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converting downtube to STI(19 posts)

converting downtube to STIcapt pearl
Aug 21, 2003 11:00 AM
I've got a hand-me-down GT Force with 7 speed RX100 and it's been built up pretty light. I'm digging the speed (am usually on a mountain bike) but absolutely HATE the downtube shifters.

What does it cost and is it worth it to convert to STI? I have almost nothing in the bike and I must admit, the former owner went a bit crazy with a spray can or 2 and the aesthetics are a bit wanting. But then again, to jump up to a new complete bike is a lot of green for a man with a baby on the way.

Thanks all,

capt p
could be toughoff roadie
Aug 21, 2003 12:03 PM
I'm not sure you'd be able to find 7 speed STI equipment, and afaik trhe rear hubs for 7 and 8/9 speed are not compatable. They aren't even the same width, so an Aluminum frame may be stuck with 7 speed, or maybe "8 out of 9 on 7" gearing (running 8 cogs from a 9 speed on a 7 speed freehub).

So the bad news is, you'd be looking at a 8 or 9 speed system, which requires a new rear wheel (hub at least, say $50- $200), new cassette ($25 and up), and new shifter / cables / etc ($100 and up). Oh, AND a new 8/9 speed rear derailuer.

That's the bad news. The good news is that 7 speed bar end shifters should not be TO difficualt to find, and would cost a whole lot less. They work the same as down tube shifters (non ratcheting) but mount in (obviously enough) the ends of the bars. You'd still need new cables, and also some "stops" for the new section of housing that runs from the shifters to your downtube shifter bosses. All total, maybe $50-100 bucks new. Less if you can find a good used deal on e-bay or some such.
bar end shifters?capt pearl
Aug 21, 2003 12:33 PM
Like the tri guys use? Wait, that's brakes. <$100 is a price that has my attention.

Shifters hanging out of the ends of the drops? Heck, sounds a lot easier to reach than the downtube (sux! - how the heck do you change gears and grind up a hill out of the saddle with DT shifters?). But wouldn't they be prone to wreck damage - I mean, if I ever were to wreck, of course, Not that I would or anything. Just hypothetically.

Can you tell I'm more familiar with a mtb?

Thanks,

-capt p
Barcons are LESS prone to crash damage than STI...The Walrus
Aug 21, 2003 1:19 PM
...ask anyone on the cyclocross board. They're light, simple and reliable; not as convenient as STI, but they're a much cheaper way for you to go.

...and there's absolutely
i nothing
wrong with being "stuck" with a 7-sp drivetrain.
OK, so maybe "Barcons" are the way to go...capt pearl
Aug 21, 2003 1:28 PM
...I'm on my way over to the cyclocross board (because I don't have enuff hobbies to be mediocre with!) but do you mind filling me in on what they are, where to get them, and how to set them up.

I have *nothing* against my 7 (14!) gears. Hell, other than the questionable paint, the only thing I don't like about the bike is the downtube shifters. They are just soooo far out of the way when I'm trying to climb (or much of anything else - ever fondle the front wheel instead of the shifter - spooky. I'd rather not repeat.)

Thanks, Walrus,

-capt p
OK, so maybe "Barcons" are the way to go...The Walrus
Aug 21, 2003 7:49 PM
Barcons are simply levers (friction for the left, indexed or friction--your choice--for the right) that are inserted in the ends of drop bars and secured with an expansion bolt (word of caution here--when tightening this bolt, turn
i counterclockwise
; I destroyed one shifter trying to remove it, thinking I was loosening when I was actually irreversibly wedging it in...) You should still be able to get 8-sp models from mail order houses like Nashbar, or find 7- or 8-sp sets on eBay. (8-sp will work fine on a 7-sp cogset; just use the limit screw to keep from shifting past your lowest cog and into the spokes.)

Setup's pretty basic. In fact, the most difficult thing about installing barcons is wrapping the bar to accommodate the cable housing. You can see in the photo that the housing runs along the bottom of the bar
i under the tape
up to the first bend, and then there's a large, exposed loop of housing curving back to the stops on the frame. There's nothing terribly arcane about the process--it just sounds/looks worse than it is.

Oh, just FYI--I just took delivery today of a (used) bike that I got partly because it has (drumroll please!)
i downtube
shifters! Can't wait to try 'em...
gorgeous VooDoocapt pearl
Aug 22, 2003 9:32 AM
I'd love to find a good hardtail VD mountain bike frame.

You wouldn't happen to have a closeup of the BES cable routing, would you. I'm about sold on this idea and have a buddy with an older 8 speed BES he'll let go of.

By the way, when using the downtube shifters on your new-to-you bike, if you feel something spinning fast and your hand gets warm - that's called a "front wheel". Ummm, don't grab.

Thanks for all the help.

