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Old 04-28-06, 07:12 AM   #1
jim p
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I need some advice on an older bike

I found a 1988 model Diamond Centurion at a bike shop. The owner has upgraded the bike with brifters and is asking $275 for the bike. It is a 7 speed with a 26-13 on the rear. I am just starting to ride so I am weak and I need more teeth on the back to climb hills. The owner mountain bikes and bought the bike in 1988 for cross training to help improve his endurance. He said the bike only has 1500 miles on it and new tires. He will also go over the bike and put it in perfect working order and fit it to me. He also suggested that I might want to change from a 7 speed to an 8 speed so that I could get more teeth on the rear. This is also a steel bike and I saw taiwan on the frame.

So here are my questions. Can it be changed to an 8 speed without having to change cranks, chain rings and chain, and also will the rear have to be cold set to accept the 8 speed upgrade? Does this bike have cassets or would it require a different back wheel assembly to change to 8 speed? The guy selling the bike owns the shop, is a bike mechanic and seems to be honest. So I could probably ask him all these questions and get correct answers but I am so new to bikes that I don't know what question that I should be asking. So any help with what to ask would also be appreciated. Also does the price of $275 seem reasonable? Since I have only been riding for about 4 months on an old bike that I fitted as best that I could do I need to let him fit the bike to me as he offered or should I just do the best fit that I can and after I ride longer have him fit it to me?

Thanks for your time and comments.
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Old 04-28-06, 07:49 AM   #2
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Originally Posted by jim p
I found a 1988 model Diamond Centurion at a bike shop. The owner has upgraded the bike with brifters and is asking $275 for the bike. It is a 7 speed with a 26-13 on the rear. I am just starting to ride so I am weak and I need more teeth on the back to climb hills. The owner mountain bikes and bought the bike in 1988 for cross training to help improve his endurance. He said the bike only has 1500 miles on it and new tires. He will also go over the bike and put it in perfect working order and fit it to me. He also suggested that I might want to change from a 7 speed to an 8 speed so that I could get more teeth on the rear. This is also a steel bike and I saw taiwan on the frame.

So here are my questions. Can it be changed to an 8 speed without having to change cranks, chain rings and chain, and also will the rear have to be cold set to accept the 8 speed upgrade? Does this bike have cassets or would it require a different back wheel assembly to change to 8 speed? The guy selling the bike owns the shop, is a bike mechanic and seems to be honest. So I could probably ask him all these questions and get correct answers but I am so new to bikes that I don't know what question that I should be asking. So any help with what to ask would also be appreciated. Also does the price of $275 seem reasonable? Since I have only been riding for about 4 months on an old bike that I fitted as best that I could do I need to let him fit the bike to me as he offered or should I just do the best fit that I can and after I ride longer have him fit it to me?

Thanks for your time and comments.
Depends what you want to bike for. For commuting 7 speed is really hard wearing and good. The important thing is that the frame fits you. You can probably get newer gear on a newer bike for same money, slightly more. Buying something like this needs to be for a custom reason in my opinion. Is it a double or a triple. If you are of a certain age as I am, then if there are much hills around then a triple is good.
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Old 04-28-06, 07:58 AM   #3
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A lot of questions are raised such as: Is this bike a road or mountain bike? What are the names of the components? What model/year is this bike from? Does the bike have a triple crank?
If you have a triple crank, I wouldn't worry to much about switching to an 8 speed cassette. 7 speeds are simpler for now, if you need to you can put a slightly different rear 7 speed cassette on there with a wider range of cogs - maybe one that includes a 32 tooth cog.
Also, just what does his offer of "fitting the bike to you" entail? If it means he's willing to swap different stem lengths and heights, different seatposts or even saddles, and maybe even different crankarm lengths, then the mechanic's offer is a quality one,
If its just a matter of adjusting the seat or handlebar stem a few mm, obviously, you can handle that one. Good luck.
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Old 04-28-06, 08:00 AM   #4
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I just re-read your original posting and see that its a 1988 model. Its kind of old to be paying $275 unless its really high quality or special in some way. Is is a Centurion brand? I'm not familiar with a "Diamond Centurion".
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Old 04-28-06, 08:06 AM   #5
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I think $275 is a bit steep for that bike. I'd expect the typical decent Centurion/Diamondback to be worth $100-$150 or so from a private party. Adding brifters ups the value a bit, I think.

