Touring - Need some lower gears-help

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babysaph
04-16-06, 02:29 PM
How do I get some lower gears for my mtn bike. I am planning on touring this summer fully loaded and want the lowest gears I can get. I have a Giant sedona mtn bike that I converted for touring. I have no idea what gears it has. Is this something I can do myself? Where can I get the gears online? How do I know what kind of gears I have and what kind to get.
roadfix
04-16-06, 02:34 PM
I have no idea what gears it has. How do I know what kind of gears I have and what kind to get.
For starters, did you try looking at them and counting how many teeth there are if not indicated?
babysaph
04-16-06, 02:42 PM
Yea, I have 3 rings up front and eight on the back. Can't see anywhere on there where it is written what size they are. Just looking for this newbie doesn't help much. Oh yea there is teeth on the rings in both front and back LOL
count the number of teeth on each ring so we have an idea what gearing you have. if you already have a 22-34-44 on the front and a 14-34 or something on the back, i don't think you can go much lower.
MTBs are usually geared pretty low to begin with and you're not likely to get much lower. Chances are that unless you plan on tackling some extremely steep hills the stock gears should be fine.
acantor
04-16-06, 06:50 PM
To determine your lowest gear, count the teeth of the SMALLEST gear in the front, and the LARGEST gear in the rear.
The number of teeth in front is probably between 22 and 30.
The number of teeth in the back is likely between 28 to 34.
Divide the front number by the back number: e.g., 22/30 or 24/34 etc. This calculation will give you a value between 0.6 and 1.1.
If the result is between 0.6 and 0.75, you already have a good "granny" gear. (My lowest, 0.71, gets me up all but the most insanely steep hills.)
If the result is greater than .80 or .90, it may be possible to improve the gearing. If you are new to this, consider visiting your local bicycle store and asking for their opinion about the feasibility of installing lower gears on your bike.
But don't be surprised if you are told, "yes, it can be done, but why would you want to do that?" It is the oft-repeated mantra of bike store staff who know little about touring!
Blackberry
04-16-06, 07:20 PM
You're asking what time it is, and eveyone is telling you how to build a watch. My suggestion: Go to your LBS. Tell them you want the lowest gears you can get. (Maybe that's what you've already got). If that's not the case, maybe they can give you a bigger rear cog or a smaller front cog--or both.
What year is your Giant Sedona comfort bike? If it has 8 sprockets on the rear cassette, it is probably the DX model. The DX model comes with a 28 tooth chainring and a 32 tooth cassette which gives you a .74.
If you have disc brakes, then you most likly have a LX.
My Cypress with similar gearing, is geared much lower than my touring bike.
Most mountain bikes have very low gearing already. Are you planning a very hilly trip?
The lowest you will get for the rear is a tooth count on the biggest cog of 34t and the lowest in the front could be either 22t if you have a 4 bolt crank arm or if you have a 5 bolt crank and you look hard you could find a 20t small chainring. Thats it, no lower. A 22/34 will get you up most any hill if you are in halfway decent shape.
While low gears are something we all have, you still need to work like hell. On the flats or moderate hills there is often a comfortable gear you would happily pedal all day. On hills, with a loaded bike, you often can't find a good spinning gear, and you have a fight on your hand maintaining momentum. Often one looses momentum because of too widely spaced, even if low gears. Point being, keep an eye on the gear spacing as well as how low it is. Some of the gears are ridiculously widely spaced, and the bike slows while you frantically try to catch up with some fast spinning before the whole thing falls over.
Keep in mind that with mountain bike wheels and slicks, you will have lower gearing than even the mountain bike was designed for due to the smaller wheel diameter. You will also have gears designed for the steep choppy hills of-off road, the muddy footing, and the knobby tires. All this means plenty low gears for your avarage on road tour. Enjoy.
BikePackin
04-18-06, 06:02 AM
How do I get some lower gears for my mtn bike. I am planning on touring this summer fully loaded and want the lowest gears I can get. I have a Giant sedona mtn bike that I converted for touring. I have no idea what gears it has. Is this something I can do myself? Where can I get the gears online? How do I know what kind of gears I have and what kind to get.
