Frame Weights

[SRV]

This may be an old chestnut but I haven't come accross it, so here goes:
I have a Raleigh Record Sprint frame and forks (no headset or bb) which weigh 3.16 kg and a Gazelle Trim Trophy (ditto) which weigh 3.44 kg.
Now the RRS is a 25" frame and has a 501 main triangle and the GTT is a 24" frame and has a 531 main triangle.
How come the RRS is the lighter of the two?

[Brucey]

the main tubes are only a fraction of the weight of the whole frame, forks vary, and some tubesets were available as PG or DB. If the '531' tubes were not labelled DB, they'll be plain gauge.

Also in large framesets, some manufacturers would have specified thicker-walled tubing to make up for the loss of stiffness that otherwise occurs. The Gazelle might be like that and the Raleigh not.

cheers

[SRV]

Thanks. The RRS has been built up (with mostly non-original and cheap parts), the GTT has not.
The Raleigh weighs a shade over 25lb fully equipped (minus water) and despite this feels delightfully responsive and quite fast. I hope the Gazelle won't be a disappointment.
Mind you, the Raleigh is the lightest bike I've ever owned!
Now, if I were to lose a bit of weight..........

[rogerzilla]

The type of lugs, BB shell and dropouts can make a few ounces' difference, as can the stays.

My rule of thumb for a medium 22" frame is:

531DB 4lb 8oz
531PG 5lb 2oz

However, I have 531DB frames between 4lb 4oz and 4lb 10oz (I have a 531 Pro frame which is 4lb 2oz, but it has substantial lugs and thick stays for track sprinting).

(I don't include the fork in any of the above, as it's often made from different stuff).

[peetee]

It’s not unusual for a heavier frame to feel faster. 1/2 lb of extra steel in the right place can reduce flex and put more of your power into forward motion. This is especially true on larger frames.
Some, if not all, Trim Trophy frames were 531 main tubes only (seat, top and down tubes). That means that all four stays and the forks could be a more substantial gauge that found in the full 531 tube set.
The main tube decal reads ‘531 butted frame tubes’. The full tube set decal reads ‘531 butted tubes forks and stays’.

[Mick F]

My Mercian 531c wights, from some time back on here.
I kept the info for future reference.

I've just striped my bike down and now have a bare frame and forks.

I took the opportunity to weigh the frame and the forks. We've had questions on here before with folk trying to identify a frame to see if it's "exotic" of "gaspipe". Weight is a good indicator.

For the record:
My frame is 531c, 23.5", 73deg parallel.
Frame weighs 2170g
Forks weigh 692g
F+F is 2,862g

Notes:
The head tube still has the headset fixed cups in place, as do the forks.
Electronic kitchen scales may not be dead-on accurate, but the figures must be fairly reasonable.

[greyingbeard]

So how does a frame builder or designer decide which tubes to use ?

I suspect a lot of the manufacturers are led by fashion and label status, eg This model is 853 so its better etc. Theres probably a lot of engineering software for the big companies to design to an average rider weight, whatever that is.

What about the individual builders ? How do they decide ? Is it pot luck based on experience >? suggesting their early customers may not have got the ideal frame theyd hoped for ?

[rogerzilla]

There are whole books on that! Some builders will use a complete tubeset that you choose from a list, some will have a discussion with you about intended use and your size/weight, while others will just give you what they think is best in a "mix and match" approach.

[Jamesh]

I think for mass produced steel bikes economic decisions will make as much s difference as design considerations.

Bikes will be made for a average person as cheaply as possible whist still retaining the cache of Reynolds etc.

Custom bikes are what you spec is what you get...

Cheers James

[GranvilleThomas]

This may be an old chestnut but I haven't come accross it, so here goes:
I have a Raleigh Record Sprint frame and forks (no headset or bb) which weigh 3.16 kg and a Gazelle Trim Trophy (ditto) which weigh 3.44 kg.
Now the RRS is a 25" frame and has a 501 main triangle and the GTT is a 24" frame and has a 531 main triangle.
How come the RRS is the lighter of the two?

That's very interesting, and just proves that a lot of factors contribute towards the weight of a frame.

I don't know if you have seen this site below before, but It is about a guy who collects Raleigh frames and I found it a good read:

https://raleigh-sb4059.com/2016/09/17/t ... t-science/

[scottg]

So how does a frame builder or designer decide which tubes to use ?

You best designers know the following to be true.
From the ever useful RetroGrouch blogspot.