Sora thumb button breakage -- fix with epoxy?
#1
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Sora thumb button breakage -- fix with epoxy?
My cousin didn't really understand how to operate the Sora thumb buttons on my nearly-unused Burley tandem, and snapped off the left one. I was about to blame the seller of the bike for selling me something that must have clearly had significant plastic fatigue already, but then heard from a mechanic in a bike shop, as well as in other threads on the forums, that this part is fairly prone to breakage. I can't really blame my cousin, since this part really has no excuse for having been engineered in such a way that it would be *that* easy to break.
Now, I know the obvious solution here, since Shimano doesn't sell parts for rebuilding its brifters, is to either replace the whole left brifter with anything that can shift a triple, or to very carefully cobble together the parts from another differently-broken Sora brifter. But I'm nerdy and I'm cheap, so I'd really like to try to see what I can do to plastic-weld it back on. I mean, it was plastic in the first place, so how much force should it really need to take? I suspect that by using a very strong epoxy and "bandaging" the broken joint with the stuff, I probably ought to be able to reinforce it to the point that it might even be stronger than it was to begin with. I'm not averse to filing off a bit of the plastic around the slot between the hood support and the brake lever, to accommodate the thickened thumb lever arm after its plasticky reinforcement is in place. I've also considered the idea of drilling into the remaining part of the arm and attaching an improvised lever to that, but I imagine that would be unlikely to work unless I tried something along the lines of what this guy did: https://bikeforums.net/attachment.php...6&d=1153880455
Actually, I suppose a really cool fix could be to replace the whole plastic part with a piece of metal machined and bent to be an exact replacement, but I don't want to try to undertake that complicated and time-consuming of a fix before at least trying the plastic weld idea.
Anyone here have any suggestions (other than "replace the whole thing", which I am already considering but hate the idea since the rest of the brifter works perfectly well)? Any particular recommendations for epoxy materials to try for the bandaging approach? Any input would be much appreciated.
Now, I know the obvious solution here, since Shimano doesn't sell parts for rebuilding its brifters, is to either replace the whole left brifter with anything that can shift a triple, or to very carefully cobble together the parts from another differently-broken Sora brifter. But I'm nerdy and I'm cheap, so I'd really like to try to see what I can do to plastic-weld it back on. I mean, it was plastic in the first place, so how much force should it really need to take? I suspect that by using a very strong epoxy and "bandaging" the broken joint with the stuff, I probably ought to be able to reinforce it to the point that it might even be stronger than it was to begin with. I'm not averse to filing off a bit of the plastic around the slot between the hood support and the brake lever, to accommodate the thickened thumb lever arm after its plasticky reinforcement is in place. I've also considered the idea of drilling into the remaining part of the arm and attaching an improvised lever to that, but I imagine that would be unlikely to work unless I tried something along the lines of what this guy did: https://bikeforums.net/attachment.php...6&d=1153880455
Actually, I suppose a really cool fix could be to replace the whole plastic part with a piece of metal machined and bent to be an exact replacement, but I don't want to try to undertake that complicated and time-consuming of a fix before at least trying the plastic weld idea.
Anyone here have any suggestions (other than "replace the whole thing", which I am already considering but hate the idea since the rest of the brifter works perfectly well)? Any particular recommendations for epoxy materials to try for the bandaging approach? Any input would be much appreciated.
Last edited by pocky; 07-12-07 at 01:29 PM.
#2
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
When your fall back option is to replace the whole thing, you can afford to mess around with the one that you have because you have nothing to lose other than time.
If your objective is to make the bike rideable, I'd replace the whole thing because that's what I think is going to have to happen anyway.
If your objective is to make the bike rideable, I'd replace the whole thing because that's what I think is going to have to happen anyway.
#3
Death fork? Naaaah!!
Sounds like a job for JB Weld.
Top
Top
__________________
You know it's going to be a good day when the stem and seatpost come right out.
(looking for a picture and not seeing it? Thank the Photobucket fiasco.PM me and I'll link it up.)
You know it's going to be a good day when the stem and seatpost come right out.
(looking for a picture and not seeing it? Thank the Photobucket fiasco.PM me and I'll link it up.)
#4
Senior Member
Join Date: Jan 2006
Location: Camino, CA
Posts: 1,181
Bikes: Trek 5500 OCLV, Trek Fuel EX 9
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Originally Posted by Retro Grouch
If your objective is to make the bike rideable, I'd replace the whole thing because that's what I think is going to have to happen anyway.
#5
Senior Member
Originally Posted by Retro Grouch
When your fall back option is to replace the whole thing, you can afford to mess around with the one that you have because you have nothing to lose other than time.
If your objective is to make the bike rideable, I'd replace the whole thing because that's what I think is going to have to happen anyway.
If your objective is to make the bike rideable, I'd replace the whole thing because that's what I think is going to have to happen anyway.
Why does everyone want to continually dick around when they can just fix the thing and be out riding.
Tim
#6
Hammer Time
Join Date: Mar 2007
Location: Australia
Posts: 258
Bikes: Paconi, Hillman, Sun Tourer + Mongoose Tetra SX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I thought Shimano sold parts.. Why else would they have service and repair info on the website?
