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Road bike 1x10 conversion questions

Old 08-02-11, 08:00 AM
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Road bike 1x10 conversion questions

It has become apparent that I will soon need to replace my cassette and probably chain-rings along with my next chain replacement. Since Iím already going to buy Cassette/chain/chain-ring anyway, I think the only additional cost of doing 1 x 10 setup would be a road brake leaver and spacer. Although I generally do my own work on my bike, I am not so savvy when it comes to modifications and knowing what will or not work, so I wanted to run a few things by some people to make sure it will work before I order the parts.

Derailleur/cassette: I donít live in a flat area, but the gearing that I currently have with 59/39, 12-25 has always worked fine and I think I would have a similar range with a 48t chain-ring with an 11-32 cassette. Sram sayís the Apex mid-cage derailleur will work with the cassette. Iím assuming that they recommend that derailleur for use with an 11-32 cassette because the longer pulley cage is able to take up more slack in the chain. With only one chain ring, however, Iím guessing this wonít be a problem because with no small chain ring there shouldnít be as much slack. Would I be able to use my normal short cage 105 derailleur, or is there something special about the Apex derailleur that prevents the pulley wheel from hitting the 32t cog?

Chain line: According to my Google research, I think I should be able to put the 48T chain-ring on the inside of the spider, and use a sprocket spacer https://harriscyclery.net/itemdetails.cfm?ID=836 to move it away from the seat tube by 1.7 mm, positioning the single chain-ring somewhere in between where the 39 and 53T chain-rings would be, hopefully allowing me to use the whole cassette without tweaking the chain excessively.

This is the bike Iíll be ruining: https://www.bikepedia.com/quickbike/B...%203&Type=bike, the drive train is currently in its original configuration. Of course Iíll also need to get a hood/brake leaver to put in the place of the left sifter. Is my reasoning here flawed, or is there something else Iím overlooking?
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Old 08-02-11, 09:40 AM
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I'd only do a 1x 10 i the bike is already a 10 speed cassette, and brifter.

Calculate the Ratios you need I doubt a 12 and a 13 t will be as useful as just one of those .

As a single chairing , using a double crank [withoutchanging the bB spindle ]
neither chainring will be in a good chainline,
as both are offset on either side of it.

instead consider just closing up the difference between the 2 chainrings, leave it as a double .

something like a 42/48t perhaps? or the Paris Roubaix folks race on a 46/53
as the course route is pretty flat , and fast is what keeps you at the front.
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Old 08-02-11, 11:28 AM
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The right shifter is 10-speed already, right?

Which rear derailleur is on there now? The Apex RD not only has a longer cage to take up the additional slack, it also has a different upper parallelogram to accommodate the larger cogs (e.g. 32T). You could get lucky with the current one though.

You don't have to replace the left/front brifter if you don't want.

Also, I assume you have 53/39 not 59/39 chainrings currently. If so, then 48 x 11-32 would have about the same range as 53/39 x 12-25. I think the 41mm chainline of the inner chainring position is pretty well-centered on the cassette.

Looking at: https://sheldonbrown.com/cribsheet-spacing.shtml, Shimano (and SRAM) 10-speed cassettes have a total width of 37.2mm. Half of this is 18.6mm. Looking at my bike, the smallest cog is about 4.5mm from the dropout. So, the middle of the cassette is about 23.1mm (18.6+4.5) from the dropout. The center line of the frame is 65mm from the dropout of a 130mm-spaced frame, so the middle of the cassette has a chainline of about 41.9mm (65-23.1).

You can get shorter BMX/single-speed chainring bolts to mount a single chainring on the crank.
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Old 08-02-11, 11:49 AM
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Yes, it’s a 53/39, I don’t know why I typed that 59. I have 10-speed brifters now. I was just thinking about replacing the left one with a road brake leaver because there is a 150g difference between the brifter and brake leaver. I have a 105 derailleur now. If it doesn’t work, I think my best bet will be to use a maybe an SLX 10-speed RD rather than buying an Apex RD and also a scram brifter. Good call on the chainring bolts, I hadn’t thought about that.
Originally Posted by JiveTurkey
The right shifter is 10-speed already, right?

Which rear derailleur is on there now? The Apex RD not only has a longer cage to take up the additional slack, it also has a different upper parallelogram to accommodate the larger cogs (e.g. 32T). You could get lucky with the current one though.

You don't have to replace the left/front brifter if you don't want.

Also, I assume you have 53/39 not 59/39 chainrings currently. If so, then 48 x 11-32 would have about the same range as 53/39 x 12-25. I think the 41mm chainline of the inner chainring position is pretty well-centered on the cassette.

Looking at: https://sheldonbrown.com/cribsheet-spacing.shtml, Shimano (and SRAM) 10-speed cassettes have a total width of 37.2mm. Half of this is 18.6mm. Looking at my bike, the smallest cog is about 4.5mm from the dropout. So, the middle of the cassette is about 23.1mm (18.6+4.5) from the dropout. The center line of the frame is 65mm from the dropout of a 130mm-spaced frame, so the middle of the cassette has a chainline of about 41.9mm (65-23.1).

You can get shorter BMX/single-speed chainring bolts to mount a single chainring on the crank.
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Old 08-02-11, 11:59 AM
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NB, the chainline on a double crank is Between the 2 chainrings,
so either side of that will be further from one end of the cassette nearer the other ..
pick your cross chain error..

A 150g difference is the weight of less than a sandwich .
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Old 08-02-11, 12:11 PM
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According to this: https://www.sheldonbrown.com/chainline.html I can use a spacer to move everything over 1.7 mm, assuming the space between the two is 5 mm, it wouldn't be exactly halfway between the two, but I think it would still avoid cross-chain issues
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Old 08-02-11, 12:53 PM
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I'm looking at my 2x10 road bike now. With the chain on the inner chainring and 5th largest cog, the chain is pretty damn straight. Just because the the chainline of a double is 43.5mm doesn't mean that's the center-line of the cassette. Again, I calculated it out to about 42mm. This is why the inner chainring (41mm) has a wider range on the cassette than the outer chainring (46mm).

Regarding changing the chainlines, OP, you might not be able to do that depending on the crank/BB system you have. Again, though, you probably don't need to anyway.

If you have a Shimano shifters and derailleurs, don't mess with SRAM. Just get a 9-speed Shimano MTB rear derailleur since it will be compatible with the rear shifter. NOTE: You CANNOT use a 10-speed Shimano MTB RD. I know, it's counter-intuitive, but modern indexed Shimano RDs and shifters adhere to the same cable pull ratio except old Dura Ace and 10-speed MTB. Aside from these, the RD doesn't care how many gears you have; it just goes where the shifter tells it to. You can get a GS (short/mid-cage) MTB RD if you want. I would stay away from "Shadow" (due to the cable-routing) and Rapid-Rise/Low-Normal (due the shifting being backwards).

If I were doing this, I'd get an 11-32 10-speed Shimano XT cassette, Shimano MTB GS RD (Top Normal and non-Shadow like a good ol' Deore), 10-speed chain, 48T single-speed chainring in 130 BCD, and five BMX chainring bolts. I'd hold off on replacing the front brake lever to spread out the purchases and to see if I really felt the need for it.
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Old 08-02-11, 02:13 PM
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Really... I can just throw a 9-speed Shimano mountain derailleur in with a 10-speed road shifter and 10 speed cassette. That is fantastic because I happen to have an Deore 9-speed in my garage. I'll give it a try without the spacer... this may be easier than I thought.
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