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I have a top of the top tube mounted suntour symmetric friction shifter and im curious if it will have enough pull to pull a 10 speed rear cassette. I have a Suntour ARx rear mech so mechanically that should reach just fine. Its just this odd ball shifter im not sure of. Id like to hopefully figure it out before ordering a 10 speed chain only to find it wont work. The 10 speed rear cassette is modestly spaced...nothing crazy like the newer ones that have HUGE high gears or anything. Just a standard road cassette.

Trying to franken bike this 1984 frameset as a 1x system with the parts on hand. IF 10 speed wont work.....then ill need to order a 7/8/9 cassette and chain for it. I have this 10sp on hand so i thought i might as well ask and try to use it.

HillRider

10-speed cassettes are the same overall width (actually slightly narrower) as 8 and 9-speed cassettes so if the shifter works for 8 and 9-speed it will work for 10. BTW, if you already have the 10-speed cassette, why not just give it a try? Just install it and see if the shifter moves the rear derailleur far enough. You don't need a chain to try it.

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AH good point...i didnt think of that.
Thanks

im also in the process of sorting out a crankset. Ive got a modern sram apex but the arms are 175. Im going to need 170 for my short legs. I have also got a nice set of dura ace 7400 square taper crank arms that will fit the 130bcd narrow wide chain ring i have but not sure what length sealed bb i would need to run that one. IM either hoping to figure that out or stumble across some 170mm sram cranks that will work since i already have the bb for those.

Kontact

There was the 7400 crank and the 7410. 112 and 103mm respectively.

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Thanks....yeah...i might try to get a sealed bb and use the dura ace stuff as its the only other crankarms i have that will fit my 130bcd nw chainring i have. It will look a bit more period correct as well. I see the shimano UN series shows a 113 but not a 112. Im not too sure how much 1mm will matter. I might have to go with the 113 in this case. I fully expect to be in 3 or 4 gears mainly in the rear and nothing at the low or high end of the range unless i run into some long climbs which are scarce around here.

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Well i went with a 113mm UN300. I dont even has the drive side tightend fully down yet and its about to hit this ring on the spindle. The tapers are good and no i did not grease the tapers. IM not sure i have seen a ring like this on the fixed side cup spindle. IM about .25mm from hitting it but im not quite to 28 ft lbs yet. Is this ring something they started putting on the drive side so you dont drive the crank too far on? Seems odd.

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i took it to 28 ft lbs and i think it is just barely touching. The NDS i also took to 28. I think i am good to go. That ring must be a sort of guide for "tight enough" to place the crank in the optimal spot for the rear cassette.

Bill Kapaun

All it did for me was force me to buy a new BB tool because my old one didn't clear the ring.

dedhed

​​​​​​The Suntour Symmetric shifter was a unique and clever piece of engineering from Suntour.
To get the most out of the trim feature, the shifter cables need to be properly adjusted.
1. First, have the right shifter positioned for the smallest cog of the rear wheel.
2. Tension the shifter cable to remove any slack that would cause slow response.
3. Put the right shifter to engage the largest cog of the rear wheel.
4. Place the left shifter for the small chainring, pushed all the way forward.
5. Loosen the FD cable stop bolt, adjust the low trim screw to have no chain/cage contact noise from this low gear position.
6. Now tension the FD cable, remove all slack and tighten the FD cable stop bolt.

Now the auto trim function will provide maximum movement when the right shifter steps to higher gears.

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The answer is no.


Installed a new 10sp chain tonight and it cant pull enough to get into the lowest gear with the limit screwed removed. Dumb.

Also.....that Dura Ace 7400 crankset makes no sense at 113mm. Its very close to the rear stays as it travels around and with a chain installed id say it has 1mm of space between the crank arm at the pedal spindle and the chain as it passes. It would hit the chain with a 112mm. Time to rip all this off and start over. I should have just bought a 9sp cassette and been done with it. Not quite sure what ill do for a crankset yet. I might just try to go with a bit longer sealed bb and the same crankset i guess and run ss. I just thought it might be nice to have a few gears for a change.

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Here is how close the crank arm is to the chain. I have never seen this before. Cranks are not bent nor is the frame. Id suspect the spindle is way too short is the only thing i can come up with.

dedhed

you're surprised a 40 year old 6 speed era shifter isn't compatible with more recent drive line?

Clearance is clearance

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Surprised....no. Ive had the old ratcheting style suntour shifters work fine on bikes of the same era..... and was just curious about this center mounted friction shifter since it was an oddball. Knowing this forum is probably the best one with some of the smartest folks (in more ways than one) i thought it might be worth a post. Again....just thought it would be nice to use what i had laying around if possible.

SurferRosa

Chainrings are mounted on the arm properly?

What does the chainline measure from the middle of the seat tube? Usually, it's 43-45mm.

