Best practice with Sunrace Thumbshifters

[Berkeleyan]

Brief background, my wife's 1995 B'Stone X0-5 thumb shifters died after a mild crash. I replaced them with the beautiful Sunrace thumbies from the mothership website. Now she complains...

She has Dove bars (like Albatross but more straight-back at the grips) and cork grips, and she was used to the old shifters being closer to her hands than I can get the Sunracers, when mounted in the "outer" position. She tried them mounted as "inner" shifters but couldn't get the knack of using thumbs to press down and finger to left back up. I also think the shifters are further away from the bar than she was used to, and have a longer swing.

When mounted outboard, is there a trick to get less cable pulled so the swing of the shifter is a shorter arc? Maybe that's all about mechanical advantage at the derailer. I'm wondering if anyone else has worked through all the permutations of the "outsider" mounting to find a best way.

- Andrew, Berkeley

[Bill Lindsay]

The way to get more cable pull out of a given shifter is to increase the barrel diameter.  That's not straightforward.  If she hates the location as well, it's worth deciding if she wants a different shifter with a larger barrel diameter.  

The way to get more derailleur motion out of a fixed quantity of cable pull from the shifter would be to try alternative cable routing.  Try running the cable on the other side of the anchor bolt and see what that does for you.  JTEK cable rate multipliers may be fruitful, but ideally you'd find somebody who would let you try a JTEK out for free and buy it only if you like the results.  Otherwise that could get speedy.  

Bill Lindsay

El Cerrito, CA

[Joe Bernard]

Andrew, 

I have one each SunRace shifter and Silver2 to compare. The barrels appear to be the same diameter but the SunRace is notably further from the bar, and the lever is a smidge longer. Both distance issues are going to create the sensation that she's reaching further and pulling the lever through a longer arc than the Silver. Does this mean the Silver shifter is more like the one that was on her bike? I don't know but my guess..yes!*

*Assuming we're talking friction shifters here. I'm no help if she's using index.  

Joe Bernard 

On Wednesday, February 7, 2024 at 9:06:00 AM UTC-8 Berkeleyan wrote:

[Berkeleyan]

Joe, yes, she's also a pure friction shifter. I'm looking into how I can increase the diameter of the barrel OR gain leverage on the ancient front Derailer. And honestly folks, I get that these are ideal for "inside" mounting to use both thumb and fingers to achieve the full swing of the lever. If it were just me, would not be an issue. But her muscle memory is brittle in that way.

- Andrew, Berkeley

[R. Alexis]

Hello Andrew,

What shifters did she have on the bike before? When you said the shifters died, what happened? Lever actually break? Was wondering if there was a way to make the old shifters still work. 

Shop I frequent replaced some old Shimano brifters that had thumb shifters. The 4 anchors nubs broke on the shifter mounting. Looked at how to make it work. I initially was able to drill out recesses where the mounting, anchor nubs used to be and tried using the smallest ball bearing to hold it in place. The shifter ended up sitting a little too tall on the mount. Ended up cutting small pieces of a broken spoke to fit in the closed recess of the mount and protrude into the drilled out recess. Once remounted this helped to anchor the shifter body and work again. 

Thanks,

Reginald Alexis