Bicycle Mechanics - 1985 Schwinn Tempo gear question
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My wife's Tempo is a double, is it possible to make it a triple? as she has alot of trouble on hills, and would also like to change the tall ratio for more flat road speed.
Thanks for any input :)
08-10-10, 02:34 PM
The problem here is "possible." Sure, it's possible, but would entail an entire crankset (BB + crankarms/chainwheels) plus a front derailleur and rear derailleur (front to handle the triple chainwheels, rear for a longer pulley cage to wrap the chain in lower gears). Better to sell the bike and buy a good new or used triple.
Changing the tall ratio will not give her more flat road speed. Only training will do that. Higher gears take more effort to push at the same rpm's, especially as you are not only increasing speed but also wind resistance.
There-in lies my "problem" My wife got this bike at a yard sale, it was an nasty, greasy, chipped up, black bike that she thought "had potential" :)
So, i did a re-build on it, sandblasted, painted, etc. and now she thinks it's the "greatest bike in the world" and wouldn't part with it for ANY reason. which brings me to ask these questions --- gotta keep my baby happy :) I guess what I really need to find out is, how does one figure out the crank/gears/derailleur etc. that will actually "fit" this particular bike (here's a picture of the finished product) as, heck -- I've went this far, what's a little bit more going to hurt.
08-10-10, 04:46 PM
triple is crankset and BB , then different RD to take up slack in the difference between the big one and the little one
Then there is adding a wider range set of gears on the back , not more gears, just a bigger difference between the small and a larger low gear.
Supply More data .. how far are the rear dropouts apart?
[drop the wheel and measure inside width]
is it a screw on freewheel hub?
08-10-10, 05:04 PM
I looked at the spec page for that bike, and it didn't mention what the chainring sizes are, but I'd guess 42/52. Couldn't you just swap in a 38 tooth small ring without having to do anything else?
It would be a significant (but not huge) difference and would be cheap and easy. Also what earlier posters said about fitness.
08-10-10, 05:32 PM
what is the drive train? I suspect you might be able to score an nice crankset on the ISO/trade forums a shimano BB to fit said crank is about $30ish and likewise F+R derailleurs can likely be had cheaply.
08-10-10, 06:23 PM
Here's a compromise. Try putting a freewheel or cassette with a 34 tooth granny in the back. You'll need to get a new rear derailleur with a longer cage most likely. See if that is enough for her to climb the hills. If it isn't then stick to the original plan by swapping out the crankset, bottom bracket, derailleurs.
08-10-10, 06:28 PM
Nice looking bike by the way, you did a good job. what kind of paint did you use? how did you create the decals for the downtube. Also, you should fix the position of the quick release. It should be set at a 3 o'clock position to avoid catching it on anything.
08-10-10, 07:43 PM
OR...compact plus corncob. Don't know what components came on the '85, but my '88 has SHimano 105. You can get a SHimano 600 corncob freewheel pretty cheap- like a 12/17, and then use a 50/34 compact crank and BB (Wheel and Sprocket on eBay has them for under $50 including the BB). 50/12 ought to be good for top speed once she gets her cadence going, and the 34 will be easier on the hills.
Compact crankset. Sometimes you can make your own pretty easily. I took a couple of chain rings off a MTB triple (donor bike) and mounted them on my road double, and instant compact crank.
That is what I have on my 1984 Lotus Classique right now. Fortunately it had a crankset with 110 BCD spacing, which made it really easy (and free).
This is my Lotus with my two favorite thrifty changes to make the bike more rideable: aero brake levers and a compact crank. (The aero levers came from another donor bike.)
08-11-10, 09:57 AM
50/12 ought to be good for top speed once she gets her cadence going, and the 34 will be easier on the hills.
A 34/17 is a 54 inch gear. Even if the bike came with only a 24 tooth large freewheel cog that is a HIGHER low gear. A triple should work well with the original freewheel.
08-11-10, 11:50 AM
Good point, please forgive my bad math. A 13/24 FW would work on the bottom end (34/24 is 38.25 GI) but not so great up top (50/13 is 103.8). If she really needs that big of a spread, then it sounds like a triple is in her future...but since you've already put so much work into the bike and she loves it, then the investment would be worth it.
08-11-10, 12:14 PM
There's nothing wrong with a 103.8 top end unless one is heavily attached to pedaling downhil. I raced on a lower top end than that. As for the bottom end there is so much variation in needs according to the rider and terrain it's next to impossible to predict what is low enough. The only good way to tell is to borrow a decently fitting triple equipped bike and see how low she has to go to feel comfortable.
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