Monday, February 06, 2006

Weight savings tips for your cyclocross bike


So, whereas in an earlier post I mentioned that drilling your derailleur isnt going to turn your behemoth cyclocross bike into a lightweight wonder, it could help you drop that last 1/4 to 1/2 pound off your already light rig, and it might not cost you a ton of money either.

Covered in this post will be bolt tuning as well as switching out some common but heavier items in favor of something else. One caveat to everything about reducing weight is that durable and tough bikes are faster bikes than light bikes that break. Cause you gotta finish a race, and even if you have a backup bike, it probably wont break right at the pit. And obviously, durable AND light bikes are most desirable.

Bolt tuning refers to replacing heavy steel bolts with lighter aluminum or titanium bolts. The main reason why a stock bike or stock components come with steel bolts is that steel is much cheaper than titanium and slightly cheaper than aluminum. For the most part, you dont need steel bolts anywhere on your bike. Titanium is a lighter (however, costlier) option. And there are only two places where you need the strength of titanium rather than aluminum, thats the stem bolts and the seatpost (also I've never had good luck with aluminum brake cable stop or derailleur cable bolts). Aluminum is a great material for many bolts on your bike, because its lighter than ti or steel, and cheaper than titanium (also it comes in rad colors). Places where aluminum bolts are good are:

cantilever brake mounts
derailleur pulley bolts
chainring bolts
bottom bracket bolts
water bottle mount (see more info below on plastic plugs)

I've taken some pictures of these items on gram scale to show how much weight can be saved from switching from steel to aluminum or ti (Blogger isnt letting me load anymore pictures than those below).

First lets look at water bottle bolts.



A pair of steel waterbottle bolts weigh in at 6.5 grams.



The aluminum equivalent weighs over 4 grams lighter at 2.3 grams.



And heres the lightest and even the cheapest option. Plastic plugs weigh in at .4 grams and cost me 50 cents at my local hardware store. They only come in white, but if you wanted, you could spray them black or whatever color you wanted really.
Item





Steel


Aluminum

Water bottle






6.5



2.3

Stem bolts






19.7



11 (not aluminum though--ti)

chainring





26.2


10.3
bottom bracket






36.9


18.2


Some other light choices are:

Carbon steering tube spacers save 2.8 grams per 10 mm over aluminum.

My Chris King topcap with steel bolt weighs 17.3 grams. You could either replace the steel bolt with an aluminum one, but a cheaper and lighter option would be to put a beer bottle cap (2.2 grams) in its place or a carbon topcap that presses into place (like those made by Schmolke---but you can make these at home fairly easily)

Lastly, instead of using a front cable hanger (30.3 grams) that you'll find on 99.5% of all cyclocross bikes out there. Use a rear cable hanger (4.2 grams after i "tuned" it a bit) thats bolted onto the stem's faceplate.

So let me get out the calculator and do some math on how much weight we saved:

-12.2 grams for the waterbottle mount (ill assume you have two of them)
-8.7 grams for the ti stem bolts
-15.9 grams for chainring bolts
-18.7 grams for the bottom bracket bolts
-15.1 grams for the Topcap switch
-26.1 grams for the front cable hanger
-11.2 grams for the carbon spacers (assuming you have 40mm of spacers)

=107.9 grams.

And I didnt even include the aluminum cantilever brake mount bolts (which might be another 20 grams) That brings you to 1/4 pound lighter. So, if youre out of options or dont want to throw down several hundred dollars for a lighter component, some small upgrades like those above can actually make a difference. And some of the options above are almost free.

6 comments:

Anonymous said...

Nice tutorial on light bolts. This weight savings should be considered the icing on the cake. The total savings is only 1/4 lbs. My suggestion is to look at light tires / tubes and pedals / shoes to save a larger overall weight.

dyg2001 said...

Where do you get these Al and Ti bolts? Can you post some links to reliable vendors? Thanks.

Anonymous said...

try www.racebolts.com

Anonymous said...

The biggest weight is sitting on the bike. I reduced my weight by 5 kg without any expences.

Phil said...

A blogger asked wear to get lightweight fasteners. I have used 2, use Google and find, Specialty Racing Products(Massachusetts) or Racebolts.com.

Good Luck.

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