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-   -   Converting down tube shifters to trekking bars on road bike (https://www.bikeforums.net/bicycle-mechanics/985490-converting-down-tube-shifters-trekking-bars-road-bike.html)

DeadGrandpa 12-12-14 11:01 PM

Converting down tube shifters to trekking bars on road bike
 
I bought an 80's vintage Miyata 215 ST road type sport touring bike, 3 x 6 speed with down tube shifters. I want to replace the drop handlebars with trekking (butterfly) bars like my Novara Safari, which has grip shifters. I found these SRAM MRX 21 Speed (3 x 7) Grip Shift on Amazon, Robot Check . I think these will work. However, I have read enough to question whether the mountain bike shifters will operate the original FD on the Miyata, and if there is a preferred brake lever set to operate the cantilever brakes that were also original. Or should I throw caution to the wind and install trigger shifters? If so, which ones? I am not completely committed to a relationship with the grip twisting shift. My apologies for asking stupid questions.

A10K 12-13-14 12:55 AM

If you have Shimamo downtube shifters now, these will allow you to reuse them on your new bars: Thumbies from Paul Component Engineering
Those shifters are unlikely to work with your current drivetrain. A seven speed index shifter will not properly shift across a six speed freewheel. You could replace you freewheel with a seven speed model, but those MRX shifters are truly bottom-of-the-barrel components anyways.

DeadGrandpa 12-13-14 06:29 AM


Originally Posted by A10K (Post 17385541)
If you have Shimamo downtube shifters now, these will allow you to reuse them on your new bars: Thumbies from Paul Component Engineering
Those shifters are unlikely to work with your current drivetrain. A seven speed index shifter will not properly shift across a six speed freewheel. You could replace you freewheel with a seven speed model, but those MRX shifters are truly bottom-of-the-barrel components anyways.

Thanks for the tip. I never would have guessed a 7 speed shifter wouldn't work, since my Safari came with a 10 speed shifter on a 9 speed cassette, and it works great - except that the last position won't get me that 10th cog. It has a SRAM Attack grip twists which feel cheap like they are about to come apart, but they work fine. I was actually interested in trigger or some non-twisting mechanism.

dynaryder 12-13-14 07:06 PM

SRAM and Shimano have different pull ratios for their rear derailleurs,so the shifters must match. SRAM makes shifters for both,Shimano only makes shifters for their stuff. If your bike has Shimano derailleurs,you need Shimano-compatible shifters. There are other companies like Microshift and Sunrace that also make Shimano-compatible twistys.


Originally Posted by DeadGrandpa (Post 17385709)
since my Safari came with a 10 speed shifter on a 9 speed cassette, and it works great - except that the last position won't get me that 10th cog.

Wat? That shouldn't be,the shifters should match the rear cluster(there are double/triple compatible front shifters). I ditched the twistys on my Safari for SRAM Attack triggers a week after I bought it. 10k+ miles in all weather and zero issues.

Eric S. 12-13-14 07:27 PM

If you find that you need a new rear derailleur to pull this off, a SRAM X3 derailleur is dirt cheap on eBay (~$20.00) and works well. I have one on a flat bar/Grip Shift road bike. The derailleur is huge (long cage only), but works great.

DeadGrandpa 12-13-14 07:43 PM


Originally Posted by dynaryder (Post 17387224)
SRAM and Shimano have different pull ratios for their rear derailleurs,so the shifters must match. SRAM makes shifters for both,Shimano only makes shifters for their stuff. If your bike has Shimano derailleurs,you need Shimano-compatible shifters. There are other companies like Microshift and Sunrace that also make Shimano-compatible twistys.

Wat? That shouldn't be,the shifters should match the rear cluster(there are double/triple compatible front shifters). I ditched the twistys on my Safari for SRAM Attack triggers a week after I bought it. 10k+ miles in all weather and zero issues.

I have read some other threads here and elsewhere discussing trigger shifters vs grip shifters. It seems to be a matter decided by personal experience but I have no experience with trigger shifters. I like the Thumbies suggested by A10K above, except for the price - $74/pair. They do let me use the down tube shifters currently on the bike, though, leaving me only brake levers to match, find and buy. Still, the SRAM right hand twist shifter MRX 6 speed is only $12. The web site says it is made of finest quality materials; they wouldn't lie, would they? I suppose I might find a comparably priced left hand twist shifter and almost be in business if I can avoid ordering the wrong stuff.


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