Mechanics Quick Question Thread [Ask Questions Here]

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Mechanics Quick Question Thread [Ask Questions Here]
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Posted: Sep 10, 2019 at 9:01 Quote
just installed new Shimano XT 4 piston brake set. The brake pads rattle badly when not under braking. Obviously not felt when climbing, but when descending even at slow speeds they rattle. Vibrations are felt through the entire bike and its very noisy and uncomfortable. Under braking everything is silent and works really well. Any ideas why my pads rattle so bad ?

Posted: Sep 10, 2019 at 9:10 Quote
I will be replacing the bearings on my Diamondback catch and are there certain types of bearing? I have never done this before.

Posted: Sep 10, 2019 at 9:50 Quote
hyroller80 wrote:
just installed new Shimano XT 4 piston brake set. The brake pads rattle badly when not under braking. Obviously not felt when climbing, but when descending even at slow speeds they rattle. Vibrations are felt through the entire bike and its very noisy and uncomfortable. Under braking everything is silent and works really well. Any ideas why my pads rattle so bad ?

Try spreading out the pad spring a little. If these are Ice tec pads (with the heat sink fins), you can also try wrapping a small elastic band at the base of the fin of each pad to mute the noise as the fin rattles back and forth on top of the brake pad slot. This elastic band trick isn't a sure shot so you might have to get non ice tec pads to totally solve the rattle.

Posted: Sep 10, 2019 at 10:00 Quote
sangier wrote:
I will be replacing the bearings on my Diamondback catch and are there certain types of bearing? I have never done this before.
just google for Diamondback catch bearing kit. Every bike model has different measurements for the bearings, but make sure it is the 'full complement' type. This type of bearing is better at handling the type of loads of a linkage system. You also need a bearing press, bearing puller, and adapters to replace the bearings. These tools are not cheap and you can easily wreck your frame if you press in the bearings not perfectly straight. So I would say take it to a bike shop, or try a bearing press on some old bike first.

Posted: Sep 10, 2019 at 10:03 Quote
sangier wrote:
I will be replacing the bearings on my Diamondback catch and are there certain types of bearing? I have never done this before.

Couldn't find an exploded view of the Catch with bearing sizes listed but it looks like RWS has a bearing kit available online with shockingly little detail on what it contains. I'd follow up with DB and RWC and see if they can clarify bearing counts and dimensions before pulling the trigger on the kit.

https://www.enduroforkseals.com/products/rear-suspension/suspension-pivot-bearing-kits/SBKDB5A.html

PS, you'll need specialized tools to pull/press bearings so think of that when you're evaluating the cost/benefit ratio of having a shop do it. As mentioned above, bodging it with hammer/punch/woodblocks increases the odds of bad things.

Posted: Sep 10, 2019 at 10:35 Quote
R-M-R wrote:
jamieridesbikes wrote:
Don't have on to measure, I also don't know if it's course or fine, M6, M7, M8, M9 or M10.
I've already tried Google, Shimano tech docs etc

Okay, fine, since you don't have one to measure and I was snippy about it, I'll go to my garage and measure ...

If we're talking about the BH90 / BH59 Hose Connecting Screw, it's M8, fine thread. If you need additional measurements for hose connections, look at post #6 in this thread.
Cheers man, appreciate it!

Posted: Sep 10, 2019 at 16:06 Quote
I came off my bike a few months back and my front brake lost all its fluid. I have just taken it in to my local shop thinking they'd just have to replace pads, bleed it etc. But they said they may have to replace the front disc as the fluid has been sat on there a while. is this right? Can the disc just be cleaned?

Posted: Sep 10, 2019 at 16:13 Quote
tomsx144 wrote:
I came off my bike a few months back and my front brake lost all its fluid. I have just taken it in to my local shop thinking they'd just have to replace pads, bleed it etc. But they said they may have to replace the front disc as the fluid has been sat on there a while. is this right? Can the disc just be cleaned?

The rotor can be cleaned. Start with dish soap and very hot water, then acetone or acetone-based nail polish remover, if you don't want to bother finding pure acetone. Wipe it thoroughly with acetone a few times or even soak it in a shallow pan (covered to minimize evaporation and fumes) before the first wipe. Finally, you can blow-torch it to burn of anything that's left, if you like, but it's probably fine by this point.

Posted: Sep 10, 2019 at 16:46 Quote
freestyIAM wrote:
sangier wrote:
I will be replacing the bearings on my Diamondback catch and are there certain types of bearing? I have never done this before.

Couldn't find an exploded view of the Catch with bearing sizes listed but it looks like RWS has a bearing kit available online with shockingly little detail on what it contains. I'd follow up with DB and RWC and see if they can clarify bearing counts and dimensions before pulling the trigger on the kit.

https://www.enduroforkseals.com/products/rear-suspension/suspension-pivot-bearing-kits/SBKDB5A.html

PS, you'll need specialized tools to pull/press bearings so think of that when you're evaluating the cost/benefit ratio of having a shop do it. As mentioned above, bodging it with hammer/punch/woodblocks increases the odds of bad things.

Thanks, DB has not replied to my question so I went to PB. I think the website you showed me should work, but will email DB again. My mtb club just got sponsored by a bike shop, so I got free tools and service which is pretty nice.

Posted: Sep 10, 2019 at 17:30 Quote
I'm planning to get an ellipitcal chainring soon, and I recall hearing that you either want to go up or down 2T to get similar power/feel as a regular circular chainring. Anyone have any insight into this?

