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Use a Triple crank to make an Adventure Double

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Use a Triple crank to make an Adventure Double

Old 05-25-20, 01:15 AM
  #1  
Leinster
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Use a Triple crank to make an Adventure Double

I’d like to have a smaller-than-34 inner ring for my road bike, but the Adventure Double cranks that I generally see on the market either don’t fall in my price range, or don’t match the retro-mod look I’m going for right now. But I see some nice square-taper triples on eBay for reasonable prices; is there any reason I couldn’t just take a triple with a 30 or 28 inner ring, put a 44 or 46 in the middle ring slot, and just have no ring on the outer?

Obvious concerns; chain line. When I used to have a triple before, I’d never go into 42x12 to avoid cross-chaining. But now 46x12 will be my highest gear, in the exact same alignment.

Spinning out more; obviously I’d get an 11t cassette next upgrade, and I’ll never top out 46-12 on the flat anyway, but I feel like I’d still be a little undergeared. Don’t take away my 16, though.

Road double derailleur; can it shift into the inner of a triple?

Pros; I feel like I’d just leave it in the 46 most of the time and only use the 30 as a bailout. If I find an ISO triple, I can use my current Chorus BB.

Last edited by Leinster; 05-25-20 at 01:27 AM.
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Old 05-25-20, 03:28 AM
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If you remove the outer chainring and either cut down the mounting bolts or get shorter ones you can then lower a derailleur for double chainrings and have it work. Some people remove the outer chainring and replace it with a pant leg guard.

A lot of 10-sped bikes used to come with a high gear of 52-14 which is @100.4 gear inches.
46-11 is @112.9 gear inches
46-12 is @103.5 gear inches
46-13 is @ 95.5 gear inches

Are you really going to spin out many times in any of those three gear combinations?

You should be able to use all the rear cogs when you're on the middle chainring.

Cheers
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Old 05-25-20, 06:34 PM
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Thanks! Yeah, I have the short chainring bolts from a previous build, so no problem on that score.

I’ve found myself undergeared in 53x14 before, but only when going down the same hills that I want the 30x29 for going up. But you are right, it’s a vanishingly small amount of my riding, so the 46 should cover most bases.
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Old 05-25-20, 09:28 PM
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With regard to chainline, just spend $15 and buy a different bottom bracket.
https://www.ebay.com/itm/Tange-Ln-39...FH4MpzAc8nw7-g
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Old 05-25-20, 10:07 PM
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One popular way to do it is to replace the big ring with a chain guard. Rivendell and others sell "triple" cranks configured this way:

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Old 05-25-20, 10:13 PM
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Check the frame clearance - a 44-46T in the middle slot might touch the chainstay.
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Old 05-25-20, 10:14 PM
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Also check out Raceface Tab Shims. They're for MTB cranksets, so they come in packs of 4, but you could use an old 104/64 BCD triple.

https://www.chainreactioncycles.com/.../rp-prod117551
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Old 05-29-20, 06:24 AM
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I recently performed a similar conversion on a 2001 Specialized Sirius. The bike began with a 52-42-30 triple and 12-25 9 speed cassette. I replaced the middle and inner chainrings with 39-24. I will install the appropriately sized bash guard from https://bbgbashguard.com/ in the outer position when it arrives in the mail.
The old cassette was removed and an 11-32 9 speed cassette was installed.
I lowered the front derailleur as much as I could without interfering with the lower seat tube bottle cage braze-on, and tightened the outer limit screw to prevent the derailleur from moving into the outer position. Finally, a Wolftooth Roadlink (https://www.wolftoothcomponents.com/products/roadlink) was installed to give the rear derailleur clearance for the
32t cog. The 105 long cage derailleur just barely has the capacity to handle the entire range.

In theory, this probably should not work perfectly, but it seems to work just fine even without the bash guard installed. The chain rubs on the larger ring when in the 24:11 position, but this isn’t a ratio one should be using anyway. However I think I could solve this problem with a longer bottom bracket spindle.

My son is planning to ride this on a mountainous road/gravel tour this summer. The original configuration had too many high gears and not nearly low enough gears. Now he has a range of 97-20.5 gear inches.

This photo was taken before installation of the bashguard. Obviously some swapping of shorter chainring bolts was needed to get the pictured configuration to work.
I can update the photo when the bashguard arrives.


Last edited by mihlbach; 05-29-20 at 06:49 AM.
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Old 05-29-20, 06:51 AM
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Originally Posted by mihlbach
I recently performed a similar conversion on a 2001 Specialized Sirius. The bike began with a 52-42-30 triple and 12-25 9 speed cassette. I replaced the middle and inner chainrings with 39-24. I will install the appropriately sized bash guard from https://bbgbashguard.com/ in the outer position when it arrives in the mail.
The old cassette was removed and an 11-32 9 speed cassette was installed.
I lowered the front derailleur as much as I could without interfering with the lower seat tube bottle cage braze-on, and tightened the outer limit screw to prevent the derailleur from moving into the outer position. Finally, a Wolftooth Roadlink (https://www.wolftoothcomponents.com/products/roadlink) was installed to give the rear derailleur clearance for the
32t cog. The 105 long cage derailleur just barely has the capacity to handle the entire range.

In theory, this probably should not work perfectly, but it seems to work just fine even without the bash guard installed. The chain rubs on the larger ring when in the 24:11 position, but this isn’t a ratio one should be using anyway. However I think I could solve this problem with a longer bottom bracket spindle.

My son is planning to ride this on a mountainous road/gravel tour this summer. The original configuration had too many high gears and not nearly low enough gears. Now he has a range of 97-20.5 gear inches.

This photo was taken before installation of the bashguard. Obviously some swapping of shorter chainring bolts was needed to get the pictured configuration to work.
I can update the photo when the bashguard arrives.

^ perfect. I love everything about this. Would ride.
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