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Old 07-08-09, 05:48 PM   #1
Leah
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How do you change a 21-speed into a 10-speed?

Hello,
I have a Trek 7500 that I want to change from a 21-speed to a 10-speed.
Do I just have to take off the gears and buy new ones, or is it just an ajustment that I have to make?
Help!
Thanks,
Leah
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Old 07-08-09, 05:50 PM   #2
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Why would you want to make your bike even less versatile than it already is?
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Old 07-08-09, 05:51 PM   #3
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oh, boy, where to begin...

new wheel, new cassette, new shifters, new chain
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Old 07-08-09, 05:53 PM   #4
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do you mean you currently have a triple in the front and seven speeds in the back meaning 21 speeds?

When people here refer to a 10 speed they mean 10 in the back and either 2 or three in the front (20 or 30 speeds)
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Old 07-08-09, 05:53 PM   #5
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I dunno... Let me know, because I was thinking of switching out the 6 speed in my BMW M3 over to a nice 3 speed.
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Old 07-08-09, 06:04 PM   #6
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Well Leah your going to get lots of good advice but my thought is have you really thought this through//when you have read and studied the various options you may have a different idea /Ithink I might do 3 on the front derailier and 3 on the rear so I had a 9 speed/Kenneth
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Old 07-08-09, 06:16 PM   #7
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This is a hybrid, no? I'd just leave it be. 7 speed parts are fairly cheap, so if you need to buy spares, it will be more economical to replace the 7 speed parts when they wear out.
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Old 07-08-09, 06:39 PM   #8
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Moved this to Bicycle Mechanics - but my advice: leave it alone.
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Old 07-08-09, 08:09 PM   #9
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I guess Leah wants that "10 speed" to go along with her disco ball, lava lamp and bell bottoms.

Leah, back in the day, bikes were called "10 speeds" because they had five gears in the back and a double chain ring up from, 2X5 hence "10 speed". Today a bike's speeds are a reference to a how many gears are in the back. 7 cogs(gears) = 7 speed, 8 cogs = 8 speed, etc. The crank gears are called "chain rings". If you have 2 chain rings, you have a "double", 3 chain rings and you have a triple. So, if you have 7 gears in the back, and 3 chain rings up front, you've got a 7 speed triple, not a "21 speed". Why you would want to change this back to a 1975 configuration, I haven't a clue. If you really insist, I'd think you'd be better off trading your current ride instead of ripping out gears. Tell you what, give me your 7500 and $100 cash, and I'll give you a spiffy lime green Schwinn Continental "10 speed". I'll even throw in a shiny chrome spoke protector. What a deal!
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Old 07-09-09, 10:42 AM   #10
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I think Leah gave up on us and took her 21-speed home.
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Old 07-09-09, 11:20 AM   #11
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Quote:
Originally Posted by Leah View Post
Hello,
I have a Trek 7500 that I want to change from a 21-speed to a 10-speed.
Do I just have to take off the gears and buy new ones, or is it just an ajustment that I have to make?
Help!
Thanks,
Leah
Remove 11 gears.
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Old 07-09-09, 11:26 AM   #12
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I want to be kind to newcomers, but sometimes the questions are so strange that it crosses my mind that some are trolls. I'm not saying Leah is. She might be misguided by her local experts. And she may not be a regular, which would explain the apparent hit-and-run posting. But who can say?

Leah, if you're out there, please explain further. We'd like to help!
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Old 07-09-09, 01:26 PM   #13
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Originally Posted by noglider View Post
I want to be kind to newcomers, but sometimes the questions are so strange that it crosses my mind that some are trolls. I'm not saying Leah is. She might be misguided by her local experts. And she may not be a regular, which would explain the apparent hit-and-run posting. But who can say?

Leah, if you're out there, please explain further. We'd like to help!
What's the point of a troll, anyway? I thought they just exist to pi$$ people off of competing things... Chevy guys posting of all the crap that Dodge has on a Dodge forum, for example... They can also just post absurdly stupid questions?
Wow... I wonder if I've been called a troll...
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Old 07-09-09, 03:24 PM   #14
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If you have to ask, you'll never understand the appeal of trolling.
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Old 07-09-09, 03:33 PM   #15
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Y'all missed the easy answer to the possible troll - two minutes work twiddling derailer limit screws will create a "10 speed" at zero cost. Job done.
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Old 07-09-09, 04:10 PM   #16
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No, we saw that, but sometimes, understanding the question and what's behind it is more useful than answering the question.
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Old 07-09-09, 05:33 PM   #17
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Probably hanged herself from a rafter in the garage. Good job. You've killed.
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Old 07-09-09, 08:41 PM   #18
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Okay, I obviously don't know that much about bike mechanics. Many of you have pointed that out. The only reason that I am even asking is that my bike seems to have many repeats of the same gear (like 1/7 feels the exact same as 2/4 and 3/1, etc.). I probably have less than five different feeling gear settings anyway. I don't want to change my bike to make it less versatile. I want to actually have a good amount of differentiating gear settings. I have done the basics with the gears like greasing them and such, but I don't really know how to do much else. I volunteer fixing up kids bikes, so I really have no experience fixing anything more complicated than a coaster brake. Sorry -- I realize I was really unclear before.

