but don't part. ...


7

If it were a steel frame and fork there would be no question -- steel lasts nearly forever, even when moderately rusty, and can take all sorts of abuse. Aluminum is a bit less robust, but if it only has "a few thousand" miles on it (and not 30,000) and has not been abused (or hit by a car) then it should be good. The problem with aluminum is that it can ...


7

I can't see your specific rims from here, but plenty of bikes back in the 70s and 80s had rims that width capable of handling 90-110 PSI. And I definitely wouldn't run a 1-1/8" tire at 65 PSI. I'd imagine that the rims, if designed for tires that narrow, should be able to handle 80 PSI or so.


7

The frame is 100% trash. Do not attempt to use it at all. What you can do is to carefully remove everything from the frame. Discard the frame, and now you have a whole bunch of valuable parts. You can either buy a new (possibly second hand) frame, or just sell the parts to finance the purchase of another bike. There are a few parts you won't be able to ...


6

The problem I had was getting the ammonia to the corrosion. I hung the bike upside down by both tires so the seat post was vertical. You can either remove the bottom bracket or as I did the bottle cage screw and fill the seat post with straight ammonia. If possible plug the hole so the ammonia doesn't evaporate. I let it hang for 2 days. I then laid the bike ...


6

Good question! There are a couple important reasons for the differing materials: Wear: Steel lasts longer than aluminum, plain and simple. So why not use steel on all the rings? The larger rings have ramps on the sides that facilitate shifting and cannot be flipped as the ring wears. The granny ring can, therefore it can last a lot longer. Flexion/Bending: ...


6

I am posting this as an answer but it is more of a long comment. The information I have is from the place I trust to do carbon repairs. According to Hot Tubes aluminum and the carbon resin react. The aluminum must be sealed to get a good bond. The materials are not your hardware grade epoxy. If we were talking about a fishing rod or something that would not ...


6

First, try to find a modern wheel that's the right size. They are still made and you can get very shiny ones that will match the bike very nicely. Or get a 120mm fixie hub and add 3mm of spacers each side. If you must use a modern wheel, try to shrink your hub. Many hubs have washers between the locknuts and cones, or other spacers. If you can remove even a ...


6

Abraham Olano won the 1998 Vuelta on an alloy frame. That might be the last Grand Tour win on alloy - as the Vuelta is the last Grand Tour of the year.


5

Do you know the history of the bicycle (crashed, etc)? While bicycle geometry\components\preferences have changed over the last 12 years, the life span of well cared for aluminum frame and carbon fork are much longer. Clean the frame and fork and give it a thorough examination. Look for: Major dents in the frame that may compromise the integrity (minor ...


5

2 things: While many older forks used replaceable steerer tubes, the steerer tube is still specifically shaped for that fork. Tubing will not do it. You need an oem replacement steerer tube. Nobody makes forks like that anymore, hence the lack of google results. Also, that steerer tube in the photo looks to be steel, and should not be replaced with ...


5

I have an identical problem, having been rinding the bike without seat clamp for more than two years now. I suppose you have already read something about it, if not I recommend Sheldon Brown on the subject. But I must warn you that the ammonia theory didn't work for me, and I tried ammonia on some aluminum sample parts without any visible effect (corrosion, ...


5

According to this article, the last Tour De France win on an aluminum frame (a Bianchi ridden by Marco Pantani) was 1998. It also says that the last TDF win on a steel bike was 1994. It's interesting that aluminum had such a brief run.


5

There are a lot of more potentially useful avenues to investigate first, because you feel that chamois pad quality is not the culprit next most obvious choice is the saddle: Stock saddles are often not very high quality. They are also typically too soft (aka not supportive) which will cause problems on longer longer rides. Adding to this, if you still have ...


5

I had an exactly same problem: Ritchey WCS seatpost, Merida frame (both alu alloy) and a lightweight clamp, like in @Frisbee's answer. What I tried: Beefy clamp with various torque settings. Didn't help at all. PVC tape. Helped, but didn't last long. More torque on a lightweight clamp. I snapped it in half with only 6Nm. Hair spray. To my surprise, it ...


5

Good epoxy is known to bond metals, especially aluminum very well. Make sure the surfaces are clean and slightly rough for a better bond. I use the same two part epoxy hobbyist aircraft builders use for fixing pretty much anything, including broken ceramic mugs, small broken metal things and even as an insulator on the bottom of PCBs to prevent any shorts. ...


5

Since you have a relatively "flat" spot there (at least flat in the longitudinal direction) you have two options: You can epoxy on a replacement boss I did this on a recent Al frame with the exact same problem. I bought a metal (steel) cable boss from the local bike builder and epoxied it myself. I used Loctite's Metal/Concrete epoxy since it's designed ...


5

I have a 1998 aluminium road bike, and it made creaking noises in the stem when pedaling hard. Could replicate this by siezing the bars while stopped and wiggling. So I tightened the quill stem and the noise went away. Its just a bit of play in the steerer tube/quill stem fixing. Since you're asking, a frame should outlive you, assuming no crash damage ...


5

DRH has pretty much answered it in the comments, but the variation can be a lot and its going to be hard or impossible to tell just by looking at a frame, especially if you encounter a counterfeit (more of a problem for carbon fiber, but still; this can be a safety issue if the bikes aren't properly tested). Bicycles have been commonly made out of aluminum ...


5

You actually point out two important characteristics in your photos: welds and hydroforming. The more expensive frame (looks like specialized bikes) has shaped tubes and very clean welds, while the second frame has straight tubes and messy welds. The shaping of tubes (hydroforming) isn't just for looks. By shaping the tubes (in addition to butting) the ...


5

Presumably you are looking for a cheap bike to ride in harsh winter conditions. The advertised price of 35,960₽ is about US $615 (at the time the question was asked) which would be considered a quite inexpensive bike here. Your choice or tires is going to make a much bigger difference than a carbon fiber vs aluminum fork. An aluminium fork will be fine, but ...


5

Yes it's safe to ride. That "line" it's just a crack on the paint surface, I would suggest painting it with something like clear nail poslish jusft in case. A dent on a commuter bike is nothing to worry about.


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