59
votes
Accepted
Why do men's bicycles have a top tube while women's bicycles don't?
Frames designed for women do have that part - its called a top tube.
Historically women wore skirts, so a lower frame in the middle made it easier to mount and dismount, and was less likely to ...
- 121k
38
votes
Why do men's bicycles have a top tube while women's bicycles don't?
Back in the day, women primarily wore dresses, and getting the dress over the top tube was difficult and awkward. So the women's bike was developed with a slanted or sloped top tube so women could ...
- 704
35
votes
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Why only ball bearings on bicycles?
I think several of your assumptions are incorrect:
no high speeds: rim dynamos spin quite fast, up to 10,000rpm, and that does require effort on the part of the designers. Typically the drive wheel ...
- 23.3k
19
votes
Pedal spin resistance a good thing?
There does seem to be an upside down U-curve of spinniness on pedals with the horizontal axis being price and the vertical axle being how many rotations it makes when spun by hand.
Cheap pedals are ...
- 29.1k
12
votes
Accepted
Got a new frameset, don't know why I need this split ring collar?
That looks like the compression ring for a threadless headset.
Images by keithonearth on Wikimedia Commons, reproduced under Gnu free documentation license
More information found at Sheldon Brown
- 20.7k
11
votes
Why only ball bearings on bicycles?
Firstly I disagree with the comment about high speed. The highest velocity bearings are plain: crankshaft bearings in a full size car engine are plain, whereas in a radio controlled model, ball ...
- 411
11
votes
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Choosing the proper bearings for replacement
Bearings are of standardised dimensions. In your case 6902 is 15 x 28 x 7 (inner diameter x outer diameter x width) and 6903 is 17 x 30 x 7 (which you probably got from Google).
Thus, dimension-wise, ...
- 4,281
10
votes
What is "crank preload"
Good question. This is a term that is frequently referred to but not clearly defined. I added a definition of preload to the terminology index under the bearings page.
Consider your crankset. Preload ...
- 29.7k
10
votes
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Pedal: Platform came off axle which remained in crank
I found a component diagram for these pedals here.
Here's the main diagram:
Looks like all the bearings are mounted onto the axle and secured with a bearing preload and lock nut at the outboard end. ...
- 75.5k
10
votes
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What range of rotational speed for bike wheel bearings?
Searching for "ndm rotational speed" finds that D and d are outer and inner diameters of the bearing. n is not the usual symbol for speed, but neither is the final unit "millimeters per minute divided ...
- 21.8k
10
votes
Chain is jumping regularly on every cog at every speed?
When cogs are worn, new chain makes things worse. In my case, the old chain was skipping time to time but the bicycle was rideable. With the new chain the two fastest gears went completely unusable. ...
- 7,482
10
votes
Can QR cause Brinelling in hub bearing?
Brinelling happens when the contact stress exceeds the limit of the material. I don't believe you can achieve that alone with a too tight QR, although it sounds like your bearings are so tight that ...
- 18k
9
votes
Pedal spin resistance a good thing?
The difference is in the lubricant. Ball bearings need to be lubricated with a sort of grease. This grease is in your wheel hubs and also in your pedal bearings. The grease is gooey. Gooeyness ...
- 53.4k
9
votes
Got a new frameset, don't know why I need this split ring collar?
It is indeed a compression ring, David D’s diagram is helpful to illustrate the following:
What it does is transfer the force of the cap bolt to the inner face of the cartridge bearing. That then ...
- 12.7k
9
votes
Accepted
Off brand bearings for hubs?
With bike hubs you are generally safe buying a high-quality generic replacement as long as it's actually the same bearing type, same dimensions, same kind of shields, and with 100%-ish grease fill. ...
- 81.9k
9
votes
Do I need to remove this DT Swiss ring nut? (360 hub)
DT Swiss states that on pawl type rear hubs, the ring nut must be removed in order to remove the driver-side bearing. See section 2.7, page 9, in this manual from DT Swiss:
https://www.dtswiss.com/pmt/...
- 846
9
votes
Is this a sign for bearing maintenance?
I've never been in this situation, but here is my opinion. I would take the fork out, or have the store do it, and inspect things. You can check if your bearings feel gritty, which indicates wear. If ...
- 29.7k
8
votes
Accepted
Can I replace this bearing? (MTB head tube)
It's the most common kind of threadless headset. External cups, caged bearings. It uses a 5/32x20 retainer (bearing size x count), which again is the most common type and available online and at most ...
- 81.9k
8
votes
Accepted
Dent in bearing cone, try to get a new one, or can I keep riding like this?
Anywhere there is a cone, there is also a "race" that the bearings sit in. The cone holds the bearings in place against the race. The picture you have posted shows the very definition of "pitted cone"....
- 16.2k
8
votes
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Front wheel bearings change
Put the 3/16" bearings back in, even if you have to buy some fresh ones.
Your quarter-inch bearings are not sitting in the bearing raceway right which is causing the too tight/loose problem.
They ...
- 121k
8
votes
Accepted
Should there be grease in my steel frame's tubes?
Some mechanic might have put a liberal amount of grease in the BB shell and also in the head-tube prior to assembly. Then copiously greased the seat-post as well. Grease has a tendency to migrate, ...
- 8,269
8
votes
Just replaced axle on rear wheel. It is loose at first but as soon as I ride it, it tightens and wheel no longer rotates. Help!
I have sometimes made the mistake of not tightening the locknuts enough, causing the rotation of bearings to drag the cone, tightening it enough for the bearing to bind.
The solution is to properly ...
- 12.4k
8
votes
Accepted
How/where can I find replacements for these 'wheel bearing caps'?
Metal dust shields would be the common name to the extent there is one. The usual protocol is to handle them with care and never remove them, because they're difficult to replace. The OEM hub ...
- 81.9k
8
votes
Cup and cone bearings: better a little tight or a little loose?
As loose as possible without play. Bearings are supposed to have some amount of preload, which is a fancy name for being a bit tight as opposed to being loose. There should never be play once adjusted ...
- 81.9k
8
votes
Accepted
How is the load of the bike transferred to the hub cartridge bearings with a through axle?
There are two ways, depending on the type of the hub.
Most hubs use a separate axle around the thru-axle. So for example if you have a 15mm thru axle in the front, you would have a 18mm axle around ...
- 18k
8
votes
Is this a sign for bearing maintenance?
I had a similar situation a few months ago. Any time it rained or the bike got wet, there ended up with brown rusty smears running out of the bottom of the headset.
Mine uses a semi-integrated headset,...
- 181
8
votes
Alternative to Shimano TL-PD40 Pedal Tool?
It is possible to remove it using vice grips or slip joint pliers, but I wouldn’t recommend planning to do that over and over. The plastic will get chewed up very quickly. As a last resort, sure, but ...
- 15.4k
7
votes
Accepted
How to properly remove bearings from shouldered-axle track hub
With a trapped axle like that you use a hammer, ideally a soft face one or I use a bit of wood as a pad. Hold the block against the axle, tap the block with a hammer. Holding the wheel in your hand ...
- 23.3k
7
votes
Accepted
When to replace FS bearings?
First, not all full suspension bikes use bearing for all pivot points, and some bikes don't use them for any. They use bushings instead.
That said, assuming you have bearings at all points on your ...
- 29.9k
7
votes
Accepted
When overhauling bottom bracket bearings, is it possible to replace loose bearings with cartridge bearings?
Can you clarify if you mean a cup and cone housing, to change from loose bearings to bearings in a metal retaining cage? Like this:
ANSWER 1 These can totally be used instead of loose bearings. ...
- 121k
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