I’ve got a SRAM iMotion 3 speed hub on my wet weather bike, and I love it. The gear ratios are perfect for around town, the cable mechanism exiting the hub is elegant and streamlined, and the entire unit is protected well against the weather.
What I did NOT like about this hub was the shifter you’re forced to use. The only factory option for shifting with this hub is a grip shifter that, although functional, isn’t particularly nice to manipulate and scores a ‘Susan Boyle’ out-of-ten for looks.
A few google searches later it was obvious that this shiftingoversight irked more than just me. Problem was that no one (that I’ve come across) had offered a decent solution beyond a friction shifter.
So here I present my own solution that is so cheap and easy you’ll swear you’ll need an STD check afterwards.
TLDR : hated iMotion3 grip shifter so I made something better
Equipment Required:
Trigger shifter
Allen key
Grinder/dremel/file
Time Required: Approximately two beers
I used an old SRAM X7 shifter because it’s what I had around but any trigger will work, just be careful of the cable pull. Each gear change on the hub requires a cable movement of approximately 5mm. It’s important to note also that the shifts on these hubs are nowhere near as accurate as a derailleur requires, so you’ll have a few millimeters grace which makes this a robust solution for almost any shifter. CHeck out the awesome graphic below that attempts to visualise this idea…
Remove the top cover on the shifter by removing the four 3mm bolts.
Before going further, take note of how the lever engages the shift mechanism. We’re going to remove a tooth from the gear so it’s important to mark it now.
Pull down the shifter until you’ve got the index gear by itself
Use a grinder to remove the appropriate tooth. For this example I removed the 2nd tooth in the shift. This arrangement allowed me to utilise all three gears in the hub easily by making one of my shifting actions effectively a double shift.
With the surface as smooth as possible, reassemble the shifter and test it out. Some cable tensioning will be required, use the barrel adjuster on the shifter to get it right.
this is pretty cool and has me intrigued. i don’t really understand how it works though, is each tooth directly tied to a specific gear? how come only one tooth needs to be ground off then, is the cable pull required on gear one twice that to change to two and three?
it works because there is effectively ‘float’ associated with each gear shift. The hub allows the cable tension to vary by around 2mm either side of the ideal position.
The shifter cable pull does not exactly match that required by the hub, but it is within afew mm. Therefore, by making the double shift we can move our shift position from the effective “low side” of the 1st gear range to the “high side” of the second gear range. With the next single shift taking us into the 3rd gear range. If we break the gear ranges into 3 discrete positions for each gear its easier to visualise.
Starting at position one, the double shift takes us to position 5 or 6 (2nd gear). Then, the next single shift takes us to position 7 or 8.
Don’t know about old 3 speed shifters. Maybe, the x7 was just what I had lying around, as I’m sure many people do.
I doubt normal front shifters will work as the amount of cable moved is much greater
Go see the shimergo thread, I dropped a link to a post with tonsa cable pull details. Will help you narrow down on acceptable shifters. Keep in mind that some systems have varying pull through the range, or varying spacing over the range. usually not enough to worry about though.
A Sachs trigger will not work with a Sturmey-Archer hub, which needs a longer cable pull between the top and middle gear. An old Shimano front-indexing STI shifter also works with a Sachs hub
The newer SRAM hubs which use a clickbox are generally available only with twist shifters that fit flat handlebars. SRAM’s assumption seems to be that performance-oriented bicyclists don’t care to use internal-gear hubs – a bit of a self-fulfilling prophecy. There are various tricks to make the SRAM shifters compatible with drop bars – for example, attaching a mountain bike bar end to the stem. Aftermarket shifters also are reported to be in the works.
