2x7 speed sti compatibility
 

Hey yall, this is my first post so i hope its not too newbish. anyway i've got an old 12 speed Cerria road bike from the 70's. I'm a college kid so thats all I can really afford. Anyway i've got 7 speed stem shifters on it right now where i've tensioned out the 7th gear. I've got a Shimano 105 RD1050 on the back and a a Shimano FD1050 on the front. i've got several questions.
1. Is the front derailleur index compatible, thats the first major question because I'm running friction on the front mech and i cant find any info on if it will index.
2. I'm thinking of putting a 7 speed freewheel on the back and i know that most that are produced now have a "MEGA Gear". What is the normal spread of teeth for a 7 speed freewheel of that era? or would it be better to just run my 6 gear and tension out the 7th gear again.
3. Finally what would be the best set up, I could buy a set of 2x7 Shimano tourny sti's from amazon for about 80 bucks or should i wait for a better deal on ebay?

Thanks in advance!

The front derailleur is friction only on a 6, 7, or 8 speed STI shifter set. If you are strapped for cash, stay with downtube shifters or stem shifters, as they are much more reliable and lower maintenance than any brifter model.

If you must spend money, upgrade the rear wheel to a 7-speed cassette model. You can get corn cob or stepped cassette. A couple of common ratios are 12-26 and 14-28. With cassettes you can mix and match the individual cogs by buying two or more cassettes that have the cogs you want and simply assembling a cassette.

Your front and rear derailleurs should work with the Tourney STI levers. A 14 to 28 freewheel would be the biggest recommended for the 105 RD.

I think the amazon price is great for a set of brifters, a 7 speed freewheel will probably mean a spacer and spreading the rear triangle a little. I like the RSX100, though older and more expensive than the Tourneys they look far better.

One can often change around the rear spacers, and perhaps dish the rear wheel to achieve 7s.

The highest gearing freewheel commonly available is the DNP Epoch, which starts with an 11T cog.

Many of the 70's and 80's model bikes would have been standard with the 12T or 13T as the smallest rear sprocket.

$80 is a lot of money to invest in an old bike. I'd hunt around for a pair of 7 speed downtube shifters. You can find them in a bike co-op; a bike shop might have an old pair lying around.

One possible downside in going from 6 to 7 is you might get some chain rub on the seat stay. 7 speed freewheels tend to be a bit wider. You can take care of that with a 1 mm spacing on the axle.

Steve's advice in post no. 3 that you need to pay attention to the rated capacity of the rear derailleur is spot on.

I'd go ahead and buy the 7-speed STI brifters. I've got a set and have used them on three bikes. Right now they're waiting to be mounted on a fourth bike. They're very handy for vintage bike rides because they work with so many vintage frames. However, I'd follow bikemig's advice and obtain downtube 7 speed shifters and keep them in reserve for when you sell the Cerria. I'd remove the 7 speed brifters and mount them on another ride. That's exactly what I'm doing.

Without assumptions or advise, you may want to consider Microshifters. Less money, and appear to have acceptable reputation, so far.

There is a possibility that you may not have to do much to move to ta 7 speed. Check the clearance between the chain on the smallest sprocket and the seat stay. What is more important, is having enough room for the chain to climb the teeth when shifting. Although not a 70's bike, my upgraded 2x6 to 2x7 only required a freewheel change.

6 sprocket block:
[IMG]https://farm4.staticflickr.com/3680/...cc7b4af5_b.jpgP9161258 on Flickr[/IMG]

7 Spd Block:
[IMG]https://farm8.staticflickr.com/7357/...eb1b8f70_b.jpgPA121374 on Flickr[/IMG]

No adjustment made except the RD limit screws.

