Cycling UK Forum

I've now weighed the 23" bare frame & forks, they are 800g and 2031g (1lb 8oz & 4lb 8oz). The frame number is on the side of the seat lug & the rear spacing is actually 110mm, a wood block was pushing the stays out.

In the box of bits are some skinny Chater Leigh cranks & CL rat trap pedals, a reynolds alloy seat post, stem & bars, swiss made front & rear lights, dynamo & a pair of Weinmann 750 center pull brakes with levers (1970s?).

Does the frame weight point to 531? From the frame number position and head badge it does look like it's an Evans. Next bit is probably paint the frame, the battleship grey is a bit uninspiring but is it worth keeping to original?

How long is a piece of string! Without much research some rough and ready 'target' figures would perhaps be 8kg for race and 9kg to 11kg for the others. This heavily dependent on what you are prepared to spend and what you define as an Audax / adventure bike; mudguards, carrier, lights, tough tyres... (you mentioned pedals - these can vary by several 100g)

YMMV!

Roadster wrote:

Mr Evil wrote:

Tompsk wrote:Rotating mass IS double the effect of non-rotating...

Overall it's not though. Added mass requires more power for climbing, increases inertia, and increases rolling resistance. Moving that mass to the rim only affects inertia.

Only? Greater inertia requires higher energy expenditure to overcome it, and since there are two wheels on every bicycle, heavier rims/tyres are doubly unwelcome. Their increased flywheel effect is only of value when making steady progress over level ground, not so much when repeatedly climbing in hilly terrain or repeatedly accelerating during stop-start urban riding.

It is only slowing down and speeding up where rotating mass has the additional effect - and then only a minuscule 2% of the energy needed to accelerate the masses (see original post). Slowing down and speeding up in traffic, or otherwise, is dominated (98% of the energy) by the 'linear' acceleration of the masses. If you take wind resistance into account then the '2%' becomes an even smaller fraction of the total energy needed to go from 0 to 15mph.

Climbing hills is not effected by the effect of rotating masses (its only the total mass of the bike + rider + luggage which effects it).

Brucey wrote:one thing that is easy to overlook (not to mention difficult to gauge) is that the wheels are part of the 'unsprung mass' as it were; the front wheel especially, on the end of a springy fork (and arguably the whole bike at times) are flapping around on bumpy roads and this makes a difference; adding 10lbs to the wheels/bike is different to adding 10lbs around the rider's waistline!

So with light, springy bikes, they can ride well with relatively skinny hard tyres, whereas heavy/loaded bikes on the same tyres may be slower and can certainly feel awful on anything other than a perfectly smooth road. IME heavy bikes only ride OK on average roads if they are on relatively fat tyres.

So the widely-held belief that lighter wheels/bikes are 'faster' on the road may well be real rather than imaginary, but not for the reasons discussed thus far in this thread.

cheers

Virtually all the movement from the bike going over bumps is taken up by the tyres - I don't think the fork deflects up or down by anywhere near as much as the tyres (for a non-suspension fork). Could find out by standing on the pedals at 3 and 9 o'clock and bounce up and down with both feet and see how much the bottom bracket moves up and down. This is different to side to side springiness of the frame which can be seen and felt. The rider is a huge part of the mass so moving the body makes big differences - and is one of the skills you learn over the years to avoid potholes or ride through them if you can't get round them!

Mr Evil wrote:

Tompsk wrote:Rotating mass IS double the effect of non-rotating...

Overall it's not though. Added mass requires more power for climbing, increases inertia, and increases rolling resistance. Moving that mass to the rim only affects inertia.

Agree, only for accelleration does the mass have a doubling effect.

reohn2 wrote:It's my understanding that a wheel with heavier periphery will spin longer due to it's flywheel effect and so will accelerate slower but once up to cruising speed will be easier to keep moving,and when going slower such climbing the heavier wheel will take more energy to keep moving at the same speed as a lighter wheel.
The bigger the tyre and rim the heavier the wheel in relation to a narrow tyre and correspondingly narrow rim which is lighter.
How much that matters depends on speed,no?
So if I'm happy to climb slower than though cruise at a similar speed to a lightweight wheeled bike this should be OK,no?

