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I have a Ragley Trig frame & fork. Ragley have been quick to answer queries, although not always with the same information
To cut a long story short, when finding out about expander bungs (new to me) I came across the idea that carbon steerers generally have a maximum amount of spacers allowed under the stem. I gather that this is a safety issue.
Ragley initially told me that there were no restrictions but suggested no more than 40mm. I"ve since been told that actually it's 30mm & that they haven't tested beyond this.
So, what are people running and any issues? I gather from the Trig thread on here that it has quite a low front end and I don't want too acute a ride position, just something comfortable for pootling. Equally it needs to be safe.
What size are you and what size trig did you buy? I went for the large rather than the medium for the taller head tube and a very modest difference in reach. I'm very glad I did for both the stack and the reach.
30mm is pretty much the standard max advised for spacers on any bike/fork.
You could always ride a flipped stem. Aesthetic heresy on a road bike, but the trig doesn't really have a road bike feel/look.
I'm 5"11 with a 34" inseam and went for a large.
Pretty much identical to me then. You'll be fine I'm sure. Not sure what I'm currently using, but defiantly not the full 30mm.
Cheers, I might need to shave a bit more off the steerer then.
I was under the impression that the spacer stack max. was just for carbon steerers, I've seen some tall stacks of spacers.
Ragley initially told me that there were no restrictions but suggested no more than 40mm. I”ve since been told that actually it’s 30mm & that they haven’t tested beyond this.
They're just covering their arses. All they said is that they tested it with 30 mm and it's fine. Honestly, the stress on that part of the steerer is a fraction of the stress around the lower headset bearing, with the entire length of the fork and front wheel as leverage.
On top of that, if it's only safe with 30 mm spacers, they would have also warned about fitting riser bars. The leverage comes from how high your hands are above the headset bearing, not just from how many spacers there are. I would be absolutely fine with 40 mm spacers. If that 10 mm difference is enough to make it unsafe, it's unsafe with 30 mm too.
what thols said.
30mm is pretty much the standard max advised for spacers on any bike/fork.
That’s the normal limit for a carbon fork. I need quite high bars so it’s been restrictive for me in terms of frame and fork choice. Currently I have a flipped stem on a steel fork. The whole thing is a bit of a mess with a straight steerer fork in a tapered aluminium frame. But it works so I don’t really care.
A shorter stem and short reach bars might be an option to reduce reach rather than increase stack. Although I’m never clear about the bar height bar reach relationship
They’re just covering their arses.
Probably, but having now said 30mm, if I set it up with 40mm and something were to go wrong, I guess they'd play their 'not set up to spec.' card.
Since the fork is a full carbon one, with max. spacer and torque requirements I was surprised that there was no paperwork (or online tech. documents - unless I've missed them) stating these with the frame (I only found out by chance, and with the help of someone on here, that the fork has an integrated crown race with the bearing sitting directly on the fork's taper and needing a 36° angle of engagement, if I hadn't I could see myself having done some damaged trying to fit a crown race).
I guess that I can try 30mm without trimming the steerer further and go from there. I'm new to drop bar bikes so there'll probably be a bit of tinkering.
I'm on a medium and would've guessed I had about 30mm, but just checked and it's 15mm.
Doesn't feel low, so I reckon you'll be fine.
Honestly, the stress on that part of the steerer is a fraction of the stress around the lower headset bearing, with the entire length of the fork and front wheel as leverage.
This is true though the steerer construction at that lower HS end (partic on a taper steerer fork) is also very different. The majority of broken or damaged carbon forks I've seen are the blades or at the steerer around the upper HS bearing, spacer or stem area.
A common guide for a carbon steerer is not to go much beyond the tube OD with the spacer stack height and that's where the common 25-30mm stack comes from, it's just he common amount used on bikes since Aheadsets became common. It would take some pipe or composites expertise that I don't have to validate any engineering behind that guide - a lower stack will flex less but it's still metal edges indenting the steerer that seem to cause the problems.
EN tests for forks include a steerer tube loading test that states that the stem and spacers specified should be used, or the maximum stack and stem length specified by the manufacturer. This test was only introduced fairly recently though.
Anyway, I'd agree that going from 30mm to 40mm isn't likely to be a risk, considering all the other variables. Personally I would set it up with 30mm underneath and space for 15mm on top to begin with, so if you need the 40mm underneath you'll still have 5mm out the top for full steerer-stem contact (important). Close-fitting, well machined spacers can help support the stem to headset as a system fwiw.