Bicycle Mechanics - Converting 7 speed to 8 or 9 speed

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA
markm109
08-12-04, 03:47 PM
I have a bike with all shimano exage EX300 components and it a 2x7 or 14 speed. The rear wheel needs to be replaced. The rear cog is a cassette. The bike is cro-mo. So as I see it I have several options:

1. Get a new rim and relace the spokes. One nipple is damages and I would have to find a replacement. I have never built a wheel so this option is interesting, even if I screw it up, a lbs can do it. Would it be good to replace the spokes and nipples as well?

2. Buy a built wheel, new or used, put the cassette on it with a spacer and retune the rear derailure.

3. Since a new wheel is 8 or 9 speed and I have a spare 9 speed cassette, replace the rear derailure with a new one (Shimano 105?) and replace the downtube shifters with a 9 speed setup as well. Or will the 7 speed shifters work? I don't think the rear derailure would work, right?

I am thinking about option 2 or 3, but need to learn more to see if option 3 is viable. Does anything else need to be changed? Cables?

The bike is fun to ride, it has a different geometry than my regular bike and the down tube shifters are neat comparted to my other other bike's sti. I ride this bike on days it may rain and on dry days in the winter. I know the bike is barely worth the price of a new wheel, let alone the full option 3, but hey, the wife won't let me buy another bike so all I can do is fix it and upgrade it. Something about already having 3 bikes, why do I need another one? Women can be funny about things sometimes. :D

Any and all (even if you say I'm crazy) opinions are welcome. Thanks in advance for your help.

Mark

Retro Grouch
08-12-04, 05:03 PM
The first thing that I would do is to measure the distance between the rear dropouts. If it happens to be 130mm, go buy a lottery ticket because this is your lucky day. If it's 127.5, go ahead and stick in the 9-speed wheel but skip the lottery ticket.

If it's 125mm, you'll probably have to bend the rear triangle a bit to get the 9-speed wheel to work. There's no need to get too worked up about the bending, it's only a couple of mm on each stay. It's easier to do than you probably imagine. If you want to check the alignment when you are done, hold a straight edge between the head tube and dropout and measure the distance to the seat tube on both sides.

7-speed shifters will probably work in friction mode but they certainly won't index. If you decide to upgrade to 9-speed index shifters, you might find that you have to replace the rear derailleur, but, being a retro grouch and a cheapskate, I'd sure try your current derailleur first.
sydney
08-12-04, 06:28 PM
3. Since a new wheel is 8 or 9 speed and I have a spare 9 speed cassette, replace the rear derailure with a new one (Shimano 105?) and replace the downtube shifters with a 9 speed setup as well. Or will the 7 speed shifters work? I don't think the rear derailure would work, right?



MarkThe RD works. 7 speed shifters ain't gonna index but have a friction mode.If you get 9 speed shifters,they will be DA and will have a sticker saying compatible only wirh DA RD.Ignore it.

sydney
08-12-04, 06:31 PM
The first thing that I would do is to measure the distance between the rear dropouts. If it happens to be 130mm, go buy a lottery ticket because this is your lucky day. If it's 127.5, go ahead and stick in the 9-speed wheel but skip the lottery ticket.

If it's 125mm, you'll probably have to bend the rear triangle a bit to get the 9-speed wheel to work. The numbers for dropout spacaing I have always seen are 128 and 126 for most 7 speed road,although a few may have been made with even 130.