Condition counts for a lot, as well as the level of components on the bike.

Switching to 8-speed probably doesn't make sense. You will probably need to either cold-set the frame or just squeeze it in. The bike may have a cassette or a freewheel, but it doesn't matter because the 7-speed cassette hub ("freehub") won't take an 8-speed cassette. So you'll need a new hub - might as well get a new wheelset. Pretty soon you've replaced everything on the bike except the frame, and the frame, while probably double-butted chromoly, is nothing special.

If the gearing on the bike is insufficient for you, you might check around for a used newer bike with a triple crankset. That will give you the low gears you're after, and in a newer, lighter frame. If you buy from a private party, you can probably get something for not much more $$$ than this Centurion. Try your local bicycle message board or craigslist. You can even go the Ebay route if you're brave.
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Old 04-28-06, 08:09 AM   #6
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Originally Posted by masi61
I just re-read your original posting and see that its a 1988 model. Its kind of old to be paying $275 unless its really high quality or special in some way. Is is a Centurion brand? I'm not familiar with a "Diamond Centurion".
"Diamond Back" was Centurion's mountain bike brand. As their mountain bike sales eclipsed their road bike sales, they started selling the road bikes under the "Diamond Back" ("Diamondback"?) brand. So I'm guessing this is a road bike (it has "brifters") made by that company.
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Old 04-28-06, 08:27 AM   #7
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7 speeds is probably enough...

If you need a wider range, I would suggest a wider range 7 speed cluster rather than an 8, which may or may not have a wider gear range unless you search out a wide range cassette. When the manufacturers increase the number of sprockets it is usually set up to allow smaller changes between gears, not to give you higher or lower gears. For example, it is my understanding that you can currently get a 9 speed cassette with a wider range than is available in 10 speed (at least easily, I seem to recall reading in the forums that someone has a wide range 10 speed if you search).

Also, if the Brifters are not 8 speed, then you will have to replace them using another chunk of money... Seven speeds were made both as freewheels and cassettes, so you will have to ask which is on that specific bike... Either way, to upgrade you may need a new hub/wheel. With the upgrades you would probably be in the price range to buy a new entry level bike with zero miles...

As far as price, I just bought a 1988 Centurion Master Ironman (a fairly nice bike that cost about $800 back then) for just over $100, and it needs nothing but tires. It doesn't have brifters, so add a little for that (actually Brifters do cost a lot, so it MIGHT make the difference to some extent, but not $150+ worth)

If you like the bike the way it is, it may be worth it to you, assuming it is a fairly light lugged steel frame like mine... But, if your intent is to buy it and upgrade (other than minor stuff), you may be better off buying something else.

Although the above may sound negative, do not let it discourage you. If you like it, it fits you, it is reliable and will ride it, I think that any bike is worth $275...

Since it is from an LBS, ask if it includes any free tune-ups. That can make a difference too.

Good luck on your decision.
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Old 04-28-06, 08:50 AM   #8
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Thanks for all the good advice. Since the bike did not really make excite me I think that I will just wait and maybe find something that I know that I want. With my present riding abilities a triple would be good. I need low gearing and not high gearing at this time. My present bike is an old Ross Professional that I got from a thrift store for $9 and with $35 worth of tires it is good to go. It is heavy and the gearing is a little high and the pedals are dept. store type pedals but for me this bike is serving its purpose of letting me get in shape and allowing me to learn about bikes so that maybe I can make some informed decisions later.

I have been reading this forum for about a month or so and maybe I can absorb enough information to become bike educated.

Thanks again.
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