Converting 1989 or 90 Specialized RockCombo with Shimano 7 sp cassette to touring bike, keeping the 7 sp cassette. I am not interested in friction downtube or bar end shifters and I understand why some tourers prefer them over brifters.

I have bought Shimano ST-2303 triple 8sp brifters, KMZ Z5 chain (116 links, 1/2"x3/32"), Alivio rear derailleur, and have either of two front derailleurs that I can use--Shimano Alivio or Shimano Tiagra triple.

The front crankset now on the bike is a wonderful classic Specialized 110bcd square taper triple crank which I must unfortunately replace because there is not enough room to shift from middle chainring to outer without front derailleur hitting the right spinning arm. Also, I don't believe it would index properly with the brifter.

I would like to keep the smooth spinning square taper bottom bracket if possible.

Questions:
I have found 8 speed triple crankset with square taper--Shimano Alivio. Will this index properly in the front with the brifter and chain I have? Also, which front derailleur will work best indexing with this setup? Rings will be either 22-32-42, or 28-38-48 with the small ring changed to 24t. Will I need to to change the spindle length of the bottom bracket?

I am not totally against having a better crankset and changing the bottom bracket. Will a non-8sp crankset work with the brifters and front derailleurs I have, indexing them properly? If so, what would you recommend? I realize I would probably need a norrower chain.

Are there other considerations I have not addressed to make this a properly shifting tourer with brifters?

Thanks in advance for your advice.

If it was campagnolo what u were talking about the answer is 99% yes... Since you are talking about shimano the answer is "WHO KNOWS" unless u try. The issue with shimano stuff is that some groups dont like to work with other brands, probably it will, probably it wont.

Maybe somebody that is way more familiar with shimano can tell you certainly but you are mixing stuff and shimano brifters and FD's are darn picky with shimano brand.

Thanks for your reply. I, too, hope someone has more familiarity with Shimano as crankset is only component I haven't yet purchased.

The Tiagra F derailleur is compatible with Shimano 8 speed road shifters. The Alivio is not.

9 Speed cranksets generally work fine with 7/8 speed chain. Alivo is a good crankset, though, and will work prefectly with your drivetrain. The tiagra deraileur is likely made for larger chainrings like the 48 and might be tough to get working perfectly (whichis necessary for use with indexed shifting.

Thanks for your reply. As I understand it, you recommend Alivio crank with 28-38-48 rings and Tiagra front derailleur, with possible indexing problems (will have to try to find out).

Can you recommend different front derailleur that would be a better fit than the Tiagra?

Do you believe spindle length will need to be changed or is it too difficult to judge without actually trying?

BS, I also suggest trying the Tiagra FD with whichever crankset you eventually choose as you already have it. While a Shimano road group triple crankset is assured to work with the Sora/Tiagra combo, I'm not positive the Shimano mountain/trekking crankset's chainring spacing is the same. You should be fine with the RD.

Chances are high that when changing cranksets from a double to a triple, a BB with a longer spindle will be required, again this is a test fit item. The Touring Forum is also a good place to ask questions as many there have been through the mix and match drivetrain/shifter builds.

Brad

1. If you're using brifters, go for the Tiagra front derailleur and the 48t big ring. A 42t big ring will look funny and not shift the greatest.

2. Since you haven't bought your crankset yet, ask the seller what BB spindle length it needs. If they tell you something like 110/113, use a 110mm spindle with 130mm dropouts and a 113mm spindle with 135mm dropouts. The test fit criteria is the middle chainring should line up with the middle cassette cog. A millimeter or two off in either direction won't generally be a problem.

Thanks for your reply. Just to be clear, a Specialized triple crank is on the bike now. Good idea to also post in touring forum.

Thanks for your reply. I do have 130mm dropouts. I do prefer 48t big ring. I will be using brifters.

Do you believe that Shimano Alivio crankset will index with brifters and Tiagra front derailleur and proper chainline?

