Hot answers tagged gears
21
The first rule is make sure the rear derailleur is adjusted correctly before adjusting the front derailleur.
There are three adjustments that you can do on the front derailleur:
Clamp Position
Low limit stop
High limit stop
Clamp Position
Here you can adjust the height of the derailleur, normally this is recommended as a 2mm clearance between the ...
14
Don't overthink it. Since you've got a triple, you're probably right to be in your middle ring most of the time That's normal.
In the middle ring you should have access to the whole cassette/freewheel in the back, though you might get a little extra noise as you approach the extreme gears in either direction.
You'll use the big chainring when you're going ...
12
A lot depends on the rider and what you mean by efficiency.
It is easy to keep a hub gear running well for years, but an unmaintained derailleur will become inefficient very quickly. A hub gear allows the chain to be fully enclosed, for all but the most dedicated cyclist; an enclosed chain will be more efficient as it will be cleaner and better oiled.
An ...
11
Answers for a typical 21-speed commuter I could find specs on: 20, 19, 15, 12.
20 is the technically right answer, 19 is a slightly more technically right answer, 15 is if you take into account gears that are nearly identical, but 12 is the practical usable answer.
Really, it's going to depend on your exact gear setup.
At the very least, you really should ...
11
If you can, with the chain in one of the middle cogs in the back, shift to each of the front chain rings then your front derailleur is likely in proper alignment and adjustment. This question and answer cover how to adjust the derailleur if you want to learn how to do it yourself.
What you are describing, shifting to small ring in front and small cog in ...
11
It is not necessarily "good" for your workout. If you drop into the 'easy' gear, you obviously have to pedal faster to maintain your speed. Going at a slower cadence in a higher gear will just trash your knees after awhile.
Select the gear that yields a similar cadence as when you are riding on the flats, while maintaining a similar energy expenditure.
...
10
I don't have an internal hub, but I want one for the following reasons: They are sealed and protected from the elements. They are nice for commuting because you can shift them while stopped... If you've ever stopped at a red light on a normal bike and struggled to get going again because of your gear, you can appreciate this. With an Internal hub, you can ...
10
Yes, there is a difference between front chainrings for derailleur equipped bikes compared to bikes without a derailleur.
Basically a derailleur suitable chainring "wants" to fall off. It's designed so that the chain is happy to climb onto the gear and also fall off the gear. There are various ramps for the chain to engage into.
Non-derailleur chainrings ...
9
It depends on the model you get, but the efficiency is generally comparable. Derailleurs that are in really good condition and properly lubed will be more efficient, but marginally, and will often be less efficient due to real world conditions.
At least that's what the wiki says:
http://en.wikipedia.org/wiki/Hub_gear
I have one road bike with a 3x9 ...
9
There are a number of reasons that the shifting on your rear derailleur is not working well:
The derailleur hanger (the bit of the frame that the derailleur bolts onto) could be bent. To check this look at the angle that the derailleur cage is at. When viewed from behind, it should be vertical, when viewed from above, it should be parallel to the ...
9
Excluding the two extremes (see Scott Robinson's answer), you have 19 ratios. Some of these may be very close to each other. The easiest way (although a little cumbersome) is to count the number of teeth (n) on all gears (three in front, seven rear) counting from the centerline of the bike (outwards). The ratio is given as n(front) / n(rear), e.g.:
1st = ...
9
A stretched chain will wear out gears (especially the rear cassette). You can see when this because the teeth get worn away to points - it's very obvious.
But it's very unlikely you wore out a chain and gears in 1000 Km. What is more likely is that the cable has stretched slight from new and the derailuer is out of adjustment so it is putting the chain ...
9
No.
The full gearing ratio of the bike (from your foot to the tire contact patch) is determined by four factors: the crank length, the chainring diameter, the cog diameter and the wheel diameter. Since these components can be changed independently, it is impossible to develop a uniform numbering system for a single component ("uniform" in this case means ...
9
Replacing a hub is not a "simple" procedure -- it, at a minimum, involves relacing the rear wheel, probably with different sized spokes (whose size you must accurately determine). Relacing is not beyond the abilities of a competent backyard mechanic, but is a skill that needs to be learned.
To add a second chainring you must install some sort of device to ...
