|Gearing suggestions for climbing bike?||Dog|
May 2, 2001 5:44 PM
|I've built up my old EV2 for a pure climbing bike. The goal is to make it as light as possible, and have gears that will enable me to climb straight up a wall spinning in the saddle, even after hundreds, or even thousands, of miles.
I want to use downtube shifters. I installed Dura Ace downtube shifters, 38/48 chainrings on a DA crankset, a 9 speed XTR 12-34 cassette and XTR short cage derailleur, and rode 90 miles up the Climb to Kaiser route here (up long 20% grades), and it worked pretty well, with some problems. The 34 is too low; I could easily spin it up a 20% or more grade; I could use an XT with taller gears - 30 or 32, but they are really heavy. Keep in mind that Shimano fixes together the largest 5 or 6 cogs on these things. The rear shifter would not hold against the spring in the XTR derailleur - kept popping out of position into a smaller cog (the shifter can be set to either friction or indexed mode). Plus, the spacing on the XTR is too large.
So, I'm considering other options, and would like technical input. I want to make this work with my Shimano cassettes (and don't want to use Campy adapter cassettes), and probably need the equivalent of a 38/30 ratio. The 12-27 DA cassette I have probably is not quite enough for the potential conditions I might meet.
1. Would the Campy "racing' Triple work with a Shimano cassette, chain, and rear derailleur? I realize I'll need the Campy bb and front derailleur; however, will the triple front derailleur work with the downtube shifter?
2. Instead, would it be better to use an Ultegra triple? (I like the ratios of the Campy better -- 30-40-50, instead of the Ultegra 30-42-52).
3. Any other suggestions, keeping in mind the primary goals of weight and low gears?
|re: Gearing suggestions for climbing bike?||DaveG|
May 2, 2001 7:39 PM
|Doug, you are never satified are you?! (just kidding) Anyway, I have not tried it but I'd be doubtful that a Campy triple crank and der. would work well with a Shimano shifter in indexed mode. I don't see it working with a DA shifter because it doesn't support a triple option. Friction mode should be fine - and quite retro. The rear Shimano cassette, der. and chain should not be a problem - many folks do that. Personally, I'd stick with the Ultegra route - perhaps there is an aftermarket chainring manufacturer that allows a 30/40/50. Yet another option, would be the Lance plan. Use a STI shifter for the rear and then use a Campy downtube shiter for the front. Might be a few grams heavier than dual downtubes, but would be more fun on the flats.|
|re: Gearing suggestions for climbing bike?||Larry Meade|
May 3, 2001 6:25 AM
The down tube shifter for the front derailleur should work for just about any double or triple made. It is simply a friction style lever and as such should pull all the cable you need for whatever setup you decide on. I would be tempted to ride the setup you have now until the new DuraAce triple comes out. Then all you would need to switch would be front derailleur, crank and bottom bracket. The reason I would hold out for DA is that I have heard it will come with 53/39/30 chain rings. Thiw will give you much freedom on what cogs to use on the back. To me, this is a much more friendly gearing than the 52/42/30 that currently comes with Ultegra. Just my opinions. I am currently planning on building up a long distance/all day bike and will put the DA triple on when it comes available.
|re: Gearing suggestions for climbing bike?||muncher|
May 3, 2001 8:07 AM
I tried a Shim block with my Campy Racing Triple - no dice, shifting useless, tolerances too small, but only with ergos - no reason why it wouldn't work non-index with down tube, and you might find that the slack is more on indexed shifters if you are lucky (assuming that D-A is switchable - only ever had 105 downtube shifters). You might have a fix with a slightly narrower chain if you have clearance/shifting problems - I think there is a Sachs chain which is a little narrower than the standard Shim on.
Thought though - the "solid" shim blocks used to be held with (4?) pins through them - you could grind the heads off to get them apart, and thus change the ratios to what you wanted. Might be the cheap and easy solution? Not looked at one lately, so maybe you have tried this and they have changed the design?
Sounds like an interesting project anyway.
|12-23 and triple crank...||dave|
May 3, 2001 3:40 PM
|A standard 12-23 cassette with either of the triple cranks would produce the desired equivalent of a 38/30 low gear.
A downtube shifter will work any front derailleur, at least in friction mode.
Personally, I think Campy's 13-29 10 speed cassette with the long cage derailleur and a double crank would be your best bet. There's only 3% difference in the low ratio.
I also think that your light weight obsession is just that, an obsesssion. Saving two or three ounces by using downtube shifters won't produce any measurable benefit. In fact, one fumbled shift could easily erase any gains from the weight savings. Even the extra effort of reaching for the downtube shifter can result in a loss of concentration and a brief reduction in cadence, which detracts from maintaining a steady pace. I'd stick with Ergo, it allows you to concentrate on pedaling, which could result in a faster average speed.