General theme:design of 8th speed was added to 7 speed clusters,
with a similar space between the cogs,
n+1.
after that the spaces get narrower between cogs to get 9th, and so forth,
into a 130 wide hub. and the cogs are beginning to be thinner too..
stick an 8 speed brifter on and give it a go..

Oh you want it to index too .. try it and see..

sideways motion of top/guide pulleys was put in the design ,
to make 'close enough', a margin of error, work.

Good luck with the 8sp brifters; they may work, but I'm dubious.

And, hey -- if they don't work, shoot me a PM, I have a set of RSX 7sp brifters doing nothing....

have you considered keeping original crank and fd?

unless I'm wrong, and I may be, this:https://jtekengineering.com/shiftmate_straight.htm should solve your indexing issues.

Oh man, I missed that part.

I've tried mixing and matching various 7-speed and 8-speed parts over the years. The cassette spacing from Shimano is a hair different so I've never been able to get the indexing to work to my satisfaction for a very long period. The best advice is to make sure it's spot on for the middle cassette cog to minimize the accumulated difference.

Having said that, there are plenty of folks who claim they have made mixed 7 and 8 speed parts index perfectly. Either they're better bike mechanics than I am or they're not as picky as I am.

"...keeping the 7 sp cassette."

Man, I missed this tidbit also! Must be the post Christmas meal stupor.

If the 7S rear has a spacer between the casette and the hub flange that'll make room for an 8S cassette the whole shifter vs. drivetrain becomes iffy. Look for some 7S Sora shifters as the 8S cassette gear spacing is close, but not exactly the same. You may luck out and there'll not be a problem or you may be able to shift fine at one end of the cassette and not the other.

Brad

I'm also under the impression that 8 speed cogs are just slightly narrower than 7 speed, so your 8 speed brifters may not work with the 7 speed cassette spacing.

Thanks for all of your replies. They have been helpful. Bottom line seems to be I just have to try a combination to see if it works.

With an 8 speed shifter, I limited out the highest rear gear (smallest sprocket). So shifting started at second gear, and worked up to 8th. I tried limiting out the lowest (biggest sprocket). The shifter did not like it (smaller paddle didn't seem to have a problem with a missing gear, big paddle did). Note, I have not tried it with a SORA level shifter or below (which is what you have).

You might be able to find a set of NOS or used 7 speed RSX brifters, or a bike with similar. These will index perfectly with a 7 speed cassette and are miles ahead of Sora in quality.

One thing, narrower by 1, the 7 speed cassette driver, in a wheel, of 130 width axle.
will be less dished than making room for the #8 cog requires ..

Were the frame wider, say 135, then that extra 5mm added to the left,
lets the hub be more centered under the rim, further reducing tension differences.

What does this mean?

If I'm interpreting this at all, I don't think the crankset is the issue.

But, the solution to make any 7s freewheel or cassette work with brifters is:
7s Shimano RSX brifters [+ road front derailleur], or
8s Campy Ergo [also + road FD].

+1 I did not understand the crank comment either. Sounds like high limit not set correctly if you are hitting the crank arm with the FD.

Using new STI type FD with older TA Cyclotourist cranks
has been a problem at the best of times ..

though I doubt this is the case, here.

I built up a 85 nashbar sport ex using the stock Shimano 600 FD and crank set, a Deore rear derailleur, and Ultregra 6400 8 speed shifters. Originally I used the original wheel set w/7-speed freewheel and 126 rear spacing, it shifted perfectly. Whe I bought new wheels and spread the rear to 130, I used a NOS 105 8 speed rear derailleur. I have used a tiagra fd to shift Sugino AT triple with 48/38/28 on another build w/ 9-speed Tiagra brifters, Deore RD and it also worked great. It did take some trial and error to get the correct BB spindle length, and rather than buy several BB', I took it to the LBS and they tried several till they found the right length, well worth the cost of the BB and $20 labor.