#8
Your mom
Join Date: Aug 2006
Posts: 2,544
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I don't think anything's going to stand up to the shear force of pushing the lever down. But hey, give it a shot. Just make sure you're on your middle ring so that you can make it home with a reasonable gear range.
#9
Senior Member
Join Date: Sep 2001
Location: Montreal
Posts: 6,521
Bikes: Peugeot Hybrid, Minelli Hybrid
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
The modification shown in your link was attached to the lever by a piece of safety pin with thread wrapped around, all held together with epoxy. I had to bend the piece of safety pin so it hooked over the inside end of the lever, otherwise it would pull out from the binding. A piece of wire like a paper clip bridging the break will provide all the strength you need to reinforce the epoxy.
#10
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Sora thumb button breakage--compete STI disassembly, epoxy fix, and rebuild
OK, so, this got picked up and put down on and off again for a few months, but last night I finally fixed it. You all should make tremendous fun of me for not just giving up on this, but I'm a tinkerer by trade and this became an obsessive challenge for me. I had a spare MTB front derailleur friction shifter that I could use anyway so this was not going to prevent me from riding the tandem on a long trip (and even so, I didn't really need the derailleur for short trips in super-flat Boston, anyway).
Turns out that this part is actually metal, not plastic as I had assumed earlier--the plastic is only the fused-on button part itself. I tried bridging the break with JB Weld with a bread tie wrapped around it, but the break was too close to the center to make a stong weld (broke again very easily without me reassembling it at all), so I figured I wouldn't get a good enough weld without taking the thing apart to the next level, so I did. At that point I realized I wasn't going to get in there further without taking the pod itself apart, so I did, taking pictures each step of the way for reference, down to the spring-tensioned white "pod" itself, which I left tensioned together with bread ties.
For a stronger brace, I used a metal picture frame hanger (see the very last photo in the last set--I used the 30lb type) which I cut apart at the nail eyelet, and using a small Dremel bit, widened the eyelet into a notch just long and wide enough to actually slip around the joint and provide a firm grip. Using pliers, I then twisted the rest of the frame hanger around the joint up to the remaining metal and that really held it. I covered the whole thing with JB Weld, and once cured, Dremeled it down to give just enough clearance so that it could operate without catching anything. (I erred on the side of leaving just a bit too much, and once the whole thing was fully assembled, I did some hand-filing with precision files just to clear the last places where it was getting in the way.) I wish I had some pictures of this before I epoxied it, but I forgot.
I tried to keep the spring-tensioned parts together, but at some point I slipped and they all exploded in my hand, and I didn't have any pictures to reference that far in. I assembled and disassembled it a couple of times tensioned incorrectly, and gave up again for a while, but last night I picked it up again and got it all figured out. The trick was to catch the big spring in the center in the one place where the pointing part would fit all the way into its deepest groove at the bottom, and then crank it tight by fitting the upper part in and rotating until its notch fit in place. I wasn't sure which of my attempts at this would work, so I stopped taking pictures at this point, but Geoff's site (see below) should be helpful, and along with that, hopefully you can get the idea from the video of the reassembled pod in action. I'm attaching all photos here and to the next posts, and I'll upload the videos somewhere and put in a link.
There's a serious lack of documentation on the insides of STI shifters (surprise, surprise). This guy did a fairly full rebuild with a mountain bike shifter -- https://www.cs.hmc.edu/~geoff/deoredx/index.html -- and a lot of what he says applies, but I found his instructions a bit difficult to translate to the road stuff, so maybe these pictures will be helpful to anyone working on road shifters, and I emailed Geoff to tell him and ask him to put in a link. I feel like I really understand how they work now, and could rebuild one again now with much less trouble.
Full set of photos below, going from the point where the Shimano documentation leaves you hanging out to dry (at https://techdocs.shimano.com/media/te...9830609256.pdf ), to fully disassembled, to fully reassembled.
Turns out that this part is actually metal, not plastic as I had assumed earlier--the plastic is only the fused-on button part itself. I tried bridging the break with JB Weld with a bread tie wrapped around it, but the break was too close to the center to make a stong weld (broke again very easily without me reassembling it at all), so I figured I wouldn't get a good enough weld without taking the thing apart to the next level, so I did. At that point I realized I wasn't going to get in there further without taking the pod itself apart, so I did, taking pictures each step of the way for reference, down to the spring-tensioned white "pod" itself, which I left tensioned together with bread ties.
For a stronger brace, I used a metal picture frame hanger (see the very last photo in the last set--I used the 30lb type) which I cut apart at the nail eyelet, and using a small Dremel bit, widened the eyelet into a notch just long and wide enough to actually slip around the joint and provide a firm grip. Using pliers, I then twisted the rest of the frame hanger around the joint up to the remaining metal and that really held it. I covered the whole thing with JB Weld, and once cured, Dremeled it down to give just enough clearance so that it could operate without catching anything. (I erred on the side of leaving just a bit too much, and once the whole thing was fully assembled, I did some hand-filing with precision files just to clear the last places where it was getting in the way.) I wish I had some pictures of this before I epoxied it, but I forgot.
