SB8945 SBDU Nottingham 753R 58cm Frame Weight

TI-Reynolds Frame Weight – It’s Not an Exact Science

The search terms used by people who reach my blog are often connected to searching for information about the weight of a frame, specifically Reynolds 753 and Reynolds 531. So I thought I would write a little post to show the weight information I’ve collected on my own frames. I have frame weight data on several SBDU frames across a range of Reynolds tube sets. What I’ve found is that it isn’t simply a case of saying that every 57cm Reynolds 531 frame will weigh the same. Lots of factors influence frame weight.

Frame weight is a product of the materials, geometry and components chosen to build the frame. Frames that have the same size seat tube and that share the same Reynolds frame transfer won’t necessarily work out at the same weight, they will be in the same range, but not exactly the same.

Materials

One type of Reynolds tube is the same as the other, right? Reynolds 753 is Reynolds 753 and 531 is 531 right?

No, like all Reynolds tube sets, Reynolds 753 came in at least 3 and probably 4 different tube gauges. A 753 double butted top tube with a profile of 0.7/0.5/0.7 will be heavier than the same 753 top tube with a 0.7/0.3/0.7 profile. The latter has less steel, it will weigh less. It may not be significant, but put all these little differences together and you have a different weight frame.

Geometry

How can geometry affect frame weight?

Steel has a weight, the more you use the more weight, the less you use, the less weight. Two front triangles for a given seat tube length can have different geometry; different top tube length and different angles can also mean different head tube length and different down tube length. A tighter rear triangle uses shorter chain stays. More clearance on forks will mean either longer fork blades or a deeper fork crown which both add weight. Again, not significant differences in isolation, but when all these individual differences are put together, they begin to add up.

This is the geometry of my 753 Time Trial Special; this frame is made from Metric tubed Reynolds 753 and is a 56cm frame measured centre to top (c-t).

Raleigh SBDU Ilkeston Time Trial Special Dimension Measurements H Reference
Raleigh SBDU Ilkeston Time Trial Special Dimension Measurements H Reference

It weighs 1629 and 644 grams for frame and forks respectively.

Raleigh SBDU Ilkeston Time Trial Special 753 1978 SB2692 H591 Weights
Raleigh SBDU Ilkeston Time Trial Special 753 1978 SB2692 H591 Weights

Any other 56cm Reynolds 753 Metric tubed frame will probably come out at a different weight.

Lugs and Frame Fittings

Plain lugs or lugs with cut outs? The more material you remove from a lug, the less it weighs. Different BB shells, different seat lugs. Short dropouts or long dropouts, dropouts that are drilled or that have mudguard eyes. Seat stay cap finishing, thin plate caps or something more fancy… every item used on a frame to connect the tubes together, combined with the chosen geometry and gauge of tube will produce a different final frame weight.

My TI-Raleigh Specialist Bicycle Development Unit SBDU Ilkeston Frame Details
My TI-Raleigh Specialist Bicycle Development Unit SBDU Ilkeston Frame Details

My Data

Whenever I’m asked, I always quote frame weight in grams, and in a weight range, associated with a size. So a 56 – 57cm early Metric 753 frame will range from 1620 – 1700 grams according to my data. This is enough to cover all the variables you might encounter with geometry and fittings.

I have two almost identical SBDU TI-Raleigh Team Pro 753 Metric frames in 57cm. The have different BB shells, different lugs and different fork crowns but are identical in every other respect.

1980 Metric 753 57cm Team Pro Drilled Portacatena Ends RGF BB & Vagner Crown 1645/639 grams
1982 Metric 753 57cm Team Pro Drilled Portacatena Ends Cinelli BB & SC Crown 1687/643 grams 
 
So there isn't a massive difference in weight between them but the changes in frame
fittings does affect total weight.

I think the reason for searching for a frame weight is to try and establish the type of tubing a frame is built from. Reynolds 753 and 531 Double Butted/531c do have a significant difference in weight between them in the standard gauge versions.

Standard gauge 753 for a 57cm   : 1645 grams
Standard gauge 531c for a 57cm  : 1910 grams
Standard gauge 531DB for a 57cm : 2050 grams

For standard gauge tubes, and for frames with similar fittings and geometry, 
you can see, and often feel a difference in weight.

Frame weight cannot tell you everything. The important thing to remember is the hidden variable which is tube gauge. I have the perfect example of this problem. I have 3 Time Trial Special frames, all with a 56cm seat tube. There have some slightly different frame features but are all in original paint with original Reynolds frame transfers, so luckily, I know exactly what each frame is built from.

Reynolds 753   Metric 56cm Time Trial  : 1629 grams
Reynolds 531SL Metric 56 cm Time Trial : 1651 grams
Reynolds 531c  Metric 56 cm Time Trial : 1698 grams

If these frames did not have the original Reynolds frame transfers 
it would be very difficult to identify these frames based on weight alone.

This is the data I’ve collected on my SBDU frames.

My TI-Raleigh SBDU Frame Weight Data
My TI-Raleigh SBDU Frame Weight Data

Frame weight can, if used in context, help to narrow down a question about frame tubing but as this blog post title said, it is not an exact science.

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Written by Neil McGowran

Blogger of all things to do with the Specialist Bicycle Development Unit (SBDU) and TI-Raleigh Ilkeston.

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