Bicycle Mechanics - Shimano RSX shifter with Suntour FD
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09-03-11, 08:40 PM
So I'm in the process of converting my bike to older STI shifters on my Suntour Edge equipped bike. I'm going to be installing the left RSX brifter soon and was wondering if I'd be running to any problems with the front Suntour dérailleur.
I'll also be needing a cable stop for the left side as well. Does anyone know where I can buy just the left side by itself with a concaved base? Or anyone willing to sell me one for cheap?
09-03-11, 08:56 PM
1. by all means try that shifter/FD combo and see what happens, but don't get too hopeful. For one thing, RSX integrated left shifters have no "overshoot, then drop back" in their cable throw, so if you punch in the shift, the FD is moved precisely to its resting position and that's that. If it's not enough to get the chain to shift, you'll have to re-cock and do another half-a-shift. If it goes too far, you can't trim it back. The RSX stuff expects the chainring shift ramps to do the work, and Edge won't have any. And then there's the question of how far the FD will move, and does that jive with your chainring spacing or not.
2. the local bike shop would probably have some of the cable stops.
09-03-11, 09:54 PM
So in the event the shifter doesn't like the derailleur, would it be the derailleur itself that I'll have to look into changing, or the entire crankset itself?
09-04-11, 04:30 AM
You'd want an RSX derailleur and a crankset with aggressive chain pickup teeth for upshifting. In the bigger picture, I think RSX is a bad direction to try to go.
trdsupragt, I've mated a set of RSX integrated shifters to a SunTour FD. I had to use the off side (commonly called the B position) of the FD's cable clamping bolt to match the pull ratio of the FD to the shifter. No guarantees however.
PS I also used the compact RSX double crankset.
I had bad luck trying to use a Suntour FD with RSX STI. Tried to adjust it, spent a long time on it, then I removed the FD and installed a Shimano RSX FD. Instant success. My personal experience is that front STIs are very sensitive to the model of FD. But maybe its my lack of adequate STI skills.
09-04-11, 11:01 AM
Well it seemed like a good idea at the time, since I got them cheap lol. I have a 7 speed and when I saw the RSX shifters, I thought I'd go for them, and keep the bike a 7 speed. I previously had a Suntour freewheel and knew that they wouldn't slide with the STI's for sure, so I had it converted to a cassette when I got a new wheelset (which I was already looking for). So right now, the backside shifts just fine with a Shimano RX100 RD on it.
It seems like this could end up costing more than it should if things don't go well. I'm not sure I want to pick up a whole new groupset right now either (like Tiagra or 105, etc). But for curiousity's sake, it is possible for me to turn the entire bike into like a 9 or 10 speed system since I've got a freehub on it already? Or are there other factors involved?
7 speed freehub will have 126mm spacing, 8/9/10 speed will have 130mm spacing, unless you installed a 8/9/10 speed wheel with a spacer.
Depends on your bike, on a steel frame, its easy to "squeeze" in a wider rear wheel. You will find a debate on spreading aluminum frame bikes (do a search, I don't want to go there). You are talking 4mm, which is less than 1/4 inch (1/8th inch per side). Steel flexes easily that small amount. I have converted quite a few older bikes to 8/9/10 speed.
Cheapest way to convert a bike, is not the piecemeal approach that you are currently taking (find shifters one place, derailleurs another, wheels a third, etc.), but instead, just find another bike with the components you want, and swap EVERYTHING. Buy right and do the work yourself, and such an upgrade can be completed for free (sell the donor bike later to recoup your investment).
For example, I wanted to upgrade my Schwinn Paramount Series 3, from 7 speed DT RX100, to eight speed STI. So I found a 1995 Fuji Roubaix, 8 speed Shimano 105, all STI. Picked it up for $120. Swapped out everything (including the wheels) with the RX100 bits, so I then had a Paramount Series 3 with 8 speed 105 STI. Rebuilt another frameset with the RX100 bits, and it more than funded the entire swap. (I would have put the RX100 on the Fuji, but someone wanted another bike).
