Search found 49 matches

by Tompsk
23 Oct 2019, 7:25am
Forum: Bikes & Bits – Technical section
Topic: Chainline considerations when using triple chainset as double
Replies: 6
Views: 203

Re: Chainline considerations when using triple chainset as double

My preference is to have the chainrings slightly more 'inboard' than 'central'. Reason being is higher chain tension when on the smaller ring for a given pedal push so the chain losses / wear will be worse. This assumes of course that you don't plan to cross the chain on a regular basis! As for bott...
by Tompsk
20 Oct 2019, 9:58pm
Forum: Bikes & Bits – Technical section
Topic: 9 into 7 won't go.....
Replies: 7
Views: 378

Re: 9 into 7 won't go.....

Ditto, 9 of a 10 on a 7 works well too. See Sheldon Brown pages on this topic.
by Tompsk
18 Sep 2019, 9:33pm
Forum: Bikes & Bits – Technical section
Topic: Disc Brake Rotor Torque Ratings?
Replies: 6
Views: 366

Re: Disc Brake Rotor Torque Ratings?

AFAIK the bolts holding on a disc rotor act like pegs with most of the force at 90 degrees to the thread. The torque they are done up to must be sufficient to stop them coming undone and to resist the (comparatively small) forces of the disc moving sideways. NB the bolts holding car and lorry wheels...
by Tompsk
23 Jul 2019, 7:20am
Forum: Bikes & Bits – Technical section
Topic: Bike fit - change from mtb to tourer with drop bars
Replies: 27
Views: 1906

Re: Bike fit - change from mtb to tourer with drop bars

Brake levers seem to be too far from the bars. On the drops behind the brake levers she can only reach the levers with the end of her fingers. On the hoods it's even worse. Looks like the bike industry 'one size fits all' for the brifters (brake & shifters) falls down here. I'm not sure if you ...
by Tompsk
20 Jul 2019, 6:29pm
Forum: Bikes & Bits – Technical section
Topic: wife's triple...difference in mid chain ring distance....
Replies: 7
Views: 298

Re: wife's triple...difference in mid chain ring distance....

Ideally, the middle ring and middle of the cassette align, maybe not too much difference in practice if nothing fouls. I did this with my Spa triple with a 9 speed cassette. I had to get a shorter bottom bracket than recommended and even had to remove a tiny bit of the centre of the driveside chain...
by Tompsk
3 Jan 2018, 6:36pm
Forum: Bikes & Bits – Technical section
Topic: Poor frame design?
Replies: 47
Views: 2266

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: 1544

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: 1544

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: 1544

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: 1665

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: 894

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: 5026

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: 894

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: 894

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: 894

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...