If the speed does not change it does not take more energy to keep a rotating object going - however, having heavy anything makes it harder to go up hills! But if it is rotating or not makes no difference.

Brucey wrote:I recently attended a lecture given by the technical director of British Cycling. He and his colleagues did a sensitivity analysis of all the things you could vary in the bike and rider. Mass (even rotating mass) came out as relatively unimportant, even in track events; there were about half a dozen other things that could be varied with expectation of greater benefit.

What is true is that rotating mass is more important than other forms of mass; adding 100g to the rim and tyre is differt to adding 100g to the bike frame or rider.

cheers

Rotating mass IS double the effect of non-rotating - however it is 2x (not allot) = (not allot). e.g. my calculations show +100g on the outside of the wheel increases the energy needed to accelerate by 0.26%, 100g on a non-rotating part adds 0.13% to the energy needed. This is important if you are sprinting the final 250m of a grand tour or track event sprint when 10cm can mean winning or loosing - however probably slightly less important to most others?

"With the reference to shoes, would not the weight of one shoe balance out the weight of the other when talking about rotational mass.?
Yes the shoes weight will be additional to the whole so a light pair will be beneficial overall."

No - you would still have to speed up the pair. However, they are balanced - a bit like adding 2 lead weights on opposite sides of a wheel.

After reading many comments on rotating mass and what counts where I thought I'd do some sums (based on being an engineer and my A level maths studied many years ago). Having put the equations in a spreadsheet and making some reasonable(?) assumptions the results point to:

The effect of the rotating mass on a bike is less than 2% of the energy required to accelerate to a reasonable speed the masses involved (from 0mph up to 10 to 20mph).

The figures indicate the split is; 85% due to accelerating the riders mass, 13% accelerating the total mass of the bike and an additional 2% getting all the rotating bits up to speed. Note that this is independent of bearing friction and wind resistance which are not effected by the masses involved with all other things being equal.

Assumptions made: Rider 65kg, bike 10kg, 1/3 of 2kg wheels weight at the rim, weight of tyres (350g each) at rim + 25mm, shoes and pedals of 1kg total rotating at 60 rpm at radius of 170mm. I haven't calculated what the riders legs flapping up and down would add as I'm only looking at the rotating parts of the bike.

The equations are: linear energy = 1/2 m v^2, rotational energy = 1/2 m r w^2
(Where m is mass in kg, v is velocity in m/s, r is effective radius of rotating mass, w is angular velocity in radians per second)

The rotational energy one is interesting as it means having smaller wheels will not save rotational energy, e.g. with half diameter wheels the mass at the rim and radius are both halved but the angular velocity is doubled and being squared in the equation means it balances out. You will save on the 'linear' energy accelerating a smaller wheel of lower mass however.

My assumptions may be a bit off but they would have to be way off to change the 2% mentioned above by much unless my maths is wrong. Has anyone made calculations that differ much from the above? If you have some other assumptions I can quickly put them in the equation to see what effect that would have with my (slightly more than a) back of an envelope calculation

PS - I noticed I didn't take account of the tubes in the tyres (assumed 100g each) - this changes the percentage of the rotational energy to the total needed from 1.8% to 2.0%.

Thanks for the answers. I'll try to post some pictures this evening including some of the parts that were removed from the bike.

The forks have a number stamped on side of the tube above the crown - I'll see if there is one on the frame. One thing I noticed is the forks seem to be painted over chrome so the mid/dark grey with thin red lining round the lugs may not be original.

Are there any 50's Evans catalogues on line? I've found some 'late 30s' ones at the link below.

http://bulgier.net/pics/bike/catalogs/FWEvans-late30s/

My father gave me a bike in bits that he used to ride in the 50's and 60's. I can't seem to find much detail on the web but the parts look promising for a good club bike from that era. Any ideas on the frame?

