Search found 687 matches

by bgnukem
7 Jul 2022, 5:59pm
Forum: Bikes & Bits – Technical section
Topic: Gear Question
Replies: 13
Views: 609

Re: Gear Question

Ditto the above, I leave my bikes in a suitable gear to set off, usually halfway along the cassette.

I've left bikes like that for literally years and then ridden them normally with no issues.

The idea of a spring, derailleur or otherwise, is that the steel remains within it's elastic strain range and does not reach the yield point, therefore it should keep working fine as a spring as long as the tension does not cause yield, e.g. through operating beyond design parameters / normal range of movement for a rear mech. Also assuming the spring does not corrode, of course.
by bgnukem
5 Jul 2022, 4:02pm
Forum: Bikes & Bits – Technical section
Topic: Tyres without direction indicators - which way round? And 40 PSI max?!
Replies: 24
Views: 991

Re: Tyres without direction indicators - which way round? And 40 PSI max?!

531colin wrote: 5 Jul 2022, 2:23pm Has anybody ever found it makes any difference at all which way you mount tyres which DO have "direction arrows"?
I have never found any difference at all; I suspect that (like "dropped seatstays" and a lot of bicycle "design") the feature is there just to make you think somebody has thought about it.
Think it might make a difference for knobblies off road. I remember Panracer used to make different front and rear tread patterns and I can image that on soft surfaces the knobbles or patterns of knobbles might be optimised directionally, e.g. for drive at the rear tyre, or lateral grip at the front.

For road use I've never noticed any difference, and sometimes I rotate tyres side to side on the rims to even out the offset wear pattern caused by road camber. Certainly bikes don't go fast enough for water clearance / aquaplaning to be an issue, unlike car tyres.
by bgnukem
5 Jul 2022, 12:17pm
Forum: Bikes & Bits – Technical section
Topic: Frame crack on folding bike
Replies: 15
Views: 1449

Re: Frame crack on folding bike

The crack has extended around roughly half of the seat tube circumference, which would be the half placed in tension by the bending force applied by the seat post, so I think the crack may not extend much further. Drilling small holes through the ends of the crack to stop further propagation, as Colin suggested, might be a good idea. Be careful that the ends of the crack may be beyond the visible rust / paint cracking so use a magnifier to check and perhaps polish up the area with some emery paper.

You would want to check that the crack does not continue to propagate. The seat post itself should help to hold things together in the worst case scenario that cracking continued further around the circumference of the seat tube, but if the crack encircles the seat tube and/or reaches the seat stays then I'd scrap or repair the frame.
by bgnukem
5 Jul 2022, 11:50am
Forum: Bikes & Bits – Technical section
Topic: I hate disc brakes - help!
Replies: 108
Views: 9263

Re: I hate disc brakes - help!

As a total luddite who has stuck with 8/9-speed transmissions, triple chainsets, square taper bottom brackets, QR axles, and all sorts of other unfashionable yet fit-for-purpose 'tech', I have to admit I like my hydraulic discs for the following reasons:

i) Smoother braking / better modulation
ii) Not wearing out rims every couple of winters, as they are so soft and have such thin sidewalls these days.
iii) Not having to constantly clean rims and clean out bits of grit and aluminium from the brake pads in order to try to avoid (ii)

:but I hate disc brakes because of the stiff forks required to mount them, which makes for more shock through the bars on the UK's joke 'road' surfaces.

Never had fade yet, but I've not gone loaded touring with them in very hilly places.

I also admit that cable discs were a faff, and kept rubbing every time the wheel/s were removed and refitted. Had fade once on a hottish day on gravel roads in NZ, where fairly constant braking was needed to keep the speed down, with the cable discs but not total failure. Just stopped and waited for things to cool off a bit.
by bgnukem
30 Jun 2022, 12:49pm
Forum: Bikes & Bits – Technical section
Topic: Head says steel, heart says titanium
Replies: 65
Views: 4767

Re: Head says steel, heart says titanium

Jupestar wrote: 30 Jun 2022, 12:29pm
mig wrote: 30 Jun 2022, 11:23am what's the issue with making a front fork out of titanium? rarely, if ever seems to occur.
certainly no expert but was once told Ti is too flexible for forks. There is a few. but to get the stiffness you need big tubes.
Yes, the Young's Modulus / Modulus of Elasticity of the common Ti alloys (Ti-6Al-4V and Ti-3Al-2.5V) is around 107 - 114GPa compared to around 190 - 200GPa for steel. You'd need much bigger diameter fork legs and/or thicker walls to equal the stiffness of a steel fork.