8
Ultimately it's a trade-off between a wider range of gears and bigger jumps between those gears. There will always be uphills that are too steep for your lowest gear and downhills where you spin out. If you try to fix both problems with a wider range cassette (your triple already has a great range) you may find that you're never quite in the "right" gear ...
8
Gearing is commonly described in Gear Inches and to clarify, having your chain in the smallest front ring and the biggest rear cog results in the smallest gear.
Chainrings
The smallest chainring I've seen on a 5-arm crankset is a 20T, although 24T is a lot more common.
8-Speed cassettes
Shimano had a line called "Megarange" that was 11-34T. I believe ...
8
Put the chain around the big-big gears without threading it through the derailleur. Have the chain overlap by one link. Now with that length thread it through the derailleur.
http://sheldonbrown.com/derailer-adjustment.html#chain
8
Depending on the tension of the chain, you might be slightly more likely to jump, e.g. going from big to little on both front and back at the same time is increasing the slack in the chain and moving it in both directions (front to the left, back to the right).
So depending on the timing, not only will the slack need to be damped out and the indexing might ...
8
No, you will need to get a whole new cassette, the largest 3 rings are connected to each other, you cannot just purchase individual cogs. You may want to get a new chain as you will probably need to make a chain length change with jumping from a 25T to 27T or 28T largest cog.
Do you know if you have the SS or the GS?
With the SS (short cage) you can go as ...
8
Assuming you have Shimano-compatiple Hyperglide cogs: No, you can't.
The cassette body is not symmetric, the cassette fits in only one position.
You could resort to adapt the cogs with a file, though. But shifting will be problematic at least, the cogs have certain indents to make shifting smoother.
8
The problem is that any rear cluster designed for indexed shifting has directional cogs. There are ramps embossed on the sides of the cogs to catch the chain pins and lever the chain up to the next larger cog when the chain is shifted. If you somehow reverse the cogs these ramps will be on the wrong side of the cogs and will be running the wrong direction.
...
8
It sounds like you're going for cross chaining when doing the 36/12 combo (Small in front and small in back) which is generally a really bad idea and should be avoided. Also big in front and big in back.
As for the getting a better workout, you are definitely having to put more force into the pedals with keeping it in the big ring, but depending on how big ...
7
Its not about higher and lower end bikes, its about the nature of the bikes and the purposes they are used for and probably some history and snobbery too (-:
You can pay a truly staggering amount of money for a mountain bike (or a tourer or a recumbent) with a triple chainset and equally you can get something that bears a passing resemblance to a road ...
7
The simple answer is, no, it is not advisable, and yes it can cause damage. The chain uses tension to shift. Shifting with both front and rear derailleurs at the same time will remove that tension. The answer above is absolutely correct, but they are a bit too phlegmatic about the risks involved. Drop a chain due to poor shifting habits, and you risk ...
7
The likely cause is a worn cassette if the skipping is in the rear. Since the gears you use the most will wear the fastest the skip may be worse on some of them. But also look at the jockey wheels in the rear derailleur. If they have alot of wear they may not be keeping the chain aligned. If the front is worn and the back has never been replaced you are ...
7
Typically you quote gear sizes in gear inches, very basically this is the drive wheel diameter multiplied by the ratio between the two gear cogs, traditionally quoted in inches.
Also sometimes mentioned is development which is the amount of distance travelled by one revolution of the cranks (the astute will notice that is going to be proportional to gear ...
6
The cage length is what determines the rear dérailleur’s total capacity. The total capacity equates to how much slack chain the dérailleur can handle. Sheldon calculates it as
(number of teeth on largest rear sprocket - number of teeth on smallest rear sprocket)
+ (number of teeth on largest front chaining - number of teeth on smallest front ...
6
The difference probably arises because there is more tension being exerted on the chain when you are cycling as compared to the bike being up on a stand.
The screws on the dérailleur (as you probably know) are for setting it to stop at the right place (ie not to come off either towards the wheel or off the small gear). Do you have shifters which move the ...
6
I always wash off the degreaser, lube the chain, and then run it through all gears to get a bit of lube worked into everything. Don't need to lube the gears specifically.
I think the key is to be sure to wash off all traces of the degreaser. Last thing you need is residual cleaner gunking stuff up.
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