Search found 743 matches

by MikeDee
23 Dec 2020, 9:50pm
Forum: Bikes & Bits – Technical section
Topic: How long do chains & sprockets last ?
Replies: 101
Views: 4672

Re: How long do chains & sprockets last ?

When did roller wear become a "thing"? Old time experts like Jobst Brandt said that roller wear was irrelevant. Now everybody and their brother are jumping on the band wagon concerned about roller wear. Roller clearance is not even a standardized dimension among chain manufacturers as chain pitch is, so how can one even quantify it and say there is too much?
by MikeDee
20 Dec 2020, 4:08pm
Forum: Bikes & Bits – Technical section
Topic: R8020 disc brake Cracked ceramic piston
Replies: 26
Views: 2305

R8020 disc brake Cracked ceramic piston

I wonder how good these pistons and seals are? Probably allow more heat transfer to the brake fluid. What material is in the center of the piston? https://www.ebay.com/itm/Bicycle-Hydrau ... 4453444527
by MikeDee
19 Dec 2020, 4:01pm
Forum: Bikes & Bits – Technical section
Topic: An easy to use track pump head?
Replies: 34
Views: 1748

An easy to use track pump head?

Mick F wrote:Lezyne Airbleed.

The airbleed is for bleeding the pressure from the hose.

Screws on easily.
Pump to required pressure ......... Mercian rear sits at 120psi and Moulton rear at 100psi.
Press the bleed button to release the pressure in the hose only.
Unscrew easily.
Hardly any friction in screwing or unscrewing.

--------------------------------

Told this story before.
I had a track pump some time back and heard all sorts of good news about the Topeak Twinhead. so I bought one and fitted it.
It lighter and easier to use than the original.

Then, I realised something.
It took me a few years before I saw the light.

When you connect up and fill the tyre to nice and hard at 100psi plus, when you release, some air is lost from the tyre.
Repeat a few times connecting, and disconnecting, and slowly you'll end up with a soggy tyre.

Easy to experiment.
Pump to required pressure and remove, then connect a pressure gauge to measure.
Repeat.
You will find that the pressure is now reduced.

Try that with the Lezyne Airbleed, and you'll find no such issue.

Ok, you might say that my Topeak was defective .......... and that's what I thought, so I bought a new set of seals for it. Same issue persisted.

No doubt they are fine at "normal" pressures, but when you want 100psi+, the unit needs to be on firmly so it doesn't blow off. Consequently, the Presta valve is opened a tad so when you disconnect, a bit of air escapes.

So what?
Does it matter?
I mattered to me, so I chucked it away.


That's because it pushes down on the valve stem, unlike the Lezyne. I find if you push it on not too far, it won't crack the valve until the locking lever is applied, and thus you will lose little air. I like this kind of pump head better because you don't have to overcome a sticky valve and you can bleed air from the tire.
by MikeDee
18 Dec 2020, 11:34pm
Forum: Bikes & Bits – Technical section
Topic: How long do chains & sprockets last ?
Replies: 101
Views: 4672

Re: How long do chains & sprockets last ?

OldLimey wrote:
hamish wrote:There's nothing wrong with changing a chain, prematurely, as far as I know, but that's what you get with the Park CC2.


I'm beginning to think that's not so bad, if it saves the cassette and chainrings.
by MikeDee
17 Dec 2020, 5:11pm
Forum: Bikes & Bits – Technical section
Topic: pumps, a list of the good uns based on your findings.
Replies: 148
Views: 6896

Re: pumps, a list of the good uns based on your findings.

Brucey wrote:
MikeDee wrote:

I'm a bit confused as to what threads the connector is screwing on to; the valve stem threads or the ones on the core? .


the core, which is how come cores come unscrewed with some pumps

cheers


I guess it might have to, as some valve stems don't have threads. Still, not a good design in my book. A lot of tubes and tubeless valves have replaceable valve cores these days. As I said, thumb lock for me, push on second place, screw on third...
by MikeDee
17 Dec 2020, 2:17am
Forum: Bikes & Bits – Technical section
Topic: pumps, a list of the good uns based on your findings.
Replies: 148
Views: 6896

pumps, a list of the good uns based on your findings.