Posted: Sep 10, 2019 at 17:33 Quote
R-M-R wrote:
tomsx144 wrote:
I came off my bike a few months back and my front brake lost all its fluid. I have just taken it in to my local shop thinking they'd just have to replace pads, bleed it etc. But they said they may have to replace the front disc as the fluid has been sat on there a while. is this right? Can the disc just be cleaned?

The rotor can be cleaned. Start with dish soap and very hot water, then acetone or acetone-based nail polish remover, if you don't want to bother finding pure acetone. Wipe it thoroughly with acetone a few times or even soak it in a shallow pan (covered to minimize evaporation and fumes) before the first wipe. Finally, you can blow-torch it to burn of anything that's left, if you like, but it's probably fine by this point.
Many shops won't clean contaminated rotors for two reasons:

1: It doesn't always work well, depending on how much it was ridden while contaminated and what it was contaminated with. The shop can't guarantee that the problem is 100% fixed. I wouldn't want to charge a customer without knowing I had fixed the problem the paid me to.

2: Its usually time consuming, no big deal if you're a home mechanic. If you're a shop, it either eats up your already mediocre profit margins or it costs the customer almost the same as a new rotor.

Reason 1 combined with Reason 2 means it's usually better to just replace the rotor. Just take the old rotor home, clean it yourself and keep it as a spare.

Posted: Sep 10, 2019 at 19:59 Quote
Nobble wrote:
R-M-R wrote:
tomsx144 wrote:
I came off my bike a few months back and my front brake lost all its fluid. I have just taken it in to my local shop thinking they'd just have to replace pads, bleed it etc. But they said they may have to replace the front disc as the fluid has been sat on there a while. is this right? Can the disc just be cleaned?

The rotor can be cleaned. Start with dish soap and very hot water, then acetone or acetone-based nail polish remover, if you don't want to bother finding pure acetone. Wipe it thoroughly with acetone a few times or even soak it in a shallow pan (covered to minimize evaporation and fumes) before the first wipe. Finally, you can blow-torch it to burn of anything that's left, if you like, but it's probably fine by this point.
Many shops won't clean contaminated rotors for two reasons:

1: It doesn't always work well, depending on how much it was ridden while contaminated and what it was contaminated with. The shop can't guarantee that the problem is 100% fixed. I wouldn't want to charge a customer without knowing I had fixed the problem the paid me to.

2: Its usually time consuming, no big deal if you're a home mechanic. If you're a shop, it either eats up your already mediocre profit margins or it costs the customer almost the same as a new rotor.

Reason 1 combined with Reason 2 means it's usually better to just replace the rotor. Just take the old rotor home, clean it yourself and keep it as a spare.
Automotive disc brake cleaner that is residue free works perfectly. Has never let me down. My favorite brand is berrymans. I've even had success cleaning contaminated pads with if they're not completely soaked. As far as from a shop stands, I agree. It's best not to leave something, like brakes especially, to chance and end up with an unhappy customer.

Posted: Sep 10, 2019 at 21:11 Quote
Duderz7 wrote:
Nobble wrote:
R-M-R wrote:


The rotor can be cleaned. Start with dish soap and very hot water, then acetone or acetone-based nail polish remover, if you don't want to bother finding pure acetone. Wipe it thoroughly with acetone a few times or even soak it in a shallow pan (covered to minimize evaporation and fumes) before the first wipe. Finally, you can blow-torch it to burn of anything that's left, if you like, but it's probably fine by this point.
Many shops won't clean contaminated rotors for two reasons:

1: It doesn't always work well, depending on how much it was ridden while contaminated and what it was contaminated with. The shop can't guarantee that the problem is 100% fixed. I wouldn't want to charge a customer without knowing I had fixed the problem the paid me to.

2: Its usually time consuming, no big deal if you're a home mechanic. If you're a shop, it either eats up your already mediocre profit margins or it costs the customer almost the same as a new rotor.

Reason 1 combined with Reason 2 means it's usually better to just replace the rotor. Just take the old rotor home, clean it yourself and keep it as a spare.
Automotive disc brake cleaner that is residue free works perfectly. Has never let me down. My favorite brand is berrymans. I've even had success cleaning contaminated pads with if they're not completely soaked. As far as from a shop stands, I agree. It's best not to leave something, like brakes especially, to chance and end up with an unhappy customer.

Here's the MSDS for Berryman Brake Cleaner: it's 95% - 99% acetone!

Posted: Sep 10, 2019 at 22:06 Quote
coaster156 wrote:
I'm planning to get an ellipitcal chainring soon, and I recall hearing that you either want to go up or down 2T to get similar power/feel as a regular circular chainring. Anyone have any insight into this?

Yes, exactly this a 36 feels like a 38. A bit of adjustment to your pedalling/gearing at first but, they definitely put out more, smoother power so you need to be up a cog

P.S I have read that Absolute Black have the perfect shape patented, not sure how true that is

Posted: Sep 10, 2019 at 22:13 Quote
nojzilla wrote:
I have read that Absolute Black have the perfect shape patented, not sure how true that is

As true as the perfect saddle shape, shoe fit, or flavour of ice cream.

Think of it this way: we still debate whether oval is better than round in the first place. If we can't decide which is better between such different shapes, it's a wild exaggeration to suggest some tiny variation of oval is perfect.


 
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