So many times I have a question about something technical or mechanical and can’t find the right answer online, so maybe we can help each other here. Have you just installed some new shiny parts on your bike? Trying to fix something and confused or can’t find a torque spec? Etc etc
Throw up a question, let someone else answer, and if you remember edit your post with “Answered” to avoid a lot of redundancy. If you answer a question try to use the quote function so future generations can see what you were answering. Or just show off some new bling on your bike!
I’ve got a question. Was checking over bolt tightness on the road bike. Remembered a weird ticking from my crank R8000 so decided to one by one remove the inner bolts, clean, anti sieze, and retorque to spec. Shimano manual calls for 12-16nM so I went for 14 and sheared the head right off.
It’s a T30 bolt but the bit doesn’t go very deep inside and effectively grabs just the head and not the body, so all the torque is applied at the head. I did order a spare set, didn’t bother with the other 3 for now but read this is kind of common
Any tips or advice for “better bolts”? Maybe an aftermarket T25 where the socket can go deeper inside? Maybe steel or titanium instead of aluminum? Maybe disregard Shimano torque spec on these? Just trying to prevent tearing up a new set of bolts immediately if I can help it
I doubt you’ll be able to use a different sized bolt - the ‘30’ part relates to the diameter of the threaded part. The length of the threaded part comes after, e.g. T30x10 would mean the threaded part is 10mm long. To be honest I wouldn’t use a different sized bolt - it categorically will be the correct size for the job IMO. It needs to be snug on both sides.
I tend to tighten aluminium chainring bolts to about 10nm with a smear of blue loctite. 12nm should be fine though really, but you can get away with lower torque if you use loctite - it would probably solve your clicking as well!
Can’t help with the bolt but one little pointer I wish I knew before I found out the hard way…
When buying a dropper post lever, it’s way easier to buy one where the cable length is determined at the lever and not in the seat post. Once you have some experience either way is not bad but if you are building a frame from new without the cable housing as a guide, the lever option is just loads easier to install.
The reason, you don’t have to really be precise with cable housing length. Snap the barrel end into the dropper and then pull it tight at the lever. Tighten the set screw and boom. From there I actuate the cable several hundred times and then tighten again, trim and crimp. Super duper easy that way.
The list of fasteners I’ve broken is too long to count. I’ve done the same thing to a couple of sram crank arm bolts and rounded a couple of chainring bolts to be specific. Main issue, applying anti-seize (grease or oil) lowers the thread friction when tightening fasteners. This means more clamping load between parts being fastened and increased tension in the fastener, therefore higher likelihood of damaging the fastener. This is especially true for fasteners that are not forged.
So, what to do? Rule of thumb is to lower the application torque about 30%, or use the low end of the torque spec as the new high end.
Also apparently derailleur hangers can bend on their own. I noticed my derailleur looked bent when I looked down riding so ordered a Wheels MFG unit which by the way looks way nicer as far as being CNC machined vs cast like stock. I’ve never crashed the bike or leaned it on anything but my LBS did comment that my QR were too damn tight so maybe that bent the hanger over time?
Feels like this thread may need multiple sub-threads, as there’s so many different potential topics to cover.
My question is a different topic vs those above: how difficult is servicing a rear shock vs. front fork on a MTB?
I’ve done 2 different forks. They were messy (fckn fork oil), and took me longer than the various guidelines said, but I was pretty confident in the work I did. Is a rear shock about as hard?
A simple air can service is pretty easy, changing out the seals and lubricatng. Going deeper into the damper is a bit more involved and depending on the shock may require specialist tools or nitrogen charging.
Personally I go as far as the air can on the rear shock, but send it away for damper servicing. I have the skill but the investment in additional tools isn’t worth it for the amount I would use them (and normally I like nothing more than buying bike tools).
Shocks require high pressure nitrogen charge, some require the use of a specialty safety needle. None of it is rocket science but if you’re not going beyond your own equipment, you’d have to be pretty invested into the tooling. My take, stick with forks and air can services. When you did your fork repairs, did you service the dampers?
So I’ve upgraded my FSA gossamer crank to a 6800 hollowtech crank. My bottom bracket is a bb30 so I’ve fitted reducers rather than changing the BB.
My question is do I still need to fit the wavey spring washer that came with my gossamer crank? I’ve assumed it’s redundant due to the preload adjustment on the 6800 crank?
Unlikely… the winter bike is lucky it’s getting 4 year old hand me downs as it is! Not going to be spending money on her if I can help it. Cheers for the reassurance
I’m not sure about DVO specifically but Reservoir shocks typically see significantly lower IFP PSI spec and some reservoir (piggy back) shocks can even be charged with a standard air shock pump. Reality is you don’t actually need nitrogen to charge a shock, it’s just “best practice”
On the subject of fork servicing, I opened mine up yesterday and noticed something I’m always dreading - I have some wear on my kashima coated stanctions This is hidden when assembled - damper side only about the bushing level.
Pretty annoyed because I thought I was on top of the servicing, been less than 6 months since last oil, seal, foam ring replacement. Not even riding this bike every weekend.
Question is, how worried should I be? Don’t think it will change my action which is just to service and ride as usual, anything I should watch out for?
Can you feel the abrasions with your finger? If not, I think likely not much concern.
I put a scratch in one of my stanchions when I fell over on a tricky rocky technical ascent. It was deep enough where I could feel it. I rode another couple of rides and noticed the scratch had gouged the seal, and as a result, oil was making its way past the seal. I used nail varnish to fill in the scratch and sanded it down. Then replaced the seals. It’s been working fine so far. But at some point I may replace the nail varnish with epoxy.
I can just about feel it, it’s very light. Oil leaks would be my initial concern but since this is inside the fork and never passes the seal I don’t think it’s a worry. I’ll ride it and check the oil in a couple of months to see if I’ve lost any or if it’s getting contaminated.
This is hidden when assembled - damper side only about the bushing level.