Brucey wrote:screw-on connectors only behave consistently in relation to unscrewing removeable (presta) valve cores if the friction between the threaded connector and the valve core remains consistent.

This friction comprises two elements; the load (so the connector should be unscrewed when there is no load on it if possible) and the coefficient of friction between the materials involved.

To my mind the latter is is only likely to be consistent in the long term if the screw-on connector is made from brass. If the screw-on connector is made of aluminium then it is only a matter of time until the anodising wears off the threads and then galling will make the friction against the valve core somewhat variable.

cheers


I'm a bit confused as to what threads the connector is screwing on to; the valve stem threads or the ones on the core? If the valve stem threads, then it can't unscrew the core. Is the gasket bearing down in the core, and when unscrewed, it puts a torque on the valve core to unscrew it? I heard Lezyne put a pressure release button on the pump in later revisions. Is that correct? How does that affect things? Does that mean it doesn't push down on the valve stem so it acts like a Silca push on air chuck? If so, then with a sticky valve stem, it can take a lot of pressure just to crack the valve. Thumb lock types I use push open the valve without relying on the pump differential pressure to do so.
by MikeDee
16 Dec 2020, 6:50pm
Forum: Bikes & Bits – Technical section
Topic: pumps, a list of the good uns based on your findings.
Replies: 148
Views: 6896

Re: pumps, a list of the good uns based on your findings.

pwa wrote:
MikeDee wrote:Don't use a pump that has a screw-on fitting if you have tubes and tubeless valves with removable valve cores, as they can unscrew the valve core on removal. Thumb lock fittings are the best.

Or just make sure the cores are tightly screwed in when you first use the tube, possibly with a pair of pliers. This is only an issue with cores that haven't been screwed in properly. I use screw on pumps and thumb lock pumps and don't have a preference..


Overtightening can tear up the gasket at the bottom of the valve core. I've done it. Use a drop of Loctite and use a proper valve core tool, not pliers.
by MikeDee
16 Dec 2020, 4:22pm
Forum: Bikes & Bits – Technical section
Topic: pumps, a list of the good uns based on your findings.
Replies: 148
Views: 6896

Re: pumps, a list of the good uns based on your findings.

Don't use a pump that has a screw-on fitting if you have tubes and tubeless valves with removable valve cores, as they can unscrew the valve core on removal. Thumb lock fittings are the best.
by MikeDee
12 Dec 2020, 8:28pm
Forum: Bikes & Bits – Technical section
Topic: yet another brake thread; not all about discs
Replies: 111
Views: 5800

Re: yet another brake thread; not all about discs

Herts Audax wrote:Surely you’ll see the lever travel change and need to pull the lever closer to the bar if the hydraulic adjustment runs out? Unless the bite point is really close to the bar (in normal auto adjusting use) that’ll give you warning in time for new pads. It won’t go from effective braking to nothing in the blink of an eye. Plus you’ve two brakes and they are highly unlikely to wear at same rate.


Not really. Lever went to the bar on my mountain bike on a ride due to a slow leak at the caliper piston. No notice beforehand like longer lever travel. Luckily it was the rear brake and I finished the ride with just a front brake. The system makes up for any fluid loss by taking from the reservoir. As soon as the reservoir runs dry, that's it, air in the system.
by MikeDee
8 Dec 2020, 3:25pm
Forum: Bikes & Bits – Technical section
Topic: Where did all the rim eyelets (‘sockets’) go?
Replies: 21
Views: 1489

Where did all the rim eyelets (‘sockets’) go?