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It measures 45mm. I just checked it. The chainring is a 42t Woof Tooth Narrow Wide and its mounted to the outside. The chainring itself sits flush with the crankset recess so its not like its thicker. I might need to move teh whole thing to the inside mount point from the outside. This will look odd but will give me a few more mm of clearance from the crankarm to the chain itself. I cant explain why that would matter. This is a double and at some point with 2 rings on it the outer would have had to have been this close. Perhaps with 2 rings the outside ring was large enough it kept the chain up and out of the way more. That really doesnt make sense though as it being higher or on more teeth doesnt affect its lateral distance from the arm itself. I wish i had another 130 bcd square taper crank arm i could try out. Ill have to dig tonight and see what else i have that might work.

79pmooney

What is the bike (and year)? What is the crankset? In the '80s, cassettes went to 130 OLD from 126 or narrower and index with its wider FD cages. Quickly chains on the large-small gear combo moved out and cranksets were made wider to accommodate chain and FD. In the "old days", 1970s when I raced, we considered cranks that just missed the chains running over the much narrower freewheels a good thing. (And contact between the two was never more than a simple brush, a little loss of anodizing.)

I've watched crank arms going outboard the past 35 years. I have knees that need low Q-factors (width between the outside faces of the cranks at the pedals). Many of the current cranksets are unrideable for me if I want to keep my OEM knees. Cranks like yours I drool over. If your cranks are 175s and this isn't OK for you, I'll take them off your hands in a flash! (My best bike now sports a crankset made to the ancient wide 3/32" chain standards with a mismatch of 9-speed rings and home-made ramps to keep the chain from falling into the gap. All to get clearances like yours.

Now the very high end race cranksets are returning to the low Q-factors of my racing days. I find this encouraging but I doubt it is going to trickle down. Huge Qs mean cranksets that can go onto any frame by assemblers with little training, knowledge or care.

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The bike itself is a 1984 Lotus Classique

The hope was to run some DA 7400 cranks which i think were around the early 90s with its bb being a sealed but correct length 113 shimano un300. A longer spindle in this case wouldnt push the crankarm away from the chain. That point is fixed.

I am guessing that the 10sp rear cassette is just that much more compact and running the smallest cog is just that close to the chain. If i run it up to the middle of the rear cassette it looks a bit more normal. I was thinking maybe a 8 or 9 speed cassette would be more favorably spaced and give a bit more room. Truth be told ill probably never be in that small rear cog anyway. Same for the largest rear cog.

Kontact

There is not enough good information out there about Dura Ace. You may have one of two spindle problems:
1.Your BB is symmetric and the crank was designed for an asymmetric spindle. Easy to tell if you mount both crankarms and look at the chainstay clearance. Or,
2. The 7400 crank was designed for use with a Campy tapered spindle. This was done with other Japanese pro level components.

You didn't say if the problem with your shifting set up is the derailleur or the shifters. Derailleurs can definitely prevent the a 10 speed range. Does the ARX shift by hand through the whole range? If not, get a more modern Suntour RD.

dedhed

JIS
​​​​​​https://velobase.com/ViewComponent.a...3964a&Enum=115

Kontact

Velobase is built by members, not from industry data. There are plenty of errors on that site, and almost no one knows how to tell a Campy spindle from a JIS by measuring.

So I would regard that information with suspicion.

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Yeah after staring at it a bit more id suspect the ARx rear cant move far enough inward. I have the limit screw removed and it wont by hand. I think common sense would say to try another rear mech here if i want that last large cog...and i do or its going to bug me. I will see what i have in the parts bin to replace it with. I think ive got a 105 laying around here somewhere.

The crankset clears the chainstay equally on both sides. I will measure to be sure. I know its farily close on each side. I can only get about a half a finger width in there which is a bit closer than i am used to seeing but that might be normal in this case.

dedhed

In the comments on Velobase. Real life
"I have read that these cranks can be used with a campagnolo nuovo/super record bottom bracket and experimented to see if this was true and found it was not. The Dura Ace 7400 crank bottoms out on the campagnolo record spindle and after a few 100 miles of riding, comes loose. The campagnolo record crankset however will work on the bb7400 bottom bracket but will sit out further than it does on the campagnolo bottom bracket and effect the chainline."

Also real life users.

Shimano FC-7400 vs 7402 vs 7410 and bottom brackets

Kontact

Maybe there is no problem. Q factor has gotten much larger since 7400 - maybe they just built if for minimal clearance. If it isn't rubbing, it isn't rubbing. Run it.

Kontact

I had missed the comments at the bottom of the page. Thank you for the correction.

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Update.....yup..i found a Ultegra RD-6600 short cage in the parts bin. I threw that on and the range of it is more than enough to get me that last gear. IM all set now. I still question how close the chain is to the crankset when passing by but thats only in the smallest 12t gear which i will probably spend little to no time in at all so its probably never going to be an issue.

Thanks everyone! I cant wait to take this out for its first ride in this configuration, tweak what is needed and get the bars wrapped.