My guess is it would look to clunky and might put off buyers, while not saving any significant weight vs a steel fork and being way heavier than a C fork.

Plus, C forks are cheaply available off the peg so a framebuilder can design their frame geometry to suit, and save a chunk of money on the bike/frameset.
by bgnukem
30 Jun 2022, 12:43pm
Forum: Bikes & Bits – Technical section
Topic: In praise of bike boingy bits.
Replies: 15
Views: 1028

Re: In praise of bike boingy bits.

I also have a Thudbuster ST (short travel) on one of my bikes, and it definitely moves during normal riding, with visible 'droop' just sitting in the saddle. Certainly seems a better idea than a telescopic post where the bending force on the seatpost might cause stiction in the sliding motion.

Don't notice the movement as wasted energy when climbing either. Recommended.
by bgnukem
30 Jun 2022, 11:07am
Forum: Bikes & Bits – Technical section
Topic: Bottle Dynamos
Replies: 89
Views: 5165

Re: Bottle Dynamos

Very draggy, bit noisy, rubber wheels can slip in the wet without a tyre with a sidewall track for such a wheel. OK for shortish utility trips I guess but a basic Shimano dynohub neednt cost much and easily outperforms a bottle.

Think I used an AXA bottle for a few years of commuting before I saw the light (groan!) and started using a series of hubs. Only thing I'd say is adjust the hub bearings properly before use - the Shimano hubs are always set too tight.
by bgnukem
30 Jun 2022, 11:04am
Forum: Bikes & Bits – Technical section
Topic: In praise of bike boingy bits.
Replies: 15
Views: 1028

Re: In praise of bike boingy bits.

I'm quite interested in those Redshift suspension stems. Getting fed up of my hands taking a battering from stiff front forks designed for disc brakes, plus lousy road surfaces, and that is using 32mm (700C) / 1.3" (26") tyres as well......
by bgnukem
30 Jun 2022, 11:01am
Forum: Bikes & Bits – Technical section
Topic: chain lube or wax?
Replies: 76
Views: 4665

Re: chain lube or wax?

NickJP wrote: 28 Jun 2022, 9:51pm
bgnukem wrote: 28 Jun 2022, 10:25am I religiously clean mine after every long ride and weekly when commuting, also using FL wet, and typically swap chains at 0.5% after maybe 1500 miles!
That seems rather low. If you look at the chain test here: https://cyclingtips.com/2019/12/the-bes ... cy-tested/, where chains were deliberately run lubricated with a slightly gritty mixture to accelerate wear, the best chains lasted about 3500km to 0.5% elongation. Note that if you're measuring wear with a chain checker that uses the rollers, then with some chains those checkers will show 0.5% wear at only about half the distance of the elongation measurement. I also found it interesting in that test that chain life increases with the skinnier chains - about three quarters of the way through the article they have a graph showing the longevity of 8/9/10/11/12-speed Shimano chains, and the 12-speed lasts the longest and the 8-speed the least.

As for which chains we use, they're a mixture - between my wife and myself we have a lot of bikes, and the chains are Shimano, SRAM, Wipperman, KMC, and one bike with Campagnolo 10-speed is running Campagnolo chains.
Use mainly SRAM myself, but not the highest quality or cheapest. I'm sure the chain checker is over-estimating wear by including roller wear twice. The chains are not discarded after 1500 miles but kept and used again later, usually up to 3 times each as everything else gradually wears out. I use long front mudflaps as I find all front mudguards are far too short to stop front wheel crud going directly onto the chainset/bottom bracket.

