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downtube shifters mounting

Old 01-18-21, 05:02 AM
  #1  
zelenovicb
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downtube shifters mounting

Hi all! Your help is highly appreciated!
I'm about to replace my old Simplex friction shifters with not-so-old Shimano 600 or 105 indexed shifters. locally, I can find only shifters intended for mounting directly on the frame onto a dedicated braze-on. My frame does not have those, so I must install them using a clamp-on (if that's the word). My question is are the braze-on shifters compatible with some/any clamps? I can buy a 600 clamp but can find only 105 or late 600 braze-on shifters, and am not sure if those will fit.
Thanks!!!
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Old 01-18-21, 07:21 AM
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If the clamp has a square shaped shifter mount and 5mm bolt holes, then it will work, assuming the clamp is the correct size for your down tube.
Some of the older shifter clamps, particularly the Shimano ones, have 4.5mm bolt holes that can easily be re-threaded to take a standard 5mm bolt.
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Old 01-18-21, 08:09 AM
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Thanks!!!!
I'll dive in and see where it gets me.
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Old 01-18-21, 09:19 AM
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You might just buy the whole setup cheaper than a mount depending on your application.

https://www.benscycle.com/sunrace-sl...hoC-sUQAvD_BwE
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Old 01-18-21, 10:59 AM
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you'll need a fairly specific clamp-on band shimano shifter if you want indexed shifting. look carefully at the photo: you'll want the one with the notches cut out near the band or clamp - this particular model will allow for newer index 105, 600, dura ace etc if you're patient i found a couple for cheap on ebay



https://www.ebay.com/itm/Shimano-SL-...0AAOSwK~NftW6b
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Old 01-18-21, 08:39 PM
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Originally Posted by rccardr View Post
If the clamp has a square shaped shifter mount and 5mm bolt holes, then it will work, assuming the clamp is the correct size for your down tube.
Some of the older shifter clamps, particularly the Shimano ones, have 4.5mm bolt holes that can easily be re-threaded to take a standard 5mm bolt.
...I would repeat the caveat about the diameter of the clamp you buy. If you are putting these shifters on a frame made of French metric tubing diameter, a lot of the stuff you will see for sale used will not fit. If it's Simplex stuff that ws on some other kind of frame, it might. Measure the diameter of your downtube and shop accordingly.
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Old 01-19-21, 05:00 AM
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You're spot on. I got the same info from a local bike guru: almost no braze-on shifters can be fitted onto a clam without the use of a "bushing" thing brooklyn_bike pointed to. am now officially considering adding braze-ons to the frame... yeeeee more unnecessary work to do on the bike

Last edited by zelenovicb; 01-19-21 at 05:05 AM. Reason: additional info
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Old 01-19-21, 05:09 AM
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[QUOTE=dedhed;21883042]You might just buy the whole setup cheaper than a mount depending on your application.



the shipping costs to eastern Europe would be just to much
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Old 01-19-21, 08:44 AM
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I once dealt with a frame with no brazed on bosses and when the OEM clampon shifters on the DT were replaced with 8 spd variants
in the late '90s I found it expedient to drill a small hole on the bottom side of the DT and thread in a 4-40 sized self tapping
screw to act as a stop to prevent the DT shifters from sliding down the tube under cable tension. This was a steel frame but aluminum
should be no obstacle if clamp on can be found to fit.
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Old 01-19-21, 06:50 PM
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...is there some reason you are averse to using bar end shifters ? If your intention here is to go to indexing, there are plenty of 6,7, and 8 speed indexing barcons bouncing around in the used parts marketplace. Last time I checked, I could still buy 8 speed Shimano indexing barcons new.
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Old 01-20-21, 03:13 AM
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no, no particular reason. But, this seems a cheaper, simpler way to do it. I've never actually seen a bike with bar end shifters (the images on the web don't count ), let alone rode one, so I'm not sure of the feel of it. I'm just guessing, but think the cable routing should be very similar to brifters? do I need cable stops on the downtube?
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Old 01-20-21, 05:13 AM
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never felt comfortable using bar shifters (kids cyclocross)
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Old 01-20-21, 03:48 PM
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Originally Posted by zelenovicb View Post
no, no particular reason. But, this seems a cheaper, simpler way to do it. I've never actually seen a bike with bar end shifters (the images on the web don't count ), let alone rode one, so I'm not sure of the feel of it. I'm just guessing, but think the cable routing should be very similar to brifters? do I need cable stops on the downtube?
...it does require cable stops on the down tube. And somewhere inline, you need an adjuster. But that's usually integral to the rear derailleur, and if you go with a two chainring setup, it's not an issue in front. The cables do route like brifters, but with low friction, lined housing and die drawn cables, you can run the cables all the way up close to the stem, before they exit from under the bar tape.

Downtube shifters are easier and simpler, if your frame is already set up to accommodate them. You were talking about adding braze-ons, which is neither simpler, nor cheaper.

Shimano indexing barcons feel very similar in performance to DT indexing shifters. They just sit in a different place on your bicycle. Cable housing stop clamps are readily available IME.
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Old 01-20-21, 07:11 PM
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I'd be inclined to keep the Simplex shifters, if those are the retrofriction types. I've used a similar design Shimano SL-422 Light Action downtube shifter on my old steel road bike and liked 'em. There's an internal spring setup that appears to be very similar to the exploded diagrams for other retrofriction shifters. It was quite smooth and easy to use, compared with other simple friction shifters -- although friction shifters with micro-click detents are pretty good too.

I've since switched back to the original Suntour GPX Accushift setup, but the friction shifters were more versatile for switching between wheelsets. I use one rear wheel for the indoor trainer, and another for outdoor rides. There's a slight difference in tolerances that hinders crisp shifting on the wheel I use on the indoor trainer, but I don't bother adjusting it since I don't shift much on the trainer.

I also have older Dura Ace indexed downtube shifters, and I think I may have a set from a 600 Tricolor/early Ultegra group. And a couple of Shimano bar-end index shifters, one 8-speed Ultegra, the other 10-speed Dura Ace from a time trial/tri-bike with aero bars. I'm currently using the Shimano 8-speed bar ends on my hybrid with albatross swept bars. Excellent for that use.

A few local friends use bar end shifters on their drop bar road bikes. I'm considering that for one bike but I'll need another set of handlebars. Their bikes are set up for casual riding, with wide drop bars.

One problem I can foresee with bar-end shifters is striking the bar-ends with my knees. I'm tall and skinny and prefer fairly narrow 38cm or 40cm drop bars. However when I stand to pedal up climbs or sprints, my left knee occasionally strikes the bar-end mirror. No big deal, the mirror is on a ball joint so it just moves out of the way and I re-adjust it after sitting to pedal. But that would be disastrous with bar end shifters on climbs or sprints.

So if I decide to try bar end shifters on a drop bar road bike I'll need wider bars, or at least bars flared to 42cm or wider in the drops. Some rando and gravel bike bars would probably do. I could try cutting the ends from one of my current sets of 40cm or 42cm drops and see if it prevents knee strike without compromising handling feel. I also use the drops when standing to climb or sprint, so I'm picky about bike balance and leverage in the drops.
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