Search found 67 matches

by Raleigh Steve
13 Dec 2010, 6:24pm
Forum: Bikes & Bits – Technical section
Topic: Touring versus racing bike - for commuting
Replies: 197
Views: 15312

Re: Touring versus racing bike - for commuting

Interesting! In theory I guess you would expect the weight to make a bigger difference on such a hilly ride. The work performed in climbing with each bike is as follows:

Rider = 76kg
Carbon bike = 9.5kg
Total weight = 855N

Work = 855N x 843M = 720,765J

Assuming 170W as his average power, he spent 4,239 seconds climbing on the carbon bike: 1:10:39

On the steel bike his total weight was 895N

895N x 843M = 754,485J

So for the same power he spent 4,438 seconds climbing on the steel bike: 1:13:58.

So 3:19 diference, less if that power figure is a bit pessimistic. I think even that is surprisingly small! Goes to show cycling is more complicated that you might think!

I wouldn't be surprised if the touring bike had lower rolling resistance (especially given the unsurfaced bit), which would knock a bit off. Did he have this study in mind and favour the steel bike with extra power? Greater comfort must help produce closer to his optimal power.

Maybe he should have bought a two grand bike! :D
by Raleigh Steve
7 Dec 2010, 8:03pm
Forum: Bikes & Bits – Technical section
Topic: Trials Bike Transmission
Replies: 3
Views: 422

Re: Trials Bike Transmission

Thank you both! Obvious once it's pointed out!
by Raleigh Steve
5 Dec 2010, 3:33pm
Forum: Bikes & Bits – Technical section
Topic: Changes to riding position
Replies: 23
Views: 1292

Re: Changes to riding position

horizon wrote: (BTW on modern bikes the tendency is for a lower level for the bars on anything bar a hybrid.)


I don't agree with that. In the 90s all racing bikes were just that. Now there are loads of bikes that look like racing bikes (Specialized Allez, Roubaix etc etc) that have an extended headtube and sloping down tube that makes the handlebars much higher than would normally have been the case 10 or 15 years ago.
by Raleigh Steve
29 Nov 2010, 10:07pm
Forum: Bikes & Bits – Technical section
Topic: Trials Bike Transmission
Replies: 3
Views: 422

Trials Bike Transmission

Not sure if this is the right place to ask this question, but I'm becoming a bit of an armchair trials rider, after watching Danny Macaskill videos!

I wondered if anyone knew how the transmission on the bikes works - they seem to have a freewheel they also have drive when they pedal backwards. See 1:44 into this video for an example:

http://www.bikeradar.com/news/article/v ... ndon-28544
by Raleigh Steve
29 Nov 2010, 9:48pm
Forum: Bikes & Bits – Technical section
Topic: Acera Front Derailleur - capacity
Replies: 3
Views: 403

Re: Acera Front Derailleur - capacity

Thanks - that's what I thought. I'll give it a go anyway!
by Raleigh Steve
29 Nov 2010, 9:32pm
Forum: Bikes & Bits – Technical section
Topic: Acera Front Derailleur - capacity
Replies: 3
Views: 403

Acera Front Derailleur - capacity

Hi

I am replacing the chainset on my mountain bike from an FSA to a Deore (only 50 quid inc BB on Chain Reaction) but the biggest ring is 44T whereas it was 42T on the FSA. Shimano Tech Docs say the maximum an Acera derailleur can cope with is a 20T gap between biggest and smallest rings. Do you think it will be ok with 44T outer ring instead - i.e. a 22T gap?

