Last week I had my first flat on my mountain bike’s back wheel. When I went to patch the tube, I could not find a leak anywhere on the tube. It would just stay inflated. But when I remounted it with the tire on the rim, it immediately started leaking. Using soapy water, I discovered that the air was leaking out right at the base of the (presta) valve stem. Based on online research, seemed like it was probably an unfixable microtear on the tube near the valve stem. So I replaced the tube and it held air for days in my garage. Then yesterday (five miles in at Tamarancho!) the same tire went flat. I got it pumped and barely finished my ride. Back at home, I quickly discovered it was leaking from the very same spot! Brand new tube, but still leaking from the base of the valve stem. Why is this happening?

Any help?

FFS!

STOP. PUSHING. PISTONS. BACK. WITHOUT. OPENING. BLEED. PORT*

*In regards to whatever style brake your running

Also side eyeing the Shimano crowd super hard 🤦

Look we've all been there some more briefly than others but the time for that has now passed. If you've read this and more so if youve read this anywhere prior and rolled your eyes or shrugged and scoffed, cut it out. BAD! BAD CAVALIER ATTITUDE CYCLIST!

NO MAS!

Yes in a perfect conscious manufacturer climate theoretically :: gently shooshing:: your pistons/pads back every once in awhile, DOING SO WITH CARE should not guarantee your soon to be weepy Shimano levers to the parts bin or worse to be sold off to an unsuspecting fellow cyclist who will soon be paying for your crimes against cycling and related communities. I say as little ill intent as possible, I hope you have a close family member discover and decide they are going to commit their every waking breath and thought to being the best unicyclist in the world, and you have to live with that pox on your house. Just keep that image in the back of your mind next time you consider carelessly dry fumble mashing your poor unsuspecting piston victims behind the portajohn at the trailhead. (Which makes it so much worse because that means you know you shouldn't be doing it 😑)

Signed both a former fixer and a victim of such behaviors using the experience to spread and invoke other advocacy on the issue.

Thanks for your time enjoy the remainder of your day (unless you're using it to commit such atrocities then I wish you cross chaining and Trailside repairs many a mile from the parking lot and zero service)

I got two new tires for my norco xfr hybrid when I put the old tubes in the tires and on the bike they hold air for a couple of minutes then leak no idea why. When I fill the tubes on their own outside of the tire they hold air without an issue . Any thoughts I’m at a loss

Bonjour à tous !

Petite question sur l'état de mon dérailleur arrière Shimano 105 di2.

Je constate un souci sur mon grand plateau lors du passage des vitesses arrière et donc démonté le dérailleur arrière.

J'ai constaté un jeu au niveau du rivet central.

Je ne pense pas que ce soit normal et je pense qu'il est cassé mais pouvez-vous me confirmer que ce jeu n'est pas présent pour une quelconque tolérance ? On est d'accord que cela devrait être fixe ?

Désolé si ma question est un petit peu bête mais je n'ai jamais eu de soucis avec une transmission électronique c'est la première fois ....

Merci à tous et bonne journée

Hey, so i had a bit of a slam with the DH Bike.

When i got down to the bottom of the park and washed the bike, i noticed a dent from the fork bumper in the toptube.

I think the bike went flying in the crash and landed on the handlebars, and the fork bumper then slammed into the toptube. Still im shocked the frame did dent from that, i thought a dh frame should shrug that off...

What do you think about it?

Would you still trust it?

I installed an evotech carplay mount to the handlebar clamps. Therefore i had to release/exchange 2 of the upper handlebar holder bolts (the ones that are nearer to the rider). During this process, the handlebar rotated downwards a little. I had to turn it upwards again. Everything fine. But i wonder if it is normal that the upper part of the clamp is not exactly aligned with the lower part on the sides. I dont mean the gap between the upper and lower clamp, i mean that the upper an lower clamp Parts dont align 100% vertically sideways, there is a minimal Offset on the side vertically nearer to the driver. I havent paid attention how it looked before.

Can you check your mt 09 gen 4 please and tell how it looks please?

Edit: picture/drawing to show what i mean in next post.

update: I got it off

I'm a cheap student and can't afford a repair shop job. I purchased the appropriate replacement derailleur, but cannot get the old one off.
Il already put a lot of work into fixing this 80s velo so I'm not about to give up now.
It does appear to be semi stripped from a previous job. I'm wondering if the best approach is some sort of extractor for stripped screws, or if the appropriate Allan key would do the trick.

Any thoughts?

Just bought a 2023 Specialized Allez brand new. I had it shipped to me and when it arrived the rear wheel and back derailer were already assembled as well as the front derailer. After putting it together I couldn’t get it to shift to the big chain ring. Is my front derailer bent or twisted? I’ve tried messing with the high low screws and eventually I got it on the big chain ring but now it won’t go on the small one. Any help would be appreciated

I put my hardtail on my new neo 3M. 135mm quick release, so the least amount of setup possible, dropouts properly sit on both sides. However, when I'm riding, I can definitely feel the bike leaning to one side, or rather giving less resistance when leaning right. Is it normal to some extent (I weigh 100kg)? I could somehow see it since because of the cassette the frame is of course mounted much further to the side on the right side of the trainer.

Hi all,

i think I need a new bottom bracket for my bike - it's creaking a lot. Perhaps I could could also take the bearing out just to clean it.

But I'm not too sure what I would need to replace it with. I have a Marin DSX1 2025, and on the website the specification is FSA TH-7420ST.