-capt p
bar end shifters?dotkaye
Aug 22, 2003 8:58 AM
here's the cheap simple way: buy these bar end shifter mounts from Rivendell for $30, and bolt the existing DT shifters onto these mounts. Some new cable and housing, and you're all set.

http://www.rivendellbicycles.com/webalog/shifters_derailleurs/17068.html

My race bike (triathlon) has barends mounted on the aero bars. When I go mountain climbing, I take off the aero bars and move the shifters to the drops. It works great.
bar end converters?capt pearl
Aug 22, 2003 9:24 AM
Do I understand the concept - these plug in the bar ends, then my existing DT shifters mount to these? Hmmmm .... pretty fiscally doable.

But what about style points? Do I still get the CX/bar end shifter style points?

It's all about the points, Baby!

Thanks.

-capt p
A different perspective.TimA
Aug 21, 2003 12:33 PM
Sounds like you're trying to do this on the cheap, so here's an idea. Check Ebay for some used 7 or 8 speed sti levers. The 8 speed will work on a 7 speed cassette okay. Make sure the front shifter matches your crank. You'll also need cable stops for the frame, usually $10-20 on Ebay. Other than that new cables and housing should do it for you. Here's an auction (not mine) that has all you'll need

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3622821479&category=36140

-Tim
8 speed STI on 7 does not work wellLC
Aug 21, 2003 2:31 PM
The spacing is slightly different and I was not happy no matter how I tried to dial it in. There will always be one end or the other of the cassette that won't be quite in gear.

What you can do is get 9 speed STI, and a 9 speed cassette. use 8 cogs out of the 9 on a 7 speed hub which fits nicely. You will also save money in the long run when you someday get a 8/9 speed (130 mm spaced) frame.
Could be tougherpmf1
Aug 21, 2003 12:35 PM
The axle spacing for a 7-speed frame in 126 mm. Its 130 mm for an 8 or 9 (and 10) speed. If your bike is steel (I have no idea what a GT Force is), you can get a frame maker to spread the rear triangle. If ist aluminium, you can't do it. Another avenue is to simply yank the triangle apart yourself and jam a 130 mm hub/wheel in. I did this with an old Cannondale and some spare 8-speed STI stuff I had several years ago. It worked OK, but not great. The shifting was never 100% and the wheel did not center. After about 2 years, the rear triangle broke and I gladly tossed the frame (I always hated that bike).

If you wanted to do this, you'd need shifters, front and rear derailers, a cassette, a new rear wheel and possibly a new crank and bottom bracket (I have no idea if STI will work with older rings -- I suspect it would though).

You're talking way more than the bike is worth. Save your money and get a new bike down the road.

And as an aside, RX-100 was not bad componentry. basically it was unpainted 105, which was unpolished ultegra at the time.
Dropout spacingRusty Coggs
Aug 21, 2003 1:16 PM
There were plenty of late 7 speed frames that used a compromise dropout spacing of 128mm. Even if aluminum,sticking a 130 hub in thenm is ok.
I broke a frame doing itpmf1
Aug 22, 2003 6:51 AM
The Cannondale 3.0 aluminium frame I did it on eventually broke.

In my previous response, I'd forgotten that there were 7-speed STI set-ups The poster shoud try to find a set of used 7-speed STI shifters.

If it were me, I'd just live with the downtube shifters and get a new bike down the road. The money saved will go a long way towards buying a good condition used bike.
it's always somethingcapt pearl
Aug 21, 2003 1:21 PM
the frame is AL, not bad, good weight, a bit harsh. And paid for. So your definitely right that anything past about $100 would be money to put toward another bike.

If I can't scare up a used 7 speed STI set or make the bar end thing work (not too sure about that one), I'm just gonna "ride it like I stole it" and mash some gears until I'm worthy of a newer ride.

Shame that it's such a financial pain to upgrade sometimes.

Thanks all,

-capt p
re: converting downtube to STIgtx
Aug 21, 2003 12:58 PM
there are 7 speed RX-100 STI levers. Just watch eBay and they'll pop up sooner or later.
There are several RSX 7 speed STI on Ebay now...c722061
Aug 21, 2003 1:05 PM
re: They were RSX 7 speed , not RX-100 7 speed....nmRusty Coggs
Aug 21, 2003 1:12 PM
nm
re: converting downtube to STIGregJ
Aug 21, 2003 5:23 PM
http://www.bikeusa.com/MERCHANT2/merchant.mv?Screen=PROD&Store_Code=MSGI&Product_Code=LD3334

You can get 7-speed STI levers for 91 bucks a pair from Mud, Sweat and Gears at the above URL. They are Sora and I do not know if the spacing is the same as your existing set-up. Make sure you check that out. There is a lot of knowledge on this board to be sure but frequently repeated is the myth that older parts, especially Shimano are not available. A little digging should get you anything you need. Personally, having ridden friction levers for many years, then downtube SIS in both 6 and 7 speed set-ups, I would advise you to continue to ride what you have. If you do start to ride a lot or with groups of riders, you may want to get some STI or look for a more up to date used bike. As far as bar ends go, I think they are a poor substitute for STI, and really if you have to reach down to the drops to shift, how much further is it to the downtube? On loaded touring bikes which can be a little unstable or maybe on a cyclo-cross bike, they could possibly make some sense.