Thanks

Steve
by Raleigh Steve
21 Nov 2010, 12:27pm
Forum: Bikes & Bits – Technical section
Topic: Front Derailleur Adjustment Problem
Replies: 11
Views: 913

Re: Front Derailleur Adjustment Problem

Have you removed the crank recently? I had a similar problem recently and it turned out that I had undertightened the crank.
by Raleigh Steve
11 Nov 2010, 8:12pm
Forum: Bikes & Bits – Technical section
Topic: Matching a crankset to bottom bracket
Replies: 4
Views: 607

Re: Matching a crankset to bottom bracket

I had to check recently and I'm pretty sure Truvativ cranks use a 113mm, but don't know which taper and given the choice I'd be going for Campag!
by Raleigh Steve
23 Oct 2010, 9:31pm
Forum: Bikes & Bits – Technical section
Topic: what age dawes super g
Replies: 8
Views: 1088

Re: what age dawes super g

I really like restoring old bikes and if yours fell into my hands by the same means I would probably restore it. But it won't be cheap I don't think - it's very easy to spend a few hundred pounds by the time you've bought at least one new wheel, tubes, tyres, saddle, cables, chain, freewheel, mudguards, bar tape and dealt with a few unexpected issues (might it need a new headset or bottom bracket? New chainwheels?). As I said, I would probably be tempted to carry on becuase it is fun (I've done it with a Raleigh Twenty which is much less worthy of restoration) but probably you could buy just as good or a better bike for your son with the money you will need to spend to get it going, but it will be probably be a less loveable bike.
by Raleigh Steve
22 Oct 2010, 10:08pm
Forum: Bikes & Bits – Technical section
Topic: Seat packs and rack bags
Replies: 11
Views: 1501

Re: Seat packs and rack bags

I've not really had those problems. You need to make sure it is well tightened or it came come loose, but it's never been a problem for me once I have done this (the first time I used it it came loose, but I really hadn't tightened it much).

I think it has been redesigned because it wasn't available for a while.

In terms of QR, I definitely wouldn't want to be taking the bag off very often - it'svery easy to release but not very easy to put back on - basically the design is that a couple of rods slide through the loops of the leather straps, which are pretty narrow. But it's only a 30 second job, just a bit fiddly.
by Raleigh Steve
22 Oct 2010, 10:03pm
Forum: Bikes & Bits – Technical section
Topic: A question about washers (it's as boring as it sounds)
Replies: 18
Views: 4429

Re: A question about washers (it's as boring as it sounds)

Could go either way! Depends whether you mount the ring outside or inside the crank. In my case it is inside but I want to move it further in, so need a spacer.
by Raleigh Steve
22 Oct 2010, 7:08pm
Forum: Bikes & Bits – Technical section
Topic: A question about washers (it's as boring as it sounds)
Replies: 18
Views: 4429

Re: A question about washers (it's as boring as it sounds)

well i guess it could be either, but for me it is the wrong way!
by Raleigh Steve
22 Oct 2010, 6:59pm
Forum: Bikes & Bits – Technical section
Topic: A question about washers (it's as boring as it sounds)
Replies: 18
Views: 4429

Re: A question about washers (it's as boring as it sounds)

Yes maybe it doesn't matter.

There were some M10 ones in the shop that looked like they had a small enough outer diameter. I was just surprised to think that a chainring spacer was a specially manufactured part and not some sort of standard washer. But I guess it would explain the price.
by Raleigh Steve
22 Oct 2010, 6:51pm
Forum: Bikes & Bits – Technical section
Topic: A question about washers (it's as boring as it sounds)
Replies: 18
Views: 4429

Re: A question about washers (it's as boring as it sounds)

I thought about that but it is too thick - a chainring is 3mm thick I think and I would like about 1.5mm.

But as much as anything else, now that I have delved into the world of washer sizes I wondered if anyone knew whether there was a washer available that fell between a M8 and an M10 or are people actually manufacturing chainring spacers that have no other washerly function?!
by Raleigh Steve
22 Oct 2010, 6:14pm
Forum: Bikes & Bits – Technical section
Topic: Seat packs and rack bags
Replies: 11
Views: 1501

Re: Seat packs and rack bags

I would highly recommend a saddlebag, as no doubt will countless others. You can fit it to any saddle with a Bagman QR, and this is useful for support in any event where it won't be resting on a mudguard or rack:

http://www.sjscycles.co.uk/carradice-ba ... prod11247/

A beam rack seems like a lot of extra weight, for not much carrying capacity, whereas the unladen Bagman is very light.

Not sure about bolting a beam rack to a carbon seat post, but I use the Bagman and saddlebag on a carbon racing bike from time to time and have no problems - the only attachment is to the saddle rails.