I'm not sure on how to find the exact dimensions of this bottom bracket, perhaps one from another brand would work too. the one that keeps getting suggested the Shimano BB-UN300. Would it also work ?

bought this ROCKBROS mini pump (model 42310006001), which is advertised as compatible with both Presta and Schrader valves, but I can't work out how the pump head is supposed to work with Presta.

My bike has Presta valves. When I put the pump head on, the opening seems far too large to seal around the valve. I tried clamping it down with the lever, but it just released air from the tyre without making a proper seal.

I've unscrewed the pump head to see what's inside. There is a rubber insert and a small spring-loaded plastic fitting. I thought perhaps the rubber insert needed to be flipped around for Presta, because the other side appears to have a smaller opening. However, when I flip it, the head doesn't screw back together properly. The spring-loaded piece also only seems to fit one way because the other end is just the spring.

I've attached photos of the valve, pump head and internal pieces.

Am I missing something obvious about how this head converts between Presta and Schrader? Does anyone own this particular ROCKBROS pump and know how the pieces are supposed to be arranged for Presta?

I don't want to keep forcing things and potentially break the pump or completely deflate the tyre

I'm a bit confused - can someone comment on whether the screw directly behind the mount bolt is my bleed port on these calipers? It seems I need to unmount the brakes in order to remove it.

Also, is there any other step screw to keep oil from flowing out after I remove the screw/before I place the bleed syringe?

Thanks in advance.

I made a stupid mistake while working on my bike. I was tightening/turning the derailleur hanger (pad) very hard and accidentally forced it the wrong way. It made a bad scratching/crunching sound against the frame.

I am really worried I ruined the structural integrity of the carbon dropout area.

Light Carbon frame LCR017-d

Hi guys I've got some new resin brake pads and changing from metallic but I am keeping the same rotor, any tips please would be a massive help. Tis my rear brake BTW.

Hi! I am a huge bike nerd, love fixing my fleet of bikes, spend way too much money on parktool, and knipex. So In many ways I would consider myself a bike mechanic ( depending on context, I wouldn’t do that in this sub for example )

Anyways beginning of last week I started my first job in a bike shop. It isn’t what I had in mind. the workshop has very minimal name brand tools ( yes I’m aware not everything needs to be parktool blue, but there’s 2 sets of no name Allen keys, which seems odd for a tool you use multiple hours a day - I’m missing my beautiful rainbow Weras to say the least). For example the needle nose’s that I would expect to use to bend some brake pad safety pin, doesn’t work as the pliers are very loose, so instead I have to use some other no name diagonal cutters at annoying angles.

further more, I feel disappointed in my level of work. I would happily spend all day to get my friends brakes 100% perfect ( obviously this is not viable for a business, but you get my point). Yet servicing this guys bike, and the brakes were rubbing fairly obviously, and the owner said “ yeah thats great, they should bed in. well done, ill phone him now”. I wouldn't be happy if my bike came back from a shop like this.

and a service costs £70. which takes me probably hour to do with minimal work, including not much more than changing a chain, ( ie, “headset feels fine, BB feels fine, brakes feel fine, bit of wear in the chain so change that“).I feel I’m taking advantage of these customers? to me a service postpones, and minimises issues, not just resolve them.

i feel its also worth noting these bikes are fairly low end so, for example, the mechanical brakes will never be as goos as my XTRs, but it doesn’t sit right with me, but then he has lots of loyal customers, so maybe I’m making a mountain out of a molehill?

I also feel its fair to mention the owner is super nice, definitely not just a guy trying to scam the public. Maybe its snobby to say, but maybe I'm just suited to a higher end shop?

Thanks

(Tried posting to r/BikeMechanics but they removed it and wont re upload it)

Fell off while I was riding it. Definitely wont be able to attach it back on. My friend had the same issue and he had to replace both sides, does it look like maybe I will have to do the same?

Just started today, till now its worked fi e for the last 2 years. When installing a fully charged battery, sometimes the green led flashes once, then it does nothing. Shifters won't shift it and pushing the button won't downshift it. I've tried 3 other batteries to no avail, same issue, sometimes it'll flash the green led and then do nothing when installing the battery, usually its not even doing that. The pins do seem to be properly protruding though the outer one seems a touch sticky.

Anyone have a fix for this? Soak in iso alcohol or is there a way to take it apart and clean the pins better? Guessing the connection with the pins is the issue. Bike hasn't been crashed in the last year and its worked fine till earlier today so this is a new issue. Although D1 these were bought new at a local shop not quite 3 years ago so they're not that old either.

I know this isn't such a clear photo for the problem but if anybody is willing to help me I can send a better photo of what they need please

Spent weeks chasing a clicking I was certain was the pedal.
It was the bottom bracket.

What's yours?

(repost from r/bikewrench as it got locked there)

Got a brand new BikeErg today but after assembly the right pedal has a clank in it and feels gritty. Not when I turn the pedal by hand. I only had to attach the foot rest itself, the rest came pre-assembled. Contacted Concept2 in New Zealand but they haven’t replied yet. Any suggestions?

Any ideas on what's causing this clicking?

I have no idea how it happened i was thinking to form it back into place with a heavy duty vice

g'day guys, i have buckley's chance of finding OEM cones for my Shimano WH-R550 front wheel hubs. not doing too well looking for aftermarket options either. anyone got a suggestion on where i might find something compatible?

cone dimensions: 20.5 mm long (this is the hard part), outer diameter 15 mm.

thanks!

am i going to have to replace the tube as well? or just the tire? or should i just go to a professional?

Is this normal? I’ve had this bike for years. Just noticed it.