Wednesday, March 31, 2010

Bike Diet - drive train

Tonight was the 1st "Taco Ride" of the season and everyone was out in force. I rode down to the trails from home and then did a little over an hour of riding. Round trip was 30 miles, so 37 for the day with the commute. The miles are starting to add up.

The main objective of tonight's ride was paying attention to my current gear ratios. I currently run a standard 22-32-42 in the front, and the rear is a cheap 11-34 cassette. The final three gears on the rear are 26, 30, 34. I rode multiple laps on hillside and could climb everything in 3rd or higher. However, by the end, I did jump down to the 30tooth and liked it. I can see using the 34 in rare instances, but it was only on the major climbing courses last year. I never used the granny up front and with the exception of commuting to trails, the 42 is rarely used as well.

So, part of the bike diet will be going to a 1x9 configuration. I hope to run something like this Truvativ Noir 1.1. It's light (750ish grams, I think) and looks good. However, anyone have input on other cranks? I'm guessing that my current 3rings and crankset are over 1000grams, so I can save a good chunk of weight here. New lighter SPD compatible pedals will also go on these.
The other benefit of 1x9 will be in dumping the front shifter (125grams), the front derailleur (another 125 or so) and cables. I also plan on converting to GripShift for the rear. I ran GripShift for several years "back in the day" and have no problems with them (another 100 or so in savings). I do need to keep the chain on the front rings and a friend just bought this from eThirteen. 56 grams, so plenty light and again, it looks good.
So the last part of the equation is figuring out which cassette to match with the 32 on the Noir crank. I had hoped to justify something closer to a 11-28, but the 11-32 (XT, XTR, SRAM 990?) will probably be the way to go. In the long run, I could jump up to a 34 in the front for faster courses and yet keep a good low gear for climbing. Current cassette is around 435, XT and SRAM 990 would save 160grams, XTR would be closer to 210.

If my math is correct this should save approximately 250 for the cranks, near 300 in the shifters/derailleur area and 160 on the cassette. Grand total of 700+ grams. Add that to the expected 800 grams in wheel set and tires and I should be close to 4lbs lighter on the bike. I haven't looked to see what could be saved in new bars, stem or seatpost.
So what have I missed? What are your thoughts on grams per $$ value on these parts or other suggested parts? Thoughts on the gearing choice?


Buckshot77 said...

PG990 cassette is a great bang for the buck. Much cheaper than XTR and I actually noticed the difference in shifting performance on mine when I put it on.

Good seeing you out last night.

BB said...

Sounds like you've got some good plans there for trimming down some bike weight, Tom.

I guess my only thought would be if your goal is to save weight on the bike - why not get one of the lightest cassettes out there while you are at it? 435g for your current cassette? You can really cut down from that weight.

My vote is for XTR in terms of price/performance and weight, but there are other options...

Nino's Ti cassettes are lighter and cheaper than SRAM XX and come in 9 and 10 speed versions:

And the newest option being the SRAM XX.

Have you thought about going 1 x 10 instead of 1 x 9? Of course, you'd need the new SRAM XX derailleur... Either way, the twist shifter is lighter than a trigger and very nice when racing.

I just figure if you could knock some grams off of the cassette if you are buying a new one, why not go whole hog? The XTR at 210 or one of those Ti cassettes from Nino at 167g would knock off some serious grams from your current cassette - that's for sure.

I've got both the XTR and Nino's Ti (the 11-34 versions) and they are nice cassettes. Shift great and have lasted more than a season.

The other 1 x 9 option for a 64/104 BCD crank is the Widgit from Australia.

No need for the eThirteen with it, but it only comes as large as a 32T. No 34T's (yet). I've read they might be coming in the future. Anyway, you could convert your current crankset (if it's 64/104, four arm BCD) for a bit less money. Still cut the shifter and front derailleur as well as the granny and big ring. And the Widgit is a built in chain guide - so the ring, bolts and guide are 110g total.

Iowagriz said...

Plans have changed slightly Bruce, Noir was too expensive, but I found "The Hive-G Fifteen" that is lighter 666+bb. However, it comes in 34t. I have yet to run the gear ratio numbers, but imagine that I'll go back to the 11-34 in an XTR.

I will check out the 1x10 xx option. Didn't realize they have a grip shift for it yet.

I have watched Nino's stuff. Maybe in the future. Need to talk to you more about it.