Gears 'n sprockets 'n what not
01-06-19, 08:56 PM
#26
Senior Member
ok, don't beat me up too much on this...i want to know what the deal is with two sprockets (gears) in the front vs three in the front. my bike is apparently a bit older than the newer generation (10ish years), i have three and they all serve me well. most newer models i see have two in the front. advantage? can't possibly be weight, can it? is it is just fewer to shift through? i presume that the ratio with the back cassette compensates somehow but what is the real cost/trade off?
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and it is sprockets or gears or metal circles with pointy things around?
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and it is sprockets or gears or metal circles with pointy things around?
a key on a typewriter or computer keyboard used to switch between two sets of characters or functions, principally between lower- and upper-case letters.
noun: shift key
01-06-19, 09:54 PM
#27
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to all others, thanks for the info. it was a good read. never thought it would generate such an amount of response.
-scott
01-06-19, 10:17 PM
#28
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wow, i was happily reading all the responses i got to a genuine question until i got to this one. what in my post implies that i don't know how to shift? i only made an observation about what my 10ish year old ride has and what i see on newer rides. i'm quite happy with three in the front. i ride hills and i need that little guy when going up and i use that big 'un going down.
to all others, thanks for the info. it was a good read. never thought it would generate such an amount of response.
-scott
to all others, thanks for the info. it was a good read. never thought it would generate such an amount of response.
-scott
01-06-19, 11:41 PM
#29
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I still like triples for loaded touring and hauling cargo (I think). At least they are worth experimenting with. But, the double is fine for most ordinary riding including typical hill climbing. Probably for those wild days of lots of 20% climbs, I'd be better off simply installing a larger cassette.
I used to be a huge triple fan--but I just cannot justify it for most uses.
01-07-19, 07:11 AM
#30
Cycleway town
01-07-19, 07:23 AM
#31
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George Jetson worked at Spacely Sprockets. Their competitor was Cogswell Cogs. I just wanted to remind everyone of that.
01-07-19, 04:06 PM
#32
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01-07-19, 07:33 PM
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So it's really like a diesel truck with a 13 or 15 speed transmission, or an old 5&4 or something. There are lots of gears and the design was to allow sufficient overlap so that if you dropped off one of the front chainrings (say 50 to 40) you'd have enough in the back to get back up to speed.
EX: Let's say you are climbing a leg-burn grade at about 12 MPH and you are down to the lowest possible speed choice on the big ring up front - so it takes a few seconds to change a front ring and few more to scale back up the rear "cogs" to get to maybe 11 MPH (you lost momentum shifting, but have recovered to the next logical speed for that hill). But, now if things get even steeper, you are OK because you are on the middle ring up front and you have a lot of "cogs" left before you have to drop to the granny gears (the littlest chainring up front - often a 22).
Mountain bikes carried 3x8 sets for years, maybe decades ... Usually 22-32-44 or 46 up front. Original 24 speed bikes had like 11-28 out back. But they soon discovered that 11-30 was nice, 11-32 was nicer, and eventually they got to 11-40 out back. If you look at the cassettes, it looks evenly spaced for from small cog to big. As you get to the most modern of the 3x8's, the cassettes look exponential. They still start at 11, but the spread gets wider faster. I have a couple of 11-28 and 11-30, one 11-34 and a 11-40 on the way to play with.
In mountain biking the slope can, and does change, very quickly as you approach rooted areas near a big tree bowl and then a drop to a bit of "dirt" and back to a rock out-crop, etc. So you shift a lot. You load that trigger shifter so as soon as the power comes off for second it shifts and you are back into the pedals. Road riding gives you a bit more time to plan your shifts.
And the spread over-all determines the kind of rear derailleur needed. Older short leg derailleur's were adequate for 11-30 out back, but as the spread became more pronounced, the derailleur had to become longer and longer. Spring tension went up. Now the have friction clutches built in to stop chain-slap and chain-drops as the bike bounces over roots and rocks. The long legged derailleurs do take a beating on rock strikes and stuff ...
The move to one speeds up front was to get away from double shifting. Having to move off a big ring up front and then recover out back. You are now just going up and down out back. But mountain bikes seldom need to reach road speeds by pedal power. They can get to 40 or 50 going down hill often enough. But their top pedal-speed is modest at best ...
EX: Let's say you are climbing a leg-burn grade at about 12 MPH and you are down to the lowest possible speed choice on the big ring up front - so it takes a few seconds to change a front ring and few more to scale back up the rear "cogs" to get to maybe 11 MPH (you lost momentum shifting, but have recovered to the next logical speed for that hill). But, now if things get even steeper, you are OK because you are on the middle ring up front and you have a lot of "cogs" left before you have to drop to the granny gears (the littlest chainring up front - often a 22).
Mountain bikes carried 3x8 sets for years, maybe decades ... Usually 22-32-44 or 46 up front. Original 24 speed bikes had like 11-28 out back. But they soon discovered that 11-30 was nice, 11-32 was nicer, and eventually they got to 11-40 out back. If you look at the cassettes, it looks evenly spaced for from small cog to big. As you get to the most modern of the 3x8's, the cassettes look exponential. They still start at 11, but the spread gets wider faster. I have a couple of 11-28 and 11-30, one 11-34 and a 11-40 on the way to play with.
In mountain biking the slope can, and does change, very quickly as you approach rooted areas near a big tree bowl and then a drop to a bit of "dirt" and back to a rock out-crop, etc. So you shift a lot. You load that trigger shifter so as soon as the power comes off for second it shifts and you are back into the pedals. Road riding gives you a bit more time to plan your shifts.
And the spread over-all determines the kind of rear derailleur needed. Older short leg derailleur's were adequate for 11-30 out back, but as the spread became more pronounced, the derailleur had to become longer and longer. Spring tension went up. Now the have friction clutches built in to stop chain-slap and chain-drops as the bike bounces over roots and rocks. The long legged derailleurs do take a beating on rock strikes and stuff ...
The move to one speeds up front was to get away from double shifting. Having to move off a big ring up front and then recover out back. You are now just going up and down out back. But mountain bikes seldom need to reach road speeds by pedal power. They can get to 40 or 50 going down hill often enough. But their top pedal-speed is modest at best ...
Last edited by BrocLuno; 01-07-19 at 07:45 PM.
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