I tried to keep the spring-tensioned parts together, but at some point I slipped and they all exploded in my hand, and I didn't have any pictures to reference that far in. I assembled and disassembled it a couple of times tensioned incorrectly, and gave up again for a while, but last night I picked it up again and got it all figured out. The trick was to catch the big spring in the center in the one place where the pointing part would fit all the way into its deepest groove at the bottom, and then crank it tight by fitting the upper part in and rotating until its notch fit in place. I wasn't sure which of my attempts at this would work, so I stopped taking pictures at this point, but Geoff's site (see below) should be helpful, and along with that, hopefully you can get the idea from the video of the reassembled pod in action. I'm attaching all photos here and to the next posts, and I'll upload the videos somewhere and put in a link.
There's a serious lack of documentation on the insides of STI shifters (surprise, surprise). This guy did a fairly full rebuild with a mountain bike shifter -- https://www.cs.hmc.edu/~geoff/deoredx/index.html -- and a lot of what he says applies, but I found his instructions a bit difficult to translate to the road stuff, so maybe these pictures will be helpful to anyone working on road shifters, and I emailed Geoff to tell him and ask him to put in a link. I feel like I really understand how they work now, and could rebuild one again now with much less trouble.
Full set of photos below, going from the point where the Shimano documentation leaves you hanging out to dry (at https://techdocs.shimano.com/media/te...9830609256.pdf ), to fully disassembled, to fully reassembled.
Last edited by pocky; 07-13-08 at 11:08 AM.
#11
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
More photos
#12
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Even more photos
#13
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Even even more photos
#14
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Even even even more photos
#15
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Last batch of photos
Last edited by pocky; 07-13-08 at 10:33 AM. Reason: added photo of picture frame hanger
#17
Senior Member
Join Date: Mar 2003
Location: Beaufort, South Carolina, USA and surrounding islands.
Posts: 8,521
Bikes: Cannondale R500, Motobecane Messenger
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
If you replace it, since it is a left brifter, upgrade to Tiagra or better. This may sound a bit foolish with a Sora on the right, but the paddle shifter will handle the stress better. Heck, you can upgrade both to R-500 brifters to maintain the 8-speed.
#19
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
https://www.bikeforums.net/attachment...9&d=1215965392
and it will sense your shifts and tell you what gear you're in.
Here's the instructions from Shimano:
https://bike.shimano.com/media/techdo...9830604501.pdf
Check out chapter 7, on page 16.
Last edited by pocky; 07-13-08 at 06:28 PM.
#20
Senior Member
Thread Starter
Join Date: May 2007
Location: Watertown, MA (Boston)
Posts: 200
Bikes: '00 Kona Yee Ha, '83 Schwinn World (fix), '96 KHS Montana Descent (w/ RS XC-32), '05 Fort Ro.SLC (totaled), '01 Burley Rumba tandem, '15 Mattioli R1, '14 Nashbar Big Ol' Fat Bike, '96 Fuji Marlboro folder (drops), '04 Jamis Satellite, '04 Giant TCX
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I was reminded of this thread today by dnuzzomueller's signature -- https://stiteardown.0sites.net . The step-by-step instructions there are much better organized than my vague descriptions and stream of pictures! It's interesting (but not surprising) to see how many more parts on the old Ultegra are made out of metal as opposed to the plastic on my Sora.
I also decided to search to see if anyone else had done it since, and saw Kimmo's thread: https://www.bikeforums.net/showthread.php/610670
Here's another great set of step-by-step instructions, specifically for Sora:
https://www.instructables.com/id/Serv...Sora-Shifters/
FYI, in spite of what all the haters predicted, my JB-Welded, metal frame hanger-reinforced thumb button repair is still going strong.
I also decided to search to see if anyone else had done it since, and saw Kimmo's thread: https://www.bikeforums.net/showthread.php/610670
Here's another great set of step-by-step instructions, specifically for Sora:
https://www.instructables.com/id/Serv...Sora-Shifters/
FYI, in spite of what all the haters predicted, my JB-Welded, metal frame hanger-reinforced thumb button repair is still going strong.
Last edited by pocky; 07-22-11 at 01:39 PM.
#21
Senior Member
Join Date: Sep 2009
Location: Grayslake, IL
Posts: 53
Bikes: '74 Ral SuperCourse II, '77? Ron Cooper, '82 Scapin Sprint?, '84 Ross Sig, '86 Voyageur, '86 Miy. 512, '87 Prologue, '87 Circuit, '91 MP21, '96? DeBernardi, '14 Dolan Mythos, Giordano Tandem, '18 Masi Alare.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked 1 Time
in
1 Post
Pocky, that was quite a job you did, my hat's off to you. Were it my Sore-ah brifter, he would have been introduced to Mister Hammer.
Thread
Thread Starter
Forum
Replies
Last Post
Beach Comber
Bicycle Mechanics
12
05-24-15 06:55 PM
rustybyker
Bicycle Mechanics
7
08-05-13 06:26 AM