Search found 984 matches

by BigG
2 Oct 2017, 8:48pm
Forum: Bikes & Bits – Technical section
Topic: Gearing : resolving the 17t - 20t sprocket jump
Replies: 29
Views: 1618

Re: Gearing Yes yet again.

22/34! quicker to get off and push it? :D No it isn't! Even my 22/38 gear (15.6") gives a speed of 3.25 mph at a comfortable cadence of 70. Bearing in mind that this is only used going up a very steep hill. reaching that speed while pushing a bike is much more difficult than continuing to ride...
by BigG
30 Sep 2017, 5:52pm
Forum: Bikes & Bits – Technical section
Topic: Maiden Voyage On 29er Very Confused?
Replies: 40
Views: 1651

Re: Maiden Voyage On 29er Very Confused?

A 770C wheel with a 25-622 tyre has a rolling diameter of about 672 mm depending a little on tyre pressure, rider weight and the individual manufacturer's tyre carcase design. A typical mountain bike wheel (559 mm rim diameter) has a rolling diameter of about 660 mm with a nominal 2" tyre subje...
by BigG
22 Sep 2017, 8:19pm
Forum: Bikes & Bits – Technical section
Topic: 21 Gears - How Come Only Four Have Any Purpose?
Replies: 35
Views: 2068

Re: 21 Gears - How Come Only Four Have Any Purpose?

MickF is right about the coast roads. These cross every river at about sea level and climb every headland in between. My first long tour was from London to Penzance and back in 1954 with Southampton to Penzance along the south coast and back along the north coast to Bath and Oxford. A 4 speed Simple...
by BigG
13 Sep 2017, 9:32pm
Forum: Bikes & Bits – Technical section
Topic: Deore XT old and new
Replies: 13
Views: 894

Re: Deore XT old and new

You may find the old XT 761SGS (the pre shadow model) or the cheaper and almost indistinguishable LX 661SGS would suit you better than more modern versions. The older ones are in my experience more rugged and function just as well up to 9 speed. They are fairly readily available on ebay. They have t...
by BigG
11 Sep 2017, 5:09pm
Forum: Bikes & Bits – Technical section
Topic: Pedals, and precession
Replies: 10
Views: 686

Re: Pedals, and precession

I cannot let Brucey's comment above about precession on pedal spindles go without comment. On this very rare occasion, I regret to say that Brucey is wrong. Precession works in the same direction at each end of the pedal spindle exactly as it does on the bottom bracket cups. The difference between t...
by BigG
6 Sep 2017, 10:38pm
Forum: Bikes & Bits – Technical section
Topic: downgrading with age.
Replies: 82
Views: 3707

Re: downgrading with age.

The greatest advance of all time was probably the ball bearing, closely followed by the pnuematic tyre. In my cycling life, however (I am 79) the advance that has given me the greatest benefit is the square taper bottom bracket. I still remember the hours spent trying to remove worn cotter pins and ...
by BigG
6 Sep 2017, 10:29pm
Forum: Bikes & Bits – Technical section
Topic: Rebuild -Front derailleur advice needed
Replies: 28
Views: 1314

Re: Rebuild -Front derailleur advice needed

The only part of the outer plate of a front mech that does anything useful when changing down from the big ring is the section adjacent to the main mechanism. It only has to derail the chain at that point which (in my experience) is a simple task that requires no particular accuracy of shape or posi...
by BigG
30 Jul 2017, 10:36pm
Forum: Bikes & Bits – Technical section
Topic: New Build - Gearing Options
Replies: 46
Views: 1866

Re: New Build - Gearing Options

Taking Brucey's suggestion but using a 48 tooth outer ring would give (IMO) marginally better ratios and should work well enough with the mechs specified. Try it out on the Gear Calculator link on Brucey's post.
by BigG
26 Jul 2017, 5:21pm
Forum: Bikes & Bits – Technical section
Topic: Rear brake adjustment screw for cantis
Replies: 15
Views: 739

Re: Rear brake adjustment screw for cantis

I had the same problem on an old Holdsworth frame. I purchased on ebay a brake hanger complete with adjuster that hangs from the seat post bolt. This not only gave me the adjuster but provided a very much stiffer cable termination providing much better braking. The old cable mount bent visibly under...
by BigG
23 Jul 2017, 12:56pm
Forum: Does anyone know … ?
Topic: ...if there is any advantage to reversing the chain?
Replies: 28
Views: 1440

Re: ...if there is any advantage to reversing the chain?

MickF is right. Keep it clean and change when necessary. Any extra mileage available from turning a chain (if any exists at all) is only going to yield the cost of a few cups of coffee. Use good mid-range chains (KMC is my current choice - without any fancy chrome links). Wear on sprockets and chain...
by BigG
22 Jul 2017, 5:21pm
Forum: Does anyone know … ?
Topic: Fueltank XL extra large bottle cage
Replies: 14
Views: 1517

Re: Fueltank XL extra large bottle cage

I have three different ones which I bought locally and I think are still available. The Topeak and Minoura are both designed to take standard 1.5 litre water bottles. The rubber retaining strap at the bottle neck on the Topeak did not last long, but was easily replaced by a flexible tie. The Minoura...
by BigG
4 Jul 2017, 9:48pm
Forum: Does anyone know … ?
Topic: Asymmetric front/rear tyres?
Replies: 98
Views: 5570

Re: Asymmetric front/rear tyres?

I used 28 mm tyres on the front and 32s on the back for several years. It seemed sensible with my 32/40 spoke count. Both tyres were pumped to the same pressure. More recently, I have reverted to the same tyre back and front. I run the front about 1 bar lower pressure than the back. I cannot tell th...
by BigG
30 Jun 2017, 9:47pm
Forum: Bikes & Bits – Technical section
Topic: Unequivocal chain wear measurement?
Replies: 16
Views: 1968

Re: Unequivocal chain wear measurement?

I have a new chain hanging on a nail in the shed. I hang my used chain after cleaning from the same nail. This gives a good visual indication of chain stretch and indicates when I need to change it. :D You could even hang a worn chain up and use this as a reference to compare with a used chain to i...
by BigG
8 Jun 2017, 8:00pm
Forum: Bikes & Bits – Technical section
Topic: Copying MTB gear range on tourer
Replies: 38
Views: 3157

Re: Copying MTB gear range on tourer

My experience is that toe-clip overlap (I still use them) or any system which allows a clipped-in shoe to contact and impede the turning of the front wheel must be avoided with very low gears. Such low gears imply very low speeds up steep hills, probably 3 mph or less. Maintaining balance in these c...
by BigG
5 Jun 2017, 3:34pm
Forum: Bikes & Bits – Technical section
Topic: Chain wear, just reassure me.
Replies: 55
Views: 10091

Re: Chain wear, just reassure me.

Chain length extension can be measured very easily and accurately without any of the compromises and complications when using a proprietary gauge over a short length of chain. Modern quick links make it easy to remove the chain from the bike. I then hang the last link from a nail on my garage door j...