|Double Chainring Limitations and New Bikes||mgolebiewski|
Apr 2, 2003 9:28 AM
|I have a pre-existing knee injury (chrondomalatia(sp) of the patella) this requires me to climb at a higher cadence and lower gear to reduce the stress on my knee. I simply can't grind my way up the hills without pain and possibly long term damage to my knee, but I can spin all day.
My problem is that that I am looking for a new bike and am very limited by higher end bikes, epically used on e-bay, that have a double chaining. My belief is that I need a triple to get the gear ratios I need for my riding style.
Is there any way I can get the same gears in a double ( I am presently running a 52/42/30 with a 23-12 cassette)? If I can get those gears will I be at the limits of the drive train if I decide to do some mountain riding?
How hard is it to move a double to a triple? As I understand I will need to replace the bottom bracket and cranks. Will I need a new shift lever and is there any way to tell if I will need one in advance?
Any other bits of advice anyone can pass along as I am quite frustrated by my lack of options(both new and used) with a triple?
Apr 2, 2003 9:41 AM
Apr 2, 2003 11:34 AM
|I am running Shimano now, but have no problems w/ moving to Campy if it will help my situation.|
|You can get close to the same gearing...||Nater|
Apr 2, 2003 9:59 AM
|as your triple setup if you go to a Campy 10 speed setup with a 39/53 crankset and a 13-29 cassette.
As far as a conversion to triple from double...you'll definitely need the crankset and BB, probably new derailleurs (front and rear), and maybe a new left shifter too (depending on the vintage). Newer Campy and Shimano front shifters are double and triple compatible.
|re: Double Chainring Limitations and New Bikes||Spunout|
Apr 2, 2003 11:29 AM
|30 X 23 is 1.3 ratio, and a C10 setup with a 13/29 on the back will give you 1.34, which is close enough to being equal.
Be careful on EBay. Optionally, buying from a shop gives you the option of having a bike spec'd with a triple setup, which will save some money.
Some left shifters are triple compatible, like new Chorus 10 speed, and Ultegra (I think). You may not need new shifters.
|re: Double Chainring Limitations and New Bikes||Rusty Coggs|
Apr 2, 2003 1:31 PM
|All shimano 9 speed shifters with the exception of pre 2002 DA will shift a triple.The is now a triple DA option.All campy ergo front levers shift a triple. His 30x23 triple gives 35 gear inches and has plenty of additional range to 30 gear inches with a 27 cog and even more with a smaller granny.A Campy 10 speed double with 39x29 gives 36 gear inches and is at the end of its range. A Shimano double with 39x27 is good for 39 gear inches but the derailer would likely shift a 30 cog.Shimano also gives the option of MTB cassettes/derailers for cogs up to 34.|
|"buying from a shop...will save some money" Hah!||Matno|
Apr 4, 2003 6:47 AM
|If you can get a price from a bike shop that is even remotely close to what you can get a nice bike for on eBay, you're not searching eBay very well. There is no way that bike shops can hope to compete in the used bike market based on price alone. As long as you stick to sellers who have good feedback and are PayPal verified, your chances of anything going wrong with an eBay transaction are pretty darn slim.
As for the gearing question, I'd say going with a MTB rear cassette and derailleur is probably the easiest and cheapest way to get lower gearing. A 12-34 cassette will give you a low gear ratio of 1.14 with a 39 tooth front ring. That's pretty dang low for a road bike and noticeably lower than the 1.3 you have now. (Almost 10% lower). You'll have a little bit bigger jump between gears on the low end, but if you're like me, when you need a low gear, you need it all the way low and can jump back up when you get to the top of the hill!
Apr 2, 2003 2:21 PM
|....if you want to keep your double, and this only works with Shimano, is to install an MTB rear dérailleur (like an XT or XTR) and an MTB cassette in 12-32 or 12-34. This will get you gearing very close, or even better than the triple, and the cost should be around $100.00 or so. You will also need a longer chain. It's a simple matter to install and have running quickly and you always can revert to your original configuration easily.|
|And also ...||KeeponTrekkin|
Apr 2, 2003 2:57 PM
|you can buy custom built cassettes or individual cogs from Sheldon Brown / Harris Cyclery and modify the road cassette that comes with the bike you buy. You might be happier with a pattern that has narrower spacing between the high gears and very wide spacing between the low gears - "Alpine gearing" vs. an MTB cassette which has more even, but wide spacing and thus, wider gaps in the most useful road ranges.|
|re: Double Chainring Limitations and New Bikes||tobinb|
Apr 3, 2003 9:51 AM
|here is one option: If you are ever interested in swapping a double for a triple we can help out each other. i have a 105 triple and ive never used the inner ring. mail me if you are interested!
I am surprised that in shopping for a higher end bike a shop wont swap it out for you.
|re: Double Chainring Limitations and New Bikes||mgolebiewski|
Apr 3, 2003 1:06 PM
|If I get something with a double I may take you up on the offer. However, for now I am still searching for the right bike.
Most shops seem willing to do a conversion with some cost passed onto me. What cost seems to depend on how far the bike is marked down already. So it is probably more fair to say I am being eliminated from alot of good deals right now.