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Help, I'm going threadless! How long should steerer be?(9 posts)

Help, I'm going threadless! How long should steerer be?dugmn
Jun 5, 2001 8:12 PM
I want to replace my cro-moly fork with a threadless carbon fork. My head tube is about 15cm, how long of a steerer tube do I need on the fork? Supergo has some Time forks on sale, but they are cut to 244mm. Is that long enough? That would leave 9cm or so for the stem. The steerer tube is carbon. Any help would be greatly appreciated!
re: Help, I'm going threadless! How long should steerer be?Rusty Coggs
Jun 6, 2001 7:54 AM
If your HT is 15cm and you figure 4cm for HS stack height and 5cm for stem height= 24cm or 240mm. You really need to hnow the stack height of the HS you plan to use and the height of the stem you plan to use.Most HS are less than the 4cm I suggested and stem heights fall on either side of 5cm.The stem will also be about 3mm below the top cap in the final installation, so that gives a little more room.Also be certain of your HT length, as in this case, 'about' 15cm may not cut it,as things are close,but probably doable.
re: Help, I'm going threadless! How long should steerer be?dugmn
Jun 6, 2001 9:26 AM
Head tube is 152 or 153mm, don't have the bike with me. I'm using either a King 1" Threadless headset at 28mm stack height or a Record headset at 24.5mm. I'm going to use a 3TTT stem, either the Zepp or the Forgie. I'm trying to find out what the height of the stems are, but it sounds like it will fit if the stem is 60mm or less in height. Thanks for the help!
re: Help, I'm going threadless! How long should steerer be?Rusty Coggs
Jun 6, 2001 9:41 AM
The forgie is listed as 40mm.Don't have a number for the Zep. Another angle to consider, is where you want the final bar height. There is maybe room for about an inch of spacers,considering the parts you have chosen, so the stem rise you choose may be a critical factor.
re: Help, I'm going threadless! How long should steerer be?dugmn
Jun 6, 2001 12:33 PM
Right now I've got a Salsa quill stem with a 15-degree rise, and that works well for me. I haven't developed the lower back flexibility to run a negative degree stem yet, so I was going to run the 3TTT stem upside down to have a 10-degree rise. I'll probably use spacers to increase the height for the same reason. Is there a possibility of breaking the steerer tube by using spacers? The bike shop guy cautioned against a stack height more than about 25mm with a carbon steerer, but he didn't mention spacers.
re: Help, I'm going threadless! How long should steerer be?Rusty Coggs
Jun 6, 2001 1:56 PM
I think what the shop guy meant was spacers.The typically recommended limit I think is 20 to 25mm with a 1" carbon fork,but that may vary with manufacturer.
Thanks for the help!dugmn
Jun 6, 2001 2:13 PM
Wrong measurement???Kerry Irons
Jun 6, 2001 6:36 PM
Are you sure the 24.5 number is the stack height for the Campy headset? It's more likely that you've transposed some numbers and are either quoting the thread (25.4 mm) or crown race seat diameter.
Wrong measurement???dugmn
Jun 8, 2001 12:18 PM
I haven't actually measured the headset, I looked at the 2001 Campy catalog. It says 24.5mm height for a record threadless headset. I re-measured my headtube and it is 3mm shorter than I previously listed. So, I should be ok even if the catalog had the number wrong. Thanks.