First, what is the frame's dropout spacing ? Most 7-speed downtube shifter frames are 126 or maybe 128mm spacing. For either 8-speed or 9-speed you need 130mm spacing. If the frame is steel it can be spread to 130mm. If you go with index shifting the shifters must match the cassette. At this point in time it may be easier to find 9-speed components. You will probably need to re-build the rear wheel with a new hub and new spokes unless the current hub shell can be replaced. You can probably use the current crankset, chain rings, and both derailleurs but you will need a new chain. You will need to replace the downtube shifters with cable housing bosses. If you buy new Shimano STI shifters they come with new cables and housings.

~Al

 

Converting an 8-speed bike to 9-speed is easy. You need new shifters, cassette, chain and sometimes a new front derailleur and you're good to go.

Converting a 7-speed bike to 8-speed is a big deal because you have rear wheel issues to contend with. However you choose to address the rear wheel issues generates a list of other questions that may or may not be a problem. It's a harder question to answer adequately in just a short post.

 

As I recall...

Converting an 8-speed bike to 9-speed is easy. You need new shifters, cassette, chain and sometimes a new front derailleur and you're good to go.

Converting a 7-speed bike to 8-speed is a big deal because you have rear wheel issues to contend with. However you choose to address the rear wheel issues generates a list of other questions that may or may not be a problem. It's a harder question to answer adequately in just a short post.

Memory is a little foggy but I seem to remember that a 7 speed hub can be upgraded with a 8/9 speed freehub body and longer axle. True? Wheel will have to be redished afterward since the 8/9 freehub is deeper. Fairly simple as I recall.

 

Thanks for the help

Sounds like I got myself into a deeper mess than I budgeted for. I found out that I can get Sora 7 speed STI, so that solves my downtube shifter problem without having to mess with the rear wheel. I can recable & install stops no problem. I'll dive in next week and see how it all goes.

 

Just scored a nice older road bike on Ebay. Its got down tube shifters, and I'd like to convert it to either STI or a flat bar "townie." My memory's getting fuzzy on the spacing specs... is 7 speed a narrower hub than 8? What would be the easiest way to convert this bike to lose the down tube shifters? I'm thinking either of scoring some 8 speed STI shifters on Ebay, or ordering Alivio or other flat bar shifters and using a Scott Liteflite "bullhorn" bar. Any suggestions? Am I going to need a new hub & wheel for the 8 speed cassette? Thanks.

I've used 8 speed STI's(non-Dura Ace) to shift a 7 speed cassette. It works great. The scacing is very close and it works great. You just don't use the extra click. If you want to go with total 8 speed, you need to replace the freehub body with an 8 speed(again, non Dura Ace only).

 

Here's a possibility-you can convert to 8 speed by using 8 cogs of a 9-speed set on an old 7-speed freehub. It will require 9-speed shifters and chain, though.

 

8 out of 9 on 7

Dave_Stohler is right. I just recently did the conversion. I decided that, for safety and function, I wanted STI shifting on my bike. Problem was that it's bonded carbon fiber and only 126mm spacing. I was afraid of spreading the rear to 130mm. I was thinking about retiring the frame, then I found the info I needed on Sheldon Brown's website. He said to take a 9 sp cassette, remove 1 cog, and install the remaining 8 on the 7sp freehub with 9sp shifters. It works. First, I bought an Ultegra 12-25 cassette to see if it would fit with the 14t cog removed, and it did. Then I bought Ultegra STI shifters and a 9sp chain to finish the conversion. I set it up with low gear on the shifter as low on th back, with the wasted shift on the high end. The only issue I have is when shifting from the 13 to the 15, I have to give it a little extra encouragement. The ramps aren't quite right for the normal flawless downshift. I'm may look a different casstette/cog combo's to improve this, but otherwise it works great. I also traded my threaded aluminum fork for a threadless carbon one. I needed a new headset, and threaded isn't very well supported anymore, and the threadless combo was noticably lighter, so I figured what the heck. Overall, the changes made a huge difference in how the bike feels and rides. I'm quite happy with it and most of the new parts can still be transfered to a new frame. Besides you can't put flat bars on a road bike, it just isn't right.

 

Thanks, but...

Thanks for the ideas on converting to [almost] nine speed. If this were going to be my one bike, I'd probably go that route just to get the most modern setup & best working controls. But as it is, I'm desecrating a '92 Bridgestone RB-2 that has downtube shifters. I'm pretty set on using the Sora 7-speed STI, just so I mess with the bike less, and especially since I can get the Sora for $60 or so.