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Old 05-20-09, 12:20 AM   #1
Sirrus Rider
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Tripling a 1988 Specialized Sirrus

I am thinking about modernizing my 47 cm '88 Specialized Sirrus by putting a triple crank set (either Sugino or Shimano 105) on. I know this step is bordering on blasphemy, but my 40-year-old legs need more ratio range for handling hills than my 39/52 double permits. Additionally, I believe I'm currently running 170 mm cranks, but they could also be 175mm as I lack an accurate means of measuring. Is the 5 millimeter difference significant in feel or ability to spin? Also, assuming that I only change the the crankset could I get away with continuing to use my downtube front shifter? Or am I just working up a good excuse to buy a Jamis Aurora and put my Specialized Sirrus out to pasture?
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Old 05-20-09, 02:48 AM   #2
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First it isn't blasphemous at all. There's nothing wrong with a triple. Second, you’ll need a new crank, BB, front derailleur and rear derailleur. The shifters should work. IMO, buy an old MTB and use the group on it. Try to find a steel bike with a 28.6 clamp on ft der. You should be able to get the parts off it. Then you can sell your parts and the rest of the MTB to defray the cost. Good luck.
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Old 05-20-09, 05:54 AM   #3
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Originally Posted by Sirrus Rider View Post
I am thinking about modernizing my 47 cm '88 Specialized Sirrus by putting a triple crank set (either Sugino or Shimano 105) on. I know this step is bordering on blasphemy, but my 40-year-old legs need more ratio range for handling hills than my 39/52 double permits. Additionally, I believe I'm currently running 170 mm cranks, but they could also be 175mm as I lack an accurate means of measuring. Is the 5 millimeter difference significant in feel or ability to spin? Also, assuming that I only change the the crankset could I get away with continuing to use my downtube front shifter? Or am I just working up a good excuse to buy a Jamis Aurora and put my Specialized Sirrus out to pasture?

Triples are great..... no worries about it. A Sugino triple is a great way to go, as it would give you more usable gears for you, as opposed to a road triple like the 105, which has larger chainrings. Your shifters are fine. The Sugino triple can be had with various rings. 26/36/46 common, but www.rivbike.com sells them with a 24/36/46, and www.velo-orange.com sells them with a 26/36/48. You don't need a 113mm BB, no matter what the specs say. A 110 or 107 will fit fine on your frame.


Your current cranks should be marked, look at the back side of them. 175 may be too long for you, as you say the frame is only 47cm. But try these crank length formulas for the heck of it and see.
http://www.nettally.com/palmk/crankset.html
http://www.peterwhitecycles.com/fitting.htm

Triple FD and RD's can be had real cheap on ebay if you know what you need and are disciplined enough to not overpay. But, I get the feeling you don't really know what you need, so I'll try the best I can to convey to you in this short space how to best assist you.

What you don't want for a FD is a new, modern one. They are designed as systems for certain rings and they just are not fun. Get something from the 80's or early 90's. Here's two perfectly good FD's that'd work, assuming it's a bottom pull, 28.6 tube:
http://tinyurl.com/oay3pp
http://tinyurl.com/pa83vb

For a RD, any modern or older triple will work for you. You don't need it to be deluxe.
I use one like this, it's a great friction RD, and inexpensive. You can probable get it for less than $10 or $15 with shipping. Don't let the scratches deter you, the pulleys appear to be good.
http://tinyurl.com/ra47pf

Or get a new Deore, what a deal ! http://www.cambriabike.com/shopexd.a...EAR+DERAILLEUR

I hope that help you.
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Old 05-20-09, 12:36 PM   #4
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Originally Posted by cs1 View Post
First it isn't blasphemous at all. There's nothing wrong with a triple. Second, you’ll need a new crank, BB, front derailleur and rear derailleur. The shifters should work. IMO, buy an old MTB and use the group on it. Try to find a steel bike with a 28.6 clamp on ft der. You should be able to get the parts off it. Then you can sell your parts and the rest of the MTB to defray the cost. Good luck.

Okay maybe I wasn't clear, but the 48/52 for most of my riding is still fine. I just want a bailout gear for big hills; consequently, a MTB group won't work as it won't have a high enough high end.
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Old 05-20-09, 01:19 PM   #5
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Depending on how much you want to spend and just how high and low of gearing you want, you have a few options besides a triple.

The cheapest option would be a different cassette/freewheel. You have many more options with the cassette but if you are stuck with a freewheel, you can still easily find freewheels with a 34 tooth bailout gear. The only other change you'd need to make would possibly (though very likely) be a different derailler. You would have greater spacing in between gears though.

The second cheap option is a compact double crankset. There are a few compacts out there that will work with an 8 speed chain though most will require switching to a 9/10 speed chain. The compact will keep your spacing between shifts at the expense of lowering your top end gearing and having a larger jump between chainrings. You also won't have as low of gearing as a triple would offer with the same cassette.

A compact coupled with a wide range cassette will get you the gearing range of a triple at the expense of larger gaps between gears.

As usual though, my vote is for the triple. Follow Garthr's advice, and you'll be set. You can modernize one step further by adding some low end/older Shimano STI's like Sora or RSX either of which can be had on Ebay for less than $50/pair.
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Old 05-20-09, 01:30 PM   #6
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Originally Posted by Sirrus Rider View Post
Okay maybe I wasn't clear, but the 48/52 for most of my riding is still fine. I just want a bailout gear for big hills; consequently, a MTB group won't work as it won't have a high enough high end.
Do you want to check the size of the inner ring again. In your opening post you say 39/52.
If the 47 cm frame fits you well then the 170 mm cranks are probably the best size. Smaller cranks spin better.
If your front shifter is friction, not indexed, then it should work well with a triple.
A compact double could be a good choice. These are available with 34/50, 36/50, and 34/48 chainring sizes. And other combinations are possible. Usually a 50 big ring is big enough, but of course that also depends on what you have in the back.

Al
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Old 05-20-09, 09:13 PM   #7
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I converted my Sirrus, which I think is a '91 (Suntour Blaze components), to a triple by buying an old partly-broken mountain bike and harvesting the crankset and front derailer. I also had to get a new bottom bracket, which was fine by me since the old one was well pitted. It made the q-factor a little wider, but still acceptable.

I didn't even need to change my rear derailer, I think because the freewheel is 13-24 so I had some range to spare.

My new crankset is 28-38-48, so you wouldn't have your 52t top gear, but that could possibly be addressed by a smaller rear cog or by replacing the large chainring. For myself, I haven't been bothered by spinning out at 35mph on my commute...
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