Leah
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Old 07-09-09, 08:53 PM   #19
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watch this video and it will solve your problems and tell you why your bike is like this http://bicycletutor.com/gear-shifting/
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Old 07-09-09, 08:54 PM   #20
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Just... don't move your shifter so far.
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Old 07-09-09, 08:56 PM   #21
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Don't mind these YeeHaws (myself included). Every newcomer gets razzed. The duplication of gears is a well-known and common phenomena. You can measure the gears on an inch-scale with a formula I can't currently remember. This helps to prevent this if you are re-building your drivetrain or just swapping out a cassette. Someone should come along with the formula.

Here are a couple of resources to get you familiar with the basics of bike-mechanics. The first one is a series of short videos giving demonstrations of many situations:

http://bicycletutor.com/

And this is the venerable Park Tool repair site. Just point to a part/area on the bike, and you'll get instructions:

http://www.parktool.com/repair/

And finally we have the personal site of Sheldon "Our Lord" Brown. Until recently, the greatest living resource on all-things bicycle:

http://sheldonbrown.com/harris/#articles

This should give you a good background.

Happy Trails!
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Old 07-09-09, 09:20 PM   #22
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Thanks
I'm completely wiped today, but I'll definately get to work on fixing up my bike soon.
Those sites look like they will be a lot of help.

On a different note:
Do you think a hybrid or a road bike would be better for someone who commutes 50+ miles per week in the city?
I'm pretty uncertain about the future of my bike; I think it might be about time to trade up.

Thanks again,
Leah
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Old 07-09-09, 09:37 PM   #23
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Quote:
Originally Posted by Leah View Post
Thanks
I'm completely wiped today, but I'll definately get to work on fixing up my bike soon.
Those sites look like they will be a lot of help.

On a different note:
Do you think a hybrid or a road bike would be better for someone who commutes 50+ miles per week in the city?
I'm pretty uncertain about the future of my bike; I think it might be about time to trade up.

Thanks again,
Leah
50 miles a week is 10-ish miles a day... if you're riding every day. I cover 50 miles a week if I ride to work twice a week. (I heard of one lady who rides a 60+ mile round trip every day, then goes for training rides afterwards. Sheesh.)

Ummm... are you unhappy with the way your current bike rides? Do you want to go faster? Are you bothered by other bike commuters beating you to the next stop light in the Red Light Grand Prix (a real issue here in Portland- some of the bike routes are getting jammed).

IMO, if you're happy with your position on the bike, perhaps a swap for narrower, higher pressure tires would help. Your hybrid probably has 700 x 35C tires, so you could probably put 700 x 28C tires without a problem. Narrower tires could run into pinch-flat issues.
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Old 07-09-09, 09:44 PM   #24
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Yeah, I'm car-free, so if I want to get somewhere, it is almost always on my bike. Add that to a 6-mile-per-weekday commute, and it definately begins to adds up.My main problem (other than the gear thing, of course) is that my bike is fairly heavy. I live on top of a gigantic hill, so anywhere I go involves getting back up it.My bike is definately worth the $250 I paid for it a few years ago, but that doesn't really mean much with a bike. I've been looking for a replacement on craigslist because I really don't have the money for a new bike, but not a ton has come up in my size. I've been weighing whether its cheaper to just fix up my bike or get a new one, and whether fixing it up would be worth the time and money anyway. So far, its been pretty inconclusive.
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Old 07-09-09, 09:52 PM   #25
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Quote:
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Yeah, I'm car-free, so if I want to get somewhere, it is almost always on my bike. Add that to a 6-mile-per-weekday commute, and it definately begins to adds up.My main problem (other than the gear thing, of course) is that my bike is fairly heavy. I live on top of a gigantic hill, so anywhere I go involves getting back up it.My bike is definately worth the $250 I paid for it a few years ago, but that doesn't really mean much with a bike. I've been looking for a replacement on craigslist because I really don't have the money for a new bike, but not a ton has come up in my size. I've been weighing whether its cheaper to just fix up my bike or get a new one, and whether fixing it up would be worth the time and money anyway. So far, its been pretty inconclusive.
Ah, I see...

IMO, a conventional road bike would probably be a better hill climber than fixing up a hybrid. On the other hand, putting a lower stem and straight handlebars might be enough of a change to satisfy your hunger for hills. How well either bike fits you will be a key element.

I know- pretty wishy-washy. "Inconclusive" is my middle name! (I think.)

Talk to the local racing club- many times someone is trading up, down, or sideways for the latest "big thing". A "racing" bike might not be a good commuter, but you might luck out. An older road bike that fits you and accepts slightly fatter tires (as above- 700 x 28C) sounds like it would fit the bill.
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