I've used a wooden, tapered skewer to hold the spoke nipple and start the threads onto a spoke. Works fairly well. I've also threaded a spoke through the opposite end of the nipple and used it to insert the nipple through the rim. That works, but is more time consuming and starting the thread into the spoke isn't that easy. I bought the Ice Tool but haven't used it yet. You don't need to use the Ice Tool with a drill or electric screwdriver.
by MikeDee
7 Dec 2020, 11:52pm
Forum: Bikes & Bits – Technical section
Topic: Where did all the rim eyelets (‘sockets’) go?
Replies: 21
Views: 1489

Where did all the rim eyelets (‘sockets’) go?

Brucey wrote:this is the business end of the IceToolz 12S4 tool in the video Mike links to above.

Image

The potential problems with such a tool are

- the wire loop will need regular replacement (wear and breakage seem very likely)
- the tool is designed to work with a drill/driver (which means you are wafting several pounds of noisy, heavy, nuisance around, all to set a nipple weighing a fraction of a gramme)
- the tool will be of virtually no value re either full threading or nipple depth setting; it will be pushed out of engagement when the nipple is only a few turns onto the spoke

the last issue means that all the wafting of the heavy noisy tool is pretty much a waste of time; you will have to revisit every spoke with another tool to get the next seven or eight turns on each nipple.

Also the tool end design is not really suitable for use on a nipple driver with a cranked handle (which would be my preferred option, peace and quiet or sounds of my own choosing being my chosen wheelbuilding accompaniment); a cranked handle imposes side loads on the tool and the nipple holding loop is simply not designed with that in mind.

So I'm sure some folk would love that tool but it doesn't quite tick my boxes.

cheers


I would hope that you don't build a wheel where you crank the nipples on to the final position in one fell swoop. You're supposed to improve the spoke tension at low to moderate tension, for example. Using multiple tools is OK by me, as is using a "heavy" electric screwdriver to save time. I'd say this tool with combined with another electric screwdriver bit type tool with a nub that pushes the driver out of the nipple slot as the spoke hits the bottom of the slot would be nice to have for building wheels. I've got a offset hand crank version of a tool like that. https://www.wheelfanatyk.com/blog/wheel ... e-nipples/
by MikeDee
4 Dec 2020, 4:03pm
Forum: Bikes & Bits – Technical section
Topic: Where did all the rim eyelets (‘sockets’) go?
Replies: 21
Views: 1489

Re: Where did all the rim eyelets (‘sockets’) go?

531colin wrote:
Brucey wrote:....Note that if you use a deep-ish rim which doesn't have double eyelets, you are best off using a nipple driver (one which holds the nipple captive) to build the wheel with, else nipples tend to get lost inside the rim (v. annoying).....


I did invent a tool which could pick up a nipple and start it on the spoke thread, all with one hand...long time ago, now...

ImageNipple Picker 060 by 531colin, on Flickr


https://youtu.be/j6FOZEuCCOc
by MikeDee
26 Nov 2020, 5:00pm
Forum: Bikes & Bits – Technical section
Topic: OEM rim tapes that are not good enough.
Replies: 26
Views: 2314

Re: OEM rim tapes that are not good enough.

I like and use Velox, but it soaks up water like a sponge. I live in a dry climate so water in the rims isn't a problem, except on my mountain bike when I rode through streams. I wouldn't use Velox if you get water in the rims.

A lot of people are now using tubeless tape as a rim strip. Not sure I would.
by MikeDee
26 Nov 2020, 1:00am
Forum: Bikes & Bits – Technical section
Topic: OEM rim tapes that are not good enough.
Replies: 26
Views: 2314

Re: OEM rim tapes that are not good enough.

Velox is made of cotton. Cotton doesn't rot?
by MikeDee
25 Nov 2020, 3:22pm
Forum: Bikes & Bits – Technical section
Topic: OEM rim tapes that are not good enough.
Replies: 26
Views: 2314

Re: OEM rim tapes that are not good enough.

Brucey wrote:It seems strong enough, but it isn't, and in addition it rots if it gets wet. And of course it gets wet.

cheers


Velox is a cloth tape, and also rots if it gets wet.