To get lower gearing, which, for me, was one of my all time best modifications to two of my bikes, I went to a knowledgeable bike shop and had the MegaRange gear sprocket put on both. That was several years ago and I think it was around $50 / bike at that time. The MegaRange has the 34 teeth you have seen referenced in earlier posts.
Also, one earlier post commented that most bike shops will try to convince you not to do this.... I have experienced that as well.... I have, also, arrived at the same conclusion that it is because they do not understand fully loaded touring.....I love not having to work hard when riding thru mountains fully loaded and the MegaRanges do it for me... I even use the lowest range of 22 teeth on my front gearing !
All of this means that you can climb any paved grade made for auto/truck travel in the U.S., as long as you can psychologically zone down to and enjoy (Lots of folks can not) 3.5 mph.
If you have not already heard the term Chain-Inches, you will (synonomous with Gear-Inches). The lower your Chain-Inches the more climbing power. Rough cut arithmetic = (front teeth divided by rear teeth) x tire size = Chain Inches.
Example: (22 divided by 34) times 26 inch tires = 17 Chain Inches. Very few riders have Chain Inches below 20.
See you on the Blue Ridge Parkway !
howsteepisit
04-18-06, 09:28 AM
So as a question for you all, how slow can you go until you start weaving and loose balance? I can only drop to about 4 mph or so. Also, back in the day (Old Fart story coming up), when I was actually in good shap and worked in a bike shop, I toured witha low gear of 40 x 32 (47 inches) and thought it was more than low enough. So thats the kind of advise I tended to give folks in the shop. I was wrong! Now much older, fatter and less fit, I find that I need to go a low as I can and still stay upright on the bike. Remember those kids in the shops tend to be very fit highly enthusiastic cyclists. As such they have no clue about what the restof us can do or want to do with comfort.
cyccommute
04-18-06, 10:56 AM
So as a question for you all, how slow can you go until you start weaving and loose balance? I can only drop to about 4 mph or so. Also, back in the day (Old Fart story coming up), when I was actually in good shap and worked in a bike shop, I toured witha low gear of 40 x 32 (47 inches) and thought it was more than low enough. So thats the kind of advise I tended to give folks in the shop. I was wrong! Now much older, fatter and less fit, I find that I need to go a low as I can and still stay upright on the bike. Remember those kids in the shops tend to be very fit highly enthusiastic cyclists. As such they have no clue about what the restof us can do or want to do with comfort.
That's the main reason I've never listened to the snot nosed kid behind the repair counter at a bike shop - even when I was a snot nosed kid;) Most of them are clueless and think that everyone should be able to turn over a 42/20 gear for a low gear and if they can't then they aren't really cyclists anyway!
Babysaph, the lowest gear combination you can possibly go is a 20 tooth crank wheel (front) and a 34 tooth cassette gear (back). You really do need to get your hands dirty and count the teeth you already have. Bikes come with different gears and we can't tell you what to get if we don't know what you have.
If you look closely and you can see numbers on the cassette gears (back). They are going to be near the outer part of the gear and will have a couple of letters and a number. The outer most gear will probably have a number like 12 or 11. Once you find the number, you should be able to find it in a similar spot for each of the cogs (gears). But these numbers might be obscured if your drivetrain is dirty. You can also count the number of teeth on each cog (for all 8 cogs on the cassette). Since you are only interested in the low gear, you could just count that one (the largest cog on the rear cassette). My guess is that it will be either a 28 tooth, 30 tooth, 32 tooth or 34 tooth cog. If it is a 34 (my best guess is that it is) you can't get a lower gear in the back than that. Any of the others you can change but you will probably have to get a whole cassette to do so.
Now for the front, look at the gears on the front, they should also have a number on them (look on both sides of each gear). If they don't you can count each tooth on each gear. Or, since you only want a lower gear, count the ones on the inner gear (smallest). I suspect that the number you come up with will be either 28 teeth or 22 teeth. You can go lower than this. The smallest you should be able to find is a 20 tooth gear.
After you have the numbers go to a bike shop - buy the stuff from the bike shop and not on-line since they have to pay the bills and advice isn't usually free - and ask them about the parts you need. If the snot nosed kid behind the counter says it can't be done, find another bike shop or find an older mechanic ;) It's a fairly easy replacement for both the cassette and crank (if the gears on the crank can be replaced. Some can't).
