CyclingTips Tech Mailbag #4: How long is too long?
Washers and water and steerer tubes, oh my!
Washers and water and steerer tubes, oh my!
Welcome to the CyclingTips Mailbag column, where you send us your tech questions, and our team of nerds gives you answers. Got a question about wheel and tire standards? Want to know how to diagnose that weird shifting issue? Wondering where that darn ticking sound is coming from?! Send your questions our way at firstname.lastname@example.org to be featured in an upcoming CT Mailbag column.
In this week’s Mailbag, we ponder why water collects inside mountain bike frames, the need (or not) for pedal washers, and try to figure out how much is too much steerer tube.
Here’s a question that really bugs me: why do MTB frames fill up with water on a wet ride or hose-down? In other words, where is it getting in and is there anything that can be done to stop it? As well as adding weight until it slowly drips out making a mess, if you flip the bike to inspect or change pads, etc., the water gets in the dropper post and increases the prospect of it sticking. I’ve had this happen on a Trek Fuel and a Santa Cruz Blur, so it’s not frame-specific.
— Chris Gray
That’s a great question.
I’ve experienced the same thing on nearly every mountain bike I’ve had in recent memory (all of which were full-suspension). As for where the water is getting in, that’s an easy one: pretty much everywhere.
Modern mountain bikes — full-suspension ones, in particular — are chock-full of various holes and access points for cables, hoses, pivots, and so on. There are basically holes everywhere. However, unlike most road frames (or even many hardtails), what’s missing are drain holes at low points on the frame where the water can easily drain out.
Why don’t all bike brands include drain holes in intelligent places? Unfortunately, I have no idea. Seems kind of silly not to, but hey, what do I know.
Favero recommend washers for their pedals if the gap between the pods and cranks is not greater than 1 mm. However, if you need any support, they insist that they are necessary (even when clearance are within their spec). So are the washers necessary?
— Rhys Ashpole
Pedal washers are an interesting topic, particularly since major component brands seem to differ on their usefulness. SRAM still includes them with every crank and recommends them no matter what, for example, while neither Shimano nor Campagnolo seem too concerned if you use them or not.
The effectiveness of pedal washers in general is somewhat debatable, with proponents saying they can potentially prevent crankarm damage (and increase crankarm fatigue life), and the rest saying they’re superfluous.
Favero has a more specific reason for pedal washers given the large inboard electronics pod on the company’s power meter pedals. Some crankarms have recesses where the pedals mount, which can create clearance issues with that electronics pod. Favero is pretty clear in its written instructions on when — and when not to — use pedal washers, but clearly there’s been some confusion.
I reached out to Favero, and here’s what they had to say:
“Washers are necessary only if specifically required by the crankarm producer or if the crank arm has a recessed seat,” said Erika Martinazzo in Favero’s marketing department. “In general, you have to ensure at least 1 mm clearance between the sensor and the crank arm.
“Sometimes, when customers are not able to understand if the clearance is enough and we can’t understand it either through the photo (sometimes pics that customers send us are blurred or very dark), our support department simply suggests using one washer to be extra cautious.”
I own a 2020 Giant Defy Advanced Pro 2, bought just before the infamous 2020 lockdown. Despite being my best bike ever, I haven’t come to terms with the cockpit integration. After playing with stem height for a while I found my optimal position was leaving 1 cm of spacers under the stem.
Since reintegrating means cutting the fork steerer and shortening the hydraulic hoses, and taking into account my aging body may eventually ask for a more comfortable position, I decided to keep everything visible and with the original lengths, installing also a beautiful Ritchey 1 1/4″ stem. All things considered, the bike front looks more slender and I keep the option of changing handlebar height if I need it.
All this means that I have a 3+ cm-long segment of fork steerer above the stem. Also, the expander does not match the point where the stem is attached to the fork; it stays closer to the top of the steerer than the stem. I asked my local shop about if this setup was dangerous or whether I should go cut the bloody thing. They assured me that, if I did not over-tighten anything, it was completely safe. However, I still hesitate.
So my question is: what is the general advice for carbon steerer forks? Is it safe to keep a sizable part above the stem, or is it better to cut at least a portion, considering I would need in the future some extra height but surely not the whole of it?
— Suso del Rio
I hate to contradict the advice of your shop, but I think leaving things as they are is just asking for trouble. While I don’t think there’s anything inherently dangerous about leaving a fair bit of excess steerer tube (aside from the risk of impaling yourself in a crash!), there’s absolutely a risk of the stem clamp damaging the steerer tube if the plug isn’t sitting where it should.
Carbon fiber works great in tension, but it isn’t nearly as tough when it’s being squished. Steerer plugs prevent the steerer tube from being crushed as the clamp bolts are tightened, even when applying the correct amount of torque (and they arguably add bending strength to the steerer tube in general). However, the plug can’t do its job if it isn’t in the right place, and most aren’t designed to be used with a lot of steerer tube sticking out above the stem.
A longer compression plug can buy you some leeway, and my go-to has been the Gap Cap Expander Long from Pro. It comes in a 1 1/4″ diameter, and at 50 mm in height, it’s almost twice as tall as many common plugs so it’ll reach down into the steerer tube much further than the stock plug. Even so, the 44 mm stack height of your Ritchey stem still means you can’t leave too much excess steerer tube before the bottom of the compression plug sits too high to be effective. I personally try to never leave more than 10 mm of excess over the stem, but depending on exactly where the bottom of that plug ends up, you could maybe get away with 15 mm — but certainly not 30.