Search found 44 matches

by Tompsk
3 Jan 2018, 6:36pm
Forum: Bikes & Bits – Technical section
Topic: Poor frame design?
Replies: 47
Views: 2201

Re: Poor frame design?

Sounds poor to me. At the 'other end' how is the toe overlap with the front wheel? From memory this was seen as a safety issue but AFAIK the construction rules allow designers to get around this by assuming everone has a tiny shoe size, perhaps they do this at the back too? Not sure if construction ...
by Tompsk
27 Dec 2017, 6:50pm
Forum: Bikes & Bits – Technical section
Topic: It Doesn't matters, It's not the bike/kit you have...
Replies: 27
Views: 1524

Re: It Doesn't matters, It's not the bike/kit you have...

Oh no! It's turned into another gear & chain selection thread!
by Tompsk
27 Dec 2017, 11:28am
Forum: Bikes & Bits – Technical section
Topic: It Doesn't matters, It's not the bike/kit you have...
Replies: 27
Views: 1524

Re: It Doesn't matters, It's not the bike/kit you have...

I'm curious as to whether this is a 7 speed spaced 7 speed or 11speed spaced 7 speed!? From what I've read it's 7 cogs with 11 speed spacing so you can still use your nice new 11 speed shifters. They can only eat so many of their own words in one go. Give it time and they will bring out a high stre...
by Tompsk
26 Dec 2017, 10:34pm
Forum: Bikes & Bits – Technical section
Topic: It Doesn't matters, It's not the bike/kit you have...
Replies: 27
Views: 1524

Re: It Doesn't matters, It's not the bike/kit you have...

Agree with your post but would add reducing tranmission losses by using a bit of lube and replace drive train components when worn. This isn't rocket science and wont keep the marketing people in employment so they come up with all sorts of reasons for you to spend your money. The latest I saw (I je...
by Tompsk
16 Dec 2017, 3:35pm
Forum: Bikes & Bits – Technical section
Topic: Excess price rise(s)?
Replies: 24
Views: 1638

Excess price rise(s)?

Been musing about buying the following tyres. I'd swear these were £8 a week or so ago (not on a special offer), now listed at £12 each - I can't think what justifies a +50% price rise... http://www.wiggle.co.uk/lifeline-essential-road-tyre/ http://www.wiggle.co.uk/lifeline-essential-commuter-road-t...
by Tompsk
6 Dec 2017, 9:01pm
Forum: Bikes & Bits – Technical section
Topic: Seatpost: how loose is acceptable? - Solved
Replies: 8
Views: 878

Re: Seatpost: how loose is acceptable? - Solved

I've now solved the problem (spending an unnecessary extra £20 on my "buy a frame and build a bike from the spares box" project) by buying a 25mm post and a 25 to 27.4mm shim, both from SJS. The shim is sprung wide and so a very tight fit in the tube - not sure if that is going to come out...
by Tompsk
3 Dec 2017, 7:12pm
Forum: Racing, Olympics, TdF, Competitive cycling
Topic: pre STI shifters for racing
Replies: 16
Views: 4958

Re: pre STI shifters for racing

My experience and comments on the 3 systems: STi / Ergo / Tap needs different cable outers so the pull does not change when the handlebars are turned, if using brake cable outers there is a small change in length which leads to the mech moving slightly. This probably didn't matter with 5 speeds, but...
by Tompsk
25 Nov 2017, 12:10pm
Forum: Bikes & Bits – Technical section
Topic: Seatpost: how loose is acceptable? - Solved
Replies: 8
Views: 878

Re: Seatpost: how loose is acceptable?

Well I've just measured everything up with a digital vernier: The "27.2mm" seat post is a very consistent 27.15mm wherever I measure along its length - so there or there abouts on specification. The "27.2mm" seat tube internal diameter is actually 27.45mm all around - at least fo...
by Tompsk
19 Nov 2017, 10:56pm
Forum: Bikes & Bits – Technical section
Topic: Seatpost: how loose is acceptable? - Solved
Replies: 8
Views: 878

Re: Seatpost: how loose is acceptable?

Yes, they should be a snug fit. I'm a bit confused by your proposal to get a smaller-diameter post though, because you appear to need a larger one? You're correct that the Radial site says that you need a 27.2mm post . That's odd, because that's the standard size for 531DB steel tubing. I'd have th...
by Tompsk
19 Nov 2017, 6:13pm
Forum: Bikes & Bits – Technical section
Topic: Seatpost: how loose is acceptable? - Solved
Replies: 8
Views: 878

Seatpost: how loose is acceptable? - Solved

I bought a new aluminium frame: https://www.radialcycles.co.uk/bikes/framesets/revere-1-1-radial-alloy-frame.html This states "Seat post size 27.2", however when I insert the correct sized post: https://www.ribblecycles.co.uk/system-ex-seatpillar/#pid=22919 It is a very loose fit. After in...
by Tompsk
13 Nov 2017, 1:30pm
Forum: Bikes & Bits – Technical section
Topic: What's This Tab For?
Replies: 45
Views: 2154

Re: What's This Tab For?

I had something vaguely similar once, are you 100% sure you have threaded the chain through the cage correctly? - I missed this once, fortunately I spotted it before I took the bike out.
by Tompsk
17 Oct 2017, 9:53pm
Forum: Bikes & Bits – Technical section
Topic: Chain harmonics - what does this mean?
Replies: 29
Views: 1507

Re: Chain harmonics - what does this mean?

I saw that too and was wondering what is meant by that. My only (big) guess is that having a prime number in the mix would mean that the chain would not keep lining up with the same links on the same teeth. However I think this is only true if the number of links in the chain is a prime number as th...
by Tompsk
4 Oct 2017, 9:45pm
Forum: Bikes & Bits – Technical section
Topic: Internal Di2 Battery Charging - Electronics Help!
Replies: 11
Views: 1382

Re: Internal Di2 Battery Charging - Electronics Help!

Lithium Ion batteries are not easy to charge safely so I would ditch the Lithium Ion battery and use a PP3 rechargeable (about 8.4V from memory) and charge this from the dynohub via a diode and suitable resistor. The 7V or so can be created from the PP3 using an LM317 regulator to power the Di syste...
by Tompsk
2 Oct 2017, 8:44pm
Forum: Bikes & Bits – Technical section
Topic: Gearing : resolving the 17t - 20t sprocket jump
Replies: 29
Views: 1593

Re: Gearing Yes yet again.

fredN4 wrote:22/34! quicker to get off and push it? :D


Perhaps, but nowhere near as easy to push a bike uphill than ride it.
by Tompsk
24 Sep 2017, 10:36pm
Forum: Bikes & Bits – Technical section
Topic: Digital wireless bike speedo
Replies: 11
Views: 626

Re: Digital wireless bike speedo

There are reports of some LED headlights messing up wireless bike computers. I think the low power mode switches on and off the LED at high frequency to make it appear dimmer, without wasting energy in a dropper resistor. This high frequency switching may interfere with the wireless communication. I...