Grey 23" frame with Chater Lea in raised letters under bottom bracket, missing head emblem - but paint marks show a single curly 'E' (shaped just like a mirrored number 3). Lugs are not too fancy but are shaped, with a small 'tang' on the front of the head tube. From the approximate weight and size of the tubes it doesn't look like gas pipe, I'm guessing (hoping?) 531. The frame has brazings which are not threaded but are square-ish and have an oval hole for guards and a rear rack. Wheel spacing seems to be 96mm front and 120mm rear.
Rear wheel with Dunlop light weight stainless steel rim and Sturmey Archer 4 speed hub, dated 1950.
No period front wheel (my dad said it had wing nuts and was stolen off the bike when he had locked it up.)

I've got a box of bits that were removed from the bike (including some interesting cantilever style brakes and hiduminium drop handle bars) but don't know how original or period (or safe to re-use!) those bits are.

I'm planning on getting it restored to original - just wondering how much effort to put in. If it is a fine example of the period then I'll try to restore to original as much as possible, if only a so-so bike I may just give it a quick powder coat, oil up the rear hub and put a few later bits on it, that are currently missing.

Ta for any replies.

Bigger wheels tend to have lower rolling resistance, especially over bumps.

However a Moulton or Brompton are generally not thought to be that much slower than their 'half' sized wheels would imply. I'm not sure how the relatively small difference between 26", 700c and 27" wheels would lead to 10% time difference. Perhaps tyre type or pressure is a factor.

ymmv!

Do you have a link to the SPA triple?

After visiting SPA there seems to be this one, with rings almost the same as I have (BUT they are easily changed (SPA CYCLES XD-2 Touring Triple Chainset):

http://www.spacycles.co.uk/products.php ... 0s109p2000

Or did you mean this one with rings a bit smaller than I was looking for? (SPA CYCLES 104 Touring Triple Chainset)

http://www.spacycles.co.uk/products.php ... 0s109p2657

Thanks for the replies so far.

The reason for going to MTB chainset is because the recent Shimano triple road sets are effectively fixed chainrings: The 130mm PCD middle is a converter ring with a (unique?) 92mm PCD mount for the inner. This means to change the ratios of these you would have to buy a different converter ring (to get 74mm PCD?) and another inner ring, but with the middle ring at 130mm PDC you are limited to 38t minimum. After that the outer ring needs changing too. So all 3 rings need to be changed to make any real changes.

So up Shimano creek without a pedal...

I notice in the Shimano MTB chainset installation guides they refer to 68 and 73mm bottom brackets and using 2.5mm spacers to set the offset. As a road triple has a chainline of 45mm and the Shimano MTB seem to have a chainline of 50mm can these 2.5mm spacers be used to change the offset? (assuming the inner chainring does not hit the chain stay...)

1) Do the chainsets come with spacers?
2) Is this a way to change the chain line?
3) Are there different MTB and 'road' Hollowtech II BB (Chainreaction say a BB is included with the chainset)

http://www.chainreactioncycles.com/shim ... -prod40496

TTFN

Another gearing question...

I have a 3x10 Tiagra groupset but want the gearing to be a little lower. I've found a "Shimano FC-M590 Deore 9-Speed 48/36/26T Triple Chainset" that will be way cheaper than changing the standard chainrings (50/39/30) on the Tiagra chainset and it fits the Hollowtech II bottom bracket - maybe...

Questions are:

1) Will the Tiagra and Deore chain line be the same if put on the Tiagra bottom bracket?
2) Is the Tiagra and Deore chainring spacing the same?
3) Will the Tiagra front changer cope with the 48/36/26 if I move it down the seat tube a few mm? (a 28T inner could be used if need be).
4) Will the '9 speed' chainrings work with a 10 speed chain? I know the official answer, but I've had 10 speed working perfectly on 30 year old chainrings.
5) Anything else I've not thought about?...

Many thanks for constructive answers.

PS - I like to tinker and I'm not ultra fussed what it looks like or if the gear changes are not up to TdF performance but would appreciate if there is anyone who knows of a show stopper on this possible set-up.