A lot less chance of things not working out, and eliminates the questions about whether this part will work with that part, and so on.
I have done this "donor swap" on many, many bikes.
The beauty of such a swap is that you know everything works together: crank, wheels, cassette, derailleurs, shifters. In my example, since I knew everything worked well on the Fuji, I knew it would work well on the Paramount.
And nothing cheaper than "free".
09-04-11, 11:18 AM
Yeah I already read up on dropout spacing, and I've already got the 130mm freehub on there with a 8/9/10 speed spacer.
I guess I didn't consider the idea of having another bike in my space at the time, since I thought it was a bit of a hassle to try to find another bike again. My thought process is that if I'm looking for a bike with the parts I want, I may as well keep that bike already since it's got what I want on it lol. But I guess I'll see how this thing goes once I slap on the left shifter this week. If it doesn't pan out, then I'll just have to cut my losses and consider a newer bike overall. Learned all this the hard way =[
Converting older bikes is relatively easy, and can be very cost effective. Two of my recent keeper conversions:
1992 Schwinn Paramount Series V, Shimano 600 eight speed STI, mainly Ultegra parts. I just realized that the wheelset and tires below came from that Fuji (parts have a way of moving around bike to bike here):
1987 Schwinn Prologue, it now has nine speed DA. This picture is the prior version, where I had the Ultegra bits that migrated over to the Series 5:
09-04-11, 10:45 PM
fancy looking bikes you got there.. i'm a bit jealous lol.
would a shimano 105 be okay in case i get a new FD? Or would it be best that I try to stick with an RSX FD?
09-08-11, 12:08 AM
Well guys, as we anticipated, the Shimano STI lever doesn't like the Suntour FD. The changing from the small chainring to the large chainring is a bit of a problem because it only goes halfway. And since the lever is a triple, if I try to pull again, it'll go way too far. So I guess I might have to look for a Shimano FD.
As asked in my previous post, would it be best that I stick with an RSX derailleur, or can I use something like a 105 derailleur? The 105's seem easier to source.
09-08-11, 12:55 AM
To leave out a bunch of in-depth explanations why, I think you'll need:
1) the RSX FD (they're top-swing like a mountain FD (http://lh5.ggpht.com/_gaZOL0Gs1CU/TUCaXI4AIII/AAAAAAAAALw/voXn4K6_PUo/s640/DSC_0937.JPG), and I'm pretty sure they use a different actuation ratio, which means the shifter does too), and
2) an outer chainring with very aggressive pickup teeth. Because like I said, RSX has no overshoot-and-then-drop-back in its stroke, as you can see for yourself.
That's a lot of fussing just to get use out of an obsolete, oddball RSX shifter. It is not logical, Captain. You could get some normal-ish Sora 7sp if you're patient and watch Ebay for them. In the meantime, since you have a double crankset that's basically just Low/High, you could continue to run a downtube shifter on that side.
mechBgon, The RSX group is a road group and the double FD I have in the parts bin is bottom swing.
trdsupragt, The 105 FD will be fine. Any of the other road FDs would be fine also. Too bad the B position didn't work. :(
PS I have't mixed a double FD with a triple STI shifter, maybe an issue there? Is your crankset also a double?
09-08-11, 11:14 AM
Well I figured out a way to get it to work. I set the chain to the largest chainring, and pulled the FD out (and used something to space it out and keep it at that position) so it would clear the chain, with the RD also set at the outermost cog. I then pulled the cable into the clamp as tight as I could. This works, but I don't think it's the proper way to do it. So I'm not sure I want to keep it running that way on my bike.
Shifting up to the largest chainring takes a little bit of effort, and I can see that there is quite a bit of tension in the cable when I do shift. And then when I shift back down to the small chainring, it kind of snaps or pops down into place. It sounds a bit scary, and I'm not sure if that's normal. But I can make a video of it, if needed. I should also mention that it's a brand new cable, if that makes any difference.
I have a double crankset, but I was reading all over that the triples will work for double cranksets also.
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