65 votes
Accepted

How is this damaged aluminium frame likely to fail?

How is this damaged aluminium frame likely to fail? Sorry. It's not going to fail, it has failed. It's no longer ridable. The head tube is near vertical making the steering very unstable and the ...
Argenti Apparatus's user avatar
25 votes

Is it safe to ride an aluminium bike with a big top tube dent?

My opinion, which is very much my own, is that this is safe to ride home and may provide some level of “emergency use” where no other bike is available and you need to get around for a short while, ...
Noise's user avatar
  • 13.7k
20 votes

Is it safe to ride an aluminium bike with a big top tube dent?

I’m not an engineer. With that caveat, I think this frame is likely to fail. It may depend on how thick the tubing is, and if you see little cracks anywhere on the tube, I would stop immediately. ...
Weiwen Ng's user avatar
  • 29.7k
19 votes

I have a bent aluminum rim on my Merida MTB. Is it damaged beyond repair?

UPDATE That aluminium rim is cracked. You should scrap it immediately. The crack is a weak point and if you try and straighten it, the crack will widen. The air pressure in the tyre will lengthen ...
Criggie's user avatar
  • 121k
18 votes

How is this damaged aluminium frame likely to fail?

Oh, that frame is done. It’s not worth saving a few hundred bucks now and spending thousands in the hospital later. Make sure to check over the rest of the bike, especially the fork. It might have ...
MaplePanda's user avatar
  • 15.4k
18 votes
Accepted

What are the most basic parts of a bicycle which cannot be upgraded over a period of time?

Certain parts of a bicycle are more easily upgradeable than others, while other types of upgrades require special tools, much more money investments or are limited to whatever standards are used in ...
Grigory Rechistov's user avatar
18 votes

14 "Trashed" bikes acquired for free. Worth repairing and reselling? What do I look for?

From having maintained cheap bikes using other bikes as parts donors, even dismantling some to provide parts for others you're likely to need to buy some bits like chains and cables. They're cheap but ...
Chris H's user avatar
  • 57.3k
17 votes

Is it safe to ride an aluminium bike with a big top tube dent?

I would ride that bike as little as possible before replacing it. Being aluminium, it will fail rapidly once the metal tears properly. If it were steel with the same damage, it could still outlast ...
Criggie's user avatar
  • 121k
16 votes

14 "Trashed" bikes acquired for free. Worth repairing and reselling? What do I look for?

This is pretty much how I started. First of all: If the bikes are cheap-ish with cheap-ish components, you will never even make a minimum wage. But that need not stop you. First, on a cheap bike if ...
Burki's user avatar
  • 1,204
15 votes

What are the most basic parts of a bicycle which cannot be upgraded over a period of time?

Any and every part of a bicycle can be replaced, including the frame. (Many people would probably regard a different frame as a different bicycle though.) You ask whether there are components that '...
Argenti Apparatus's user avatar
15 votes

Drilling hole in aluminium frame

Do not do that. Although the question you referenced is about carbon fiber, the answer mostly applies. Aluminium alloys used in bicycle frames are quite fragile. Drilling may easily start cracks that ...
Vladimir F Героям слава's user avatar
14 votes

Very tiny dent on new aluminium frame -- anything to be worried about?

That is your bike's first "war wound" and should not compromise the integrity at all. It is disappointing to have a new-thing and is now no-longer showroom clean, but that's life - keep ...
Criggie's user avatar
  • 121k
14 votes

I have a bent aluminum rim on my Merida MTB. Is it damaged beyond repair?

When dealing with dents like in the first photo only… I get dents like this all the time. I straighten them out with a crescent (adjustable) wrench. Start with small movements to get a feel for how ...
Paul H's user avatar
  • 3,474
13 votes
Accepted

Are curved aluminum forks safe?

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. ...
Batman's user avatar
  • 46.1k
13 votes

How is this damaged aluminium frame likely to fail?

The problem with aluminum is, that it tends to break abruptly. Aluminum can bend under pressure, but it does no stretch significantly under tension before being ripped apart. You get no warning, you ...
cmaster - reinstate monica's user avatar
12 votes
Accepted

What's the strongest way to bond a cable stop to an aluminum frame?

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 ...
tir38's user avatar
  • 1,058
12 votes

carbon vs aluminium frame vibration absorption? bumpiness?

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, ...
Rider_X's user avatar
  • 30.5k
12 votes

Aluminum seatpost broken into a steel frame

That's a challenge right there - I hope the bike wasn't being ridden at the time it failed ! Clearly the post is dead, so damage to that is okay. You want to save the frame. Remove the seatpost ...
Criggie's user avatar
  • 121k
11 votes

Is it ok to sit on the top tube of my Cannondale CAAD12 (2017 model)?

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 ...
CRoberts's user avatar
  • 511
11 votes
Accepted

Crack/fissure in the headtube

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 ...
gschenk's user avatar
  • 9,610
11 votes

What does the frame material name of "SC7 Scandium" mean?

Yes. Scandium is an element with atomic number 21. It is rare with the annual worldwide production being 15-20 tonnes total, so the pure metal commands a price of over $140 USD/gram, and Scandium ...
Criggie's user avatar
  • 121k
9 votes

Is this aluminium rim saveable?

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 ...
Criggie's user avatar
  • 121k
9 votes
Accepted

Can I cut the steerer tube with a pipe cutter?

A pipe cutter is an excellent tool for this application. Properly used it results in a perfect, burr free cut that is 90° to the longitudinal axis of the steer tube. The outer aspect of the cut ...
Jeff's user avatar
  • 9,777
9 votes

Aluminum seatpost broken into a steel frame

I can imagine two approaches. Use an internal bearing extractor. This is a split cylinder that can expand to clamp against the inside wall of the seatpost, much like a quill stem clamps against the ...
Adam Rice's user avatar
  • 29.2k
9 votes

14 "Trashed" bikes acquired for free. Worth repairing and reselling? What do I look for?

I'll note here that in many areas there are groups that refurbish used bikes and donate them to groups which in turn give them to disadvantaged people. I was in a group like this until about 2 years ...
Daniel R Hicks's user avatar
9 votes

Should I upgrade my entry-level bike?

Shopping advice of off topic, so I am not making a recommendation on make/brand/model. If you are unhappy with your current bike, first thing is work out why - is it the quality of the bike, or the ...
mattnz's user avatar
  • 49.1k
9 votes
Accepted

Is it safe to strip paint + polish an aluminum handlebar or seatpost? Will this affect their diameter?

Yes - removing the coating will remove some small amount off the dimension. However, it may not be enough to matter. It really depends on how aggressively you apply the wire wheel. So instead, ...
Criggie's user avatar
  • 121k
8 votes

Steel vs. Aluminum Wheels

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. ...
Criggie's user avatar
  • 121k
8 votes
Accepted

How long will this alum frame last?

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 ...
Henry's user avatar
  • 399
8 votes

Aluminum seatpost broken into a steel frame

There's no pleasant option here but I think in lieu of very specialized tools (like a slide hammer collet that could grab it securely enough), you're limited to cutting it out. Use a hacksaw blade ...
Nathan Knutson's user avatar

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