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Cut down my carbon fiber bars & took some excess seatpost off (how-to guide).

Friday, September 14, 2012 by  
Filed under Daily Blog

September
14
2012
Materials I used to cut the carbon bars and seatpost: Hacksaw, 32T carbon-specific hacksaw blade, saw guide, masking tape, thin sharpie, zip tie, water and a digital caliper. Not pictured is a painters mask and 400-grit sandpaper.

Materials I used to cut the carbon bars and seatpost: Hacksaw, 32T carbon-specific hacksaw blade, saw guide, masking tape, thin sharpie, zip tie, water and a digital caliper. Not pictured is a painters mask and 400-grit sandpaper.

In Tuesday’s blog I mentioned that my Truvative T40 Noir 700mm carbon handlebars were a little too wide for my liking, and so yesterday I decided to do a little surgery on them.

Cutting down carbon bike parts is not a difficult task, but it does require attention to detail and care to do the job right. Also, while I was at it, I decided to trim off a couple inches of excess seatpost for a bit of extra weight savings.

Here’s a list of the materials I used to do the two jobs:

Truvativ T40 Noir Carbon bars in the guide and ready for cutting.

Truvativ T40 Noir Carbon bars in the guide and ready for cutting.

“Measure twice and cut once” is especially important before you go hacking up your expensive carbon fiber bike parts. I used my inexpensive, but very useful, Neiko 6-Inch Digital Caliper with Extra-Large LCD Screen & Instant SAE-Metric Conversion to ensure that I was taking off precisely 15mm from each end of the handlebars. Also, before you cut down your bars make sure that your particular model of bars can safely be cut. Check with the manufacturer if in doubt.

A couple wraps of masking tape will help prevent the carbon from fraying and help ensure a nice clean cut. Once you’ve determined the general location of where you’ll be making the cuts, put on a couple wraps of masking tape and then use a zip tie (as a guide), a sharpie and the digital caliper to add the precise cut marks.

It’s important to use a a fine 32T hacksaw blade; the more common 24T blades will not make nearly as smooth a cut. For the carbon handlebars I used the Park Tool Carbon Cutting Saw Blade (CSB-1). This blade is a tungsten steel hacksaw blade specially designed to smoothly cut carbon composites.

Another tool that makes this job much easier and more precise is a saw guide. I have the Park Tool Threadless Saw Guide for Carbon Composite Forks (SG-8), which is worth its weight in gold. Simply clamp the tool into your vise and you’re ready to go. The SG-8 has a rubber internal clamp that helps hold the part you’re cutting firmly in place. Very useful tool.

Trimming excess seatpost will save a few grams of useless weight. It's important to leave enough tube to adhere to the factory recommended minimum insert length.

Trimming excess seatpost will save a few grams of useless weight. It’s important to leave enough tube to adhere to the factory recommended minimum insert length.

Spraying the hacksaw blade with a little water before making the cut helps the job go a little easier, and also cuts down on carbon fiber dust. You definitely don’t want to be breathing that crap, so you should try to do this in a well-ventilated area and also wear a particle respirator.

Once the cuts are complete, you may want to use a little 400-grit sandpaper to smooth the edges a bit. If you follow all the above advice, you’ll probably find that the cuts are already really smooth and don’t require much, if any, sanding.

After I completed cutting my handlebars down, I also cut some excess seatpost tube off to save a few extra grams of weight. It’s very important to note the minimum insert length of your seatpost, and leave enough tube to adhere to that specification! I was able to trim a couple of inches of my seatpost, and that saved about 27 grams of weight. 27 grams is not much weight, of course, but cutting excess seatpost is free and super easy. Might as well trim off useless dead weight, right?

Truvativ T40 Noir Handlebars reinstalled after being cut down to 670mm.

Truvativ T40 Noir Handlebars reinstalled after being cut down to 670mm.

For the seatpost I used a 32T metal hacksaw blade, but apart from that the method I used was identical to how I cut the handlebars.

My T40 Noir handlebars are now 670mm wide, and I think that’s going to make a big difference on the tight and twisty singletrack I like to ride. The 700mm bars felt great to me, but I’d grown so used to my old bars that the wider stance of the Noirs was really creating problems (often painful problems) for me out on the trails.

I took the bike for a quick spin after completing the work, and the 30mm difference was certainly noticeable, but not uncomfortably so. I’ll take the bike on the trails over the weekend and see how she feels there.

Bike weight down to a new low of 26 lbs 09 ounces.

Bike weight down to a new low of 26 lbs 09 ounces.

Finally, after yesterday’s project my bike is down to a new low of 26 lbs 09 ounces. Before I did all the upgrades to my Fuel last March, she weighed in at 30 pounds 11 ounces. Most of the weight reductions I’ve made have been rotational weight, and that difference has had a huge performance impact.

Obviously I’m being a real weight weenie here, but being so close to putting the bike into the 25s is driving me nuts. There’s really not much more I can do to reduce the weight of my bike apart from a carbon seatpost, ultra light tires and lighter grips.

The carbon seatpost would only save me a couple dozen grams (at best), and is simply not worth the high expense. My current Wild Grip’r tires are already quite light at 560g each, and I love the way they perform. So I’m not going to change the tires, at least not anytime soon. I also really dig my current grips (ODI Rogue lock-ons), but they are fairly heavy (as grips go) at 132g. My friend Craig has been after me to try the ultra-light and very inexpensive ESI Racers Edge Grips (which weigh just 50g), and so that’s what I’m going to do. With the ESI grips I’ll be saving 80g of weight for next to nothing in cost.

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