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Home > Forum > Triathlon Forum > Cutting Steerer Tube

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Cutting Steerer Tube
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iwaters
Jun 21, 17 1:16
Post #1 of 11 (1975 views)
My new P3 frame arrives next week! I am building up the bike myself. The fork comes un-cut so will need timing. Is this a hard job and should I do it myself? I have a good LBS but they are so busy they are taking bookings 3 weeks in advance and I want it ready for mid July. I need to go back to bike fitter to get the final tweaks made as well.

Just worried that if I get it wrong its a very expensive mistake. Is the steerer massive on it, I mean can I get away with some spacers above the stem for this season and get it cut over winter, or will that look rubbish or not work?
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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nickag
Jun 21, 17 1:24
Post #2 of 11 (1970 views)
It's a job you can do yourself. I cut my carbon P2 fork 8 years ago and I haven't had an issue.

Just check out some online resources - take your time, avoid splintering the carbon, use a fine tooth hacksaw.

Read the instructions for the fork, but you should always leave at least a little bit of steerer above the top of the stem to avoid the stem from crushing the end of the steerer. There's nothing wrong with leaving some extra spacers on top until you're totally happy with your position, you can cut more off later but you can't add it back if it's too short!
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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knighty76
Jun 21, 17 2:14
Post #3 of 11 (1956 views)
My P3C came with an aluminium insert to go in the carbon steerer, and it needed to be bonded with epoxy (or something) and left for a pretty long time to set. So I let the LBS do that one. When it came time to trim it down I did it myself, and cut through both the carbon and the aluminium. I bought the Park Tool SG-8 guide which makes it very easy to do in a bench vice.

I don't know if the new P3 has a similar insert, but if it does it is worth thinking about the placement if you are expecting to drop the stem down the line.
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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Morelock
Jun 21, 17 3:44
Post #4 of 11 (1929 views)
Fine tooth saw, NOT one of those pipe cutter styles that circle around to cut it (too much pressure on the carbon) then use a fine file to clean up the edges.
use a guide... don't just eyeball it.
measure twice, mark it, then put it back in the headtube and measure again. As above, you can't add more tube back once you cut it.

It's not a big deal to do, unless you fudge it up... then it's a really big deal ;)
My Blog - http://leegoocrap.blogspot.com
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Re: Cutting Steerer Tube [knighty76] [ In reply to ]
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nickwhite
Jun 21, 17 5:35
Post #5 of 11 (1889 views)
knighty76 wrote:
My P3C came with an aluminium insert to go in the carbon steerer, and it needed to be bonded with epoxy (or something) and left for a pretty long time to set. So I let the LBS do that one. When it came time to trim it down I did it myself, and cut through both the carbon and the aluminium. I bought the Park Tool SG-8 guide which makes it very easy to do in a bench vice.

I don't know if the new P3 has a similar insert, but if it does it is worth thinking about the placement if you are expecting to drop the stem down the line.

This. You definitely should use a guide to do it right, and get it perfectly straight. SG-8 is good, and for less money, SG-2 will do a fine job as well.
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Re: Cutting Steerer Tube [knighty76] [ In reply to ]
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iwaters
Jun 21, 17 6:19
Post #6 of 11 (1853 views)
Just read the instructions on the Cervelo websites. There is an insert that needs to be glued in.

It doesn't seem that difficult but the potential to make an expensive cock up worries me. Might just book it in to be sure.
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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iwaters
Jun 21, 17 6:44
Post #7 of 11 (1840 views)
Spoke to the LBS, £25 to cut and install, can do it in 2 weeks. The tools would cost about that and this way I don't have to worry. Just pressing in the BBRight BB to worrya bout now :-)
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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OddSlug
Jun 21, 17 7:08
Post #8 of 11 (1826 views)
Regarding positioning of the insert. Given the insert is 75mm and the max stack height is 35mm (not including cone) and a stem is about 40mm deep. Is the positioning of the insert for maximum flexibility as easy as it sounds? If the insert was glued so that it's bottom edge was level with the top of the cone then you could go right down to the cone or up to the max stack height.

It might even be that is why they chose to have a 75mm insert. It might even be that everyone already knows this and I'm stating the obvious.
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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Dumples
Jun 21, 17 7:15
Post #9 of 11 (1816 views)
I don't know about that steerer in particular, but I will add to what others have said about cutting carbon tubes in general. Use the finest tooth hack saw blade you can find, use a cutting guide, wrap the steerer tube with a layer of masking tape, and don't breath in carbon dust.
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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gphin305
Jun 21, 17 8:13
Post #10 of 11 (1787 views)
iwaters wrote:
My new P3 frame arrives next week! I am building up the bike myself. The fork comes un-cut so will need timing. Is this a hard job and should I do it myself? I have a good LBS but they are so busy they are taking bookings 3 weeks in advance and I want it ready for mid July. I need to go back to bike fitter to get the final tweaks made as well.

Just worried that if I get it wrong its a very expensive mistake. Is the steerer massive on it, I mean can I get away with some spacers above the stem for this season and get it cut over winter, or will that look rubbish or not work?


I'd recommend not doing any cutting until you ride the bike in a few events. I never cut the tube on my P4 preferring to be low and have a couple spacers above for Sprints and OLYs and then putting the spacers below for the few HIMs and IMs I've done. Remember doing a few events before settling on my desired position. Seemed to work for me and never looked out of place.
Last edited by: gphin305: Jun 21, 17 9:48
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Re: Cutting Steerer Tube [iwaters] [ In reply to ]
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STP
Jun 21, 17 8:49
Post #11 of 11 (1778 views)
Quote:
I mean can I get away with some spacers above the stem for this season and get it cut over winter, or will that look rubbish or not work?

It will look like rubbish but many of the young serious roadie racers in my circle have uncut steerers . They sell their heavily discounted bikes after each season and uncut steerers make them a bit more marketable to the old farts (like me).

So, for a season, you can pass off your uncut steerer as being "pro" ;-)
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