If you want to read more about cassettes and gearing go to Sheldon Brown. Cassettes are here (http://sheldonbrown.com/k7.html) and how to figure out your gears is here (http://sheldonbrown.com/gears/). While you are there take a look at how all this stuff works together here (http://sheldonbrown.com/gears.html).
babysaph
04-18-06, 11:04 AM
How is 28 divided by 32 equal .74?
roadfix
04-18-06, 11:15 AM
How is 28 divided by 32 equal .74?
Never mind the fuzzy math.........you still haven't told us what gearing you have.
cyccommute
04-18-06, 11:23 AM
How is 28 divided by 32 equal .74?
Now multiply it by the wheel diameter. In your case use 26.5 (pretty close). That gives a "gear inch" of 23" (28/32= 0.875 by the way). Gear inches comes from the days of the Ordinary (big wheel bike). If you were to attach a crank directly to the axle of the wheel (like a tricycle), you'd be pedalling the equivalent of that diameter of wheel. The smaller the gear inch the smaller the equivalent wheel.
23 gear inches is low but you could go lower. For example a 22/34 gives 17 gear inches. A 20/34 gives 16 gear inches. Those are the lowest you can go with your bike (if you had 24" wheels or 20" wheels you could go lower but...). If you are climbing a huge hill with a load, a 17"gear can make the difference between riding to the top and walking. I hate to walk so I have gears in that range on nearly all my bikes. I don't use them all the time (and you won't either) but it's nice to have them...especially on an absolutely hideous hill like the Alpowa Summit in Eastern Washington :o
babysaph
04-18-06, 01:30 PM
Someone above mentioned 28-32 gears. That is where I got that number. By the way that is my gearing as well.
roadfix
04-18-06, 01:58 PM
Someone above mentioned 28-32 gears. That is where I got that number. By the way that is my gearing as well.
You most likely have 110/74 cranks. You can swap your 28 granny for a 24 and change your cassette to one with a 34 big cog on it. Those changes will yield a noticable drop.
If you need an even smaller granny, you need new cranks.
Lolly Pop
04-18-06, 02:12 PM
I love my new low gearing. I described the process in a thread a few weeks ago.
How is 28 divided by 32 equal .74?
It doesn't. Probably human error with the calculator.
It would have been more fun to edit my post though.
The 34 tooth Mega-range makes a difference in hill climbing ability. It takes a little getting used to though. The first few times I tried downshiftting to it while climbing a hill without my feet clipped in was an experience. You should get used to it quickly and really enjoy the climbs.
Recycle
05-19-06, 03:19 PM
Did babysaph ever change gearing on that Giant Sedona, and if so, how is it working??
I want a lower granny gear on my Giant Cypress DX, which is the road version (700x40C tires) of the Sedona (26x1.96 tires). The bikes have the same gears … a 28/38/48 chain ring with an 11-12-14-16-18-21-26-32 cassette
The fastest, easiest, least costly option for me seems to be to change to a 22/32/44 chain ring. That lowers the granny gear to 18 gear inches (from 23). I loose the highest gear ( drops a 116 gi, leaving 107 gi at the top), and I loose one other mid range gear to duplication.
The LBS sez the Cypress shifters and derailleurs will handle the conversion
Looks like a good tradeoff for me.
Monoborracho
05-19-06, 10:10 PM
I'm an old fat man and my 28-38-48 cranks with a 14-34tooth megarange on back transforms me into Super Billy Goat with 90 pounds of bike and bags. I've never had to walk a hill. Took me a while to spin my way up a few, but haven't walked yet.
BikePackin
05-22-06, 07:48 AM
Just returned from doing another section of the Blue Ridge Parkway... would never have been able to enjoyably pull the 6%+ grades without the MegaRange gear ring (mentioned in earlier post).
Ben There
05-22-06, 08:50 AM
After you've maxed out gearing with smallest on front, largest on back...
If you still wish for lower "gearing", you should investigate Longer crank arms.
Longer Crank arms can improve your overall mechanical advantage.
ie: going from 165mm cranks to 175mm cranks will increase low end torque by 6%.
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