Hey thanks for all the responses!i've attached a picture similar to sjx's i think i could just swap the freewheel.
The other pic is just cause. So microshifters are a reliable brand? Only reason i would pic those over tourny, is tourny downshifts with the thumb which is kinda meh. Besides that we have established it would be compatible correct (thats the engineer in me lol). also sorry that pic is rotated could not figure out how to unrotate it
.http://bikeforums.net/attachment.php...hmentid=465708 http://bikeforums.net/attachment.php...hmentid=465707

or should i just hold out for dis Cannondale CAAD3 Road Race Bike w/ Slice Carbon

Microshift SB-R472 7 speed STI can be found on aliexpress for less than $60 shipped. Have you measured the width of your rear dropouts or axle? A seven speed 14-28 freewheel would probably fit and they're less than $20 so there isn't a big investment risk. You'll have to put washers on both sides of the axle inside the threaded spacers to recenter the wheel. Alternately you could try to find a used short-freehub wheel at a bicycle co-op, then you'd also have a hollow axle and quick release. There are still a lot of old shimano 105 126mm axle wheels around. I would try that first because bolt-on wheels suck.

Rear droupout size is 126 mm and do you have any suggestions on where to begin to start looking for a 105 126 mm wheel.

126mm is the width of a 6 or 7-speed wheel. There are plenty for sale on Craigslist priced from about $15 and up.

Craigslist is a good place to start. Prices are usually lower than eBay, and you can find a local Seller so you don't pay shipping charges. You also get to actually see the wheel/wheels that you will get, and don't run the risk of buying a piece of junk.

2nd choice would eBay look for a Seller local to you who you can pick the wheel up directly form instead of shipping. The disadvantage here is that you don't get to see it before buying. The risk being that you buy a piece of junk, and the shipping charges (that you eat both ways are more than the wheel is worth).

3rd choice would be eBay, looking for a Seller who offers free shipping, although the auction prices are often higher than auctions where the Seller does not offer free shipping, you won't have to worry about going to pick up or the cost of shipping charges (which can be very high because of the size of box used to ship wheels). Again the danger is that the wheels arrive in less than spectacular condition and you end up eating them or sending them back (on your own dime).

I've bought several sets of wheels off eBay in the past year for less than $50 a set, and they were all good transactions. The set of wheels I paid the most for were a eBay transaction. The wheels were in bad condition when I picked them up (Seller met me 1/2 half, as he was driving this way anyway). The cassette was worn-out and the cones and ball bearings were all pitted.

My best transaction was a CL deal. I got two sets of new Nashbar 700C 8,9,10 speed wheels still in the boxes (that's pairs of wheels), plus some tubes and brake pads for a total of $20. That was the asking price in the CL ad and the Seller was located less than 20 miles away from my house. +I didn't even bother to try to bargain the Seller down after I saw what was included. Just handed him the money, said "Thank you", and loaded my car up.

What that last post meant to say was that my current rear wheel fits in my 126 mm dropout. So i'm thinking i'll buy the 7 speed freewheel or see if my campus bike shop has one and is willing to for my 6 speed freewheel. and if i can fit one on there i guess the next purchase would be the sti's.

I'd think the campus shop can guide you through this. You may have to move spacers around and dish. 105's aren't the only Shimano hubs made for 126/7 speeds, a number of hybrids from the late 80's had generic looking Shimano hubs with a little 7 speed sticker. Maybe they were called CX? I've got one somewhere.

Well if you find it let me know i'm on the prowl on knoxville CL

I recently bought the MicroShift 7s "STI" levers for like $55.

They have both shift levers in front of the handlebar so can be shifted in both directions from the drops!

The base-level Shimano STI levers have a poorly-positioned mickey-mouse ear shift lever that can only be shifted from above, which would seem intended to make a beginning rider stay a beginning rider, instead of embracing the speed of a road bike while shifting in both directions.

What do you think of them? I have a STI build to do over the winter and although there is a pair of 7s Sora levers put away I'd like another option.

Top

I have yet to install them, but they are worlds better than Sora/Tourney with the inaccessible upshift lever.

I've ridden 8s Microshift levers, so can say I like the shape and function, though it takes some time to get used to their different format.