Frame Weights

For discussions about bikes and equipment.
SRV
Posts: 27
Joined: 3 Jul 2019, 2:21pm

Frame Weights

Postby SRV » 5 Oct 2020, 12:01pm

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
Posts: 42316
Joined: 4 Jan 2012, 6:25pm

Re: Frame Weights

Postby Brucey » 5 Oct 2020, 12:24pm

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
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

SRV
Posts: 27
Joined: 3 Jul 2019, 2:21pm

Re: Frame Weights

Postby SRV » 5 Oct 2020, 2:01pm

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
Posts: 1551
Joined: 9 Jun 2008, 8:06pm

Re: Frame Weights

Postby rogerzilla » 5 Oct 2020, 8:58pm

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
Posts: 2794
Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: Frame Weights

Postby peetee » 5 Oct 2020, 10:33pm

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’.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

User avatar
Mick F
Spambuster
Posts: 50716
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Frame Weights

Postby Mick F » 6 Oct 2020, 8:44am

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.
Mick F. Cornwall

greyingbeard
Posts: 851
Joined: 24 Mar 2015, 10:41pm

Re: Frame Weights

Postby greyingbeard » 6 Oct 2020, 11:16am

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
Posts: 1551
Joined: 9 Jun 2008, 8:06pm

Re: Frame Weights

Postby rogerzilla » 6 Oct 2020, 12:08pm

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
Posts: 1689
Joined: 2 Jan 2017, 5:56pm

Re: Frame Weights

Postby Jamesh » 6 Oct 2020, 12:17pm

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
Posts: 126
Joined: 1 Apr 2015, 9:58am
Location: Caerphilly

Re: Frame Weights

Postby GranvilleThomas » 6 Oct 2020, 12:52pm

SRV wrote: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
Posts: 875
Joined: 10 Jan 2008, 8:44pm
Location: Highland Heights Kentucky,, USA

Re: Frame Weights

Postby scottg » 6 Oct 2020, 1:40pm

greyingbeard wrote: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.

tubes.jpg
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Deutsche Luftschiffahrts-AG
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