Odd that the skinny newer chains last longer, but I guess better materials may have been specified to offset the higher stresses inside the chains, or just that the lesser speed equipment generally is now at the lower end of the market and quality has decreased (including the chains)?

I'm sticking with 8-speed on most of my bikes, with 9-speed on a couple.
by bgnukem
28 Jun 2022, 10:27am
Forum: Bikes & Bits – Technical section
Topic: SON hub choice question
Replies: 16
Views: 1114

Re: SON hub choice question

Use a centre-lock to 6-bolt adaptor?
by bgnukem
28 Jun 2022, 10:25am
Forum: Bikes & Bits – Technical section
Topic: chain lube or wax?
Replies: 76
Views: 4665

Re: chain lube or wax?

NickJP wrote: 28 Jun 2022, 3:54am ..... I generally get at least 10000km out of a chain before it has got to 0.5% elongation, and a cassette lasts about three chains before the most used teeth on it start to look like hooks.
10,000kms for 0.5% wear! Care to share which chain/s you are using??

I religiously clean mine after every long ride and weekly when commuting, also using FL wet, and typically swap chains at 0.5% after maybe 1500 miles!
by bgnukem
27 Jun 2022, 12:48pm
Forum: Bikes & Bits – Technical section
Topic: chain lube or wax?
Replies: 76
Views: 4665

Re: chain lube or wax?

Don't have much faith in wax as it does not remain fluid and so if it is forced out of the high-pressure contact areas within the chain (inner side plate - to - link pin and rollers - to - inner side plate contacts) by pressure and/or link movements, it cannot re-enter these contacts and lubricate properly.

OTOH, wet lubes attract dirt and create grinding paste inside the links.

Has anyone compared chain wear vs. mileage for chain wax vs. chain oil?
by bgnukem
27 Jun 2022, 11:26am
Forum: Bikes & Bits – Technical section
Topic: Help buying new wheels
Replies: 16
Views: 787

Re: Help buying new wheels

DCR wheels built me some decent wheels with deep section Kinlin rims, 28 spokes and their own brand 6-bolt disc hubs. Covered an estimated 4-5k miles so far in the last year and they've proved durable and not needed truing. Came in at £400 but cheaper builds are available. The website has plenty of useful information on rims and hubs etc.
by bgnukem
23 Jun 2022, 1:06pm
Forum: Bikes & Bits – Technical section
Topic: Finding the right saddle
Replies: 26
Views: 1334

Re: Finding the right saddle

Charge Pan works for me, now have them on all my bikes.

Tried the Spoon but found it too narrow, though it seems to work for many people. Have also worked through Brooks B17 and B17 Champion Special (both stretched too quickly and the sides splayed out), Spa leather saddle (too hard and didn't break in), Rolls (widely recommended but I found it way too hard), Specialized body geometry (excruciating, rode it once only), in the past.

I remember 'Bodyfit' (?) saddles having a fitting system which basically consisted of asking someone to sit on a piece of corrugated cardboard placed on a hard surface in order to measure the width of the indentations left by their sit bones, then recommending a saddle of suitable width to ensure the sit bones rested on the saddle pads. Seemed like a sensible way to identify saddles of suitable width for one's behind......
by bgnukem
23 Jun 2022, 12:14pm
Forum: Bikes & Bits – Technical section
Topic: Chain slipping Between Chainrings
Replies: 82
Views: 2951

Re: Chain slipping Between Chainrings

I had a similar issue with a basic version of the Spa triple, i.e. the one with two steel rings fitted (inner and middle), in that a 9-speed chain would fall into the gap between the big and middle rings.

This was resolved by machining some material off the spider (and granny ring bosses) to bring the rings closer together. Oddly, I am running the same chainset but with Spa aluminium alloy rings on another bike with 9-speed without issues.

I suspect either quality control variations or that the steel rings were thinner than the ali rings, but I think the triples are based on the old Sugino XD2 cranks and so perhaps were designed for 7/8-speed chains.