Tuning SunRace Thumbies

[Bryan Pizzillo]

Hi all,

I was lucky enough to get one of the complete Clems and have been able to put about 250mi on it so far.  Around the middle of December I had a couple of experiences where the chain seemed to slip when peddling and under load.  This is my first friction shifting bike, so I thought it was me.  For the past couple of weeks though, this has become more frequent and has been requiring less of a "load."  By load, it is almost always on a small incline, but I have had it happen while spinning in an easy gear as well.  The most frustrating aspect is that it is (almost) never right after I have shifted, but usually a good 2-3 min after a shift.  You know, just enough that I think it is ok and then bam, I am peddling with no resistance.  Needless to say this is coloring my flirtation with friction shifting and am thinking about going to an indexed 1x11.  

I did do some searching and found similar issues, but not similar reasons (old cassettes and chains), I have:

1. Checked to see if there is a stuck link.  I back pedaled for a while, looking at the derailer and chain and I did not see anything resembling a stuck link.  Then again, I am not a (good) mechanic...
2. Wiped down the chain, cleaned it, reapplied lube... (in hopes that if it was a stuck link or something it would get relubricated)
3. NOT dropped the bike or wrecked it on anything.  The derailer looks pretty straight and does not look bent.

Also, to make things slightly more annoying, I cannot get it to skip when on the bike stand.  I can get it to jump between chains if I do not shift it correctly, but I can't get it to hop off once engaged.  With index shifting, it is usually easy to figure out what I need to do.  It either gets into gear, or it does not and then I can adjust accordingly.  With friction it feels like it probably does not matter much since you move the shifter to get it to the right spot.  With the SunRace though, there is the ratchet mechanism and I wonder if it not allowing the shifter to stay in the position to hold the gear, but instead pulling ever so slightly to get into its, um, "naturally ratcheted position?"  Any suggestions would be appreciated, also any information on how I should set the derailer barrel adjuster and how to set the limits for friction shifting would appreciated.  I looked at things like Sheldon's page, but it seems a lot more geared to index shifting with an aside here or there on friction shifting.

Thanks,

Bryan  

[Belopsky]

I am curious to this as well..on my Hilsen I've noticed this happens and tightening down the shifter screw has helped... (too much tension on the shifter)

[Paul Clifton]

I was wondering about cable tension on friction shifters last night, because I've been thinking of putting downtube shifters on a bike but then I wouldn't have any barrel adjusters, so the tension would have to just be however tight I could pull it. That's seems to bee fine enough most of the time when I set up other types of shifters, but I wonder ....

Are friction shifters less reliant on cable tension, and is it possible to pull the cable too tight when you set up the bike? Is there any reason with friction shifters to tension the shifter cable with a barrel adjuster?

Bryan, this is just a thing I would try but I have no experience that says it'll help, but what about turning you barrel adjusters in to take some tension off, or unscrewing the pinch bolt on the derailer and just tensioning the cable hand tight?

Paul in ATL

[masmojo]

Sorry, I have had similar experience, mostly sorted out now, but a few questions.
What gear set up?
What size bike?
The downside of really long chain stays and long bikes in general is a lack of rigidity, I have little problem with my medium Clementine, it's pretty stout ( considering), but a large might be proportionally longer and the bottom bracket could deflect enough under load to get ghost shifting.
you might check derailleur adjustment, you've done enough miles now that cable stretch & overall seating of housing should be mostly over.
One more thing to check would be the retention ring for the cassette, if it's not tight enough the cassette could be shifting slightly under load.
personally I feel like the Sun race shifters are so nice and I wonder how much it would take for them to just go ahead & make them Shimano index compatible. Or why can't Shimano just make thumb shifters again! My old Deore XT thumb shifters were SO nice! The rapid fire shifters work fine when they are new, but they get sloppy real fast. I am fixing a buddy of mines bike right now because his front shifter is not working properly; he took it to the local mega bike shop & they told him his chain was worn, sold him a new chain & told him his cassette needed changing too! None of that really, just stupid rapid fire shifters.
sorry ranted off topic there! ;-)

[Joe Bernard]

SunRace makes indexing bar-ends you can convert to thumbies. They're called MicroSHIFT.

http://www.microshift.com.tw/BS-A08_Shifters.html

[Bill Lindsay]

If you determine that the clicks are forcing you to put the shifter in a bad intermediate position, I will point out that I've confirmed that a Silver Downtube shifter will work on the Sun Race thumbie base.  That means you could experiment with a "real" friction shifter on that base to see if you get better results.  

Bill Lindsay

El Cerrito, CA

[Bryan Pizzillo]

Hi all,

First, thank you all for your ideas and feedback, the Clem is now shifting/holding gear a *lot* better and any issues with getting to a gear are my own now.  For posterity's sake in case some one does a search in the future, I just wanted to follow up with what I ended up doing.  

To answer some questions, 

• the Clem is the complete-build medium, 52cm.  
• The trouble gears were pretty much in all cogs except for the big and the small, and using the big or small chainring had similar issues.  I do feel like it might have occurred more around the apex of the shifter arc.  Lets say if the big cog is 1 and the little cog is 8, then it was 6,5 and 4.  I don't usually use anything less than 4.    
• Also to note, the issues were not so much on shifting, but riding in a gear for a good ways and then all of a sudden it would skip without warning, usually under load like a hill.  Also it did not skip right when the load increased, oh no, it let me think everything was going to be ok on this hill.  Then bam, a skip and then a fair amount of teeth gnashing and cursing.  Also, the skip did not feel like when you are between two gears, but as if there was no resistance like when have no chain.
  

Anyway, here is what I did:

1. Checked to make sure the cassette was tight.  It was, and I have a new cassette removal tool to boot.  It was tight...
   
2. Put the bike on the stand and tuned it to shift on the clicks like it was indexed.  
1. Rode it for a number of commutes (around 7mi each way) and a separate 10mi ride.  It was better - at least getting it into gear was not as fiddly.  Alas, it was easier to get in gear, and held the gears more often, but would still skip randomly.   Usually only when I was feeling very confident that it would *not* skip because things were going well.
3. Finally, I checked out Bill's SunRace pictures and noted the Ultegra bar ends would fit.  (Thanks Bill!)  I did not know if my issue was me not liking friction shifting in general or just the SunRace, do I did not want to risk the friction-only Silver shifters.  

So now I am running the "front" (left side) Ultegra bar end shifter on the "rear" (right side) SunRace shifter in friction-mode.  Now any issues with shifting seem to be mine alone.  I do get the occasional "slip" but it is that one where it is jumping between two gears, and it still give some resistance when it happens so it is not as jarring.  Once again though, this highlights my inability to get to the gear correctly the first time and a quick trim fixes it.  I am even being bold and shifting on uphills, downshifting and upshifting even.  In the other long thread on the Clem (Clemming Around) there has been some discussion if it is the Altus/SunRace combo that is the issue.  Who knows, but the Ultegra seems to be smoother shifting and does not have the issues.  On the plus side, reusing the SR shifter bases saved $60-70 on a pair of Paul Thumbies. 

Thanks again for the help.

- Bryan  

[Bill Lindsay]

That's great news Bryan.  Are you using the Sun Race shifter for the front derailer?  Or have you installed Shimano barcons on both bases?  

I have a couple project ideas where I might find use for a pair of the Sun Race shifters without the bases.  If you have them just laying around and unloved and want me to offset some of your expenditure for Shimano Barcons, let me know

Bill Lindsay

El Cerrito, CA

[masmojo]

One downside I noticed was the lack of barrel adjusters, this would make fine tuning a little easier.