Bike fit thoughts? - Trek Emonda SL5 2021 (size 52 v 54)

[monkers]

What's the point in building bikes with compact geometry; i.e. sloping top tube frames, then having the seat tube sticking right up above the top tube junction so it has to be cut down to lower the saddle?. You might as well just have a larger conventional frame with a horizontal top tube! Some of the designers of these bikes must be on drugs.
It's not the carbon per se I object to, it's the totally impractical execution of the use of carbon fibre. I'm perfectly OK with a carbon frame if it has the same aesthetics, flexibility and adaptability as it's steel equivalent. They never do though. Still wouldn't ride on carbon forks mind you, no matter what.

We now have more choice. At one point in time, the bike was everyman's transport and workers passed the factory gates in their thousands; but the world is a different place now.

Carbon is a much more flexible material than steel in terms of adaptability to design parameters. Because it tends to be more expensive to produce, the cost to benefit ratio tends to mean that it will be bought by those seeking more performance - and in that sense it delivers. It can also be used in such a way to improve ride comfort; the best designs deliver in both of these areas.

Compact frame designs give the designer more opportunity for performance gains, granted that these days these gains are increasingly marginal.

Most of the world's new bike frames are already made from aluminium. Aluminium already had several advantages over steel for frame manufacture, but the newer manufacturing technologies such as hydroforming and the latest welding processes are enabling designers to make them closer to carbon in terms of performance and comfort. I might predict that we see a bit of a return to aluminium for race bikes as a result, but I don't see a return to barn gate frame design unless socio-politico-economic changes dictate that cars fall out of favour and the masses return to cycling.

I too have warm fuzzy memories of my earlier bikes with barn gate frame design, 531 tubing, pretty chrome lugs, Cinelli fork crowns etc, and I'd love another; but that's nostalgia and though I love the way they look I'll not fall into the trap of thinking those designs are faster or more comfortable.

One benefit of my Trek's semi-compact frame is that for a given saddle height I have increased stand over clearance. That may not mean much to you personally, but many riders will see that as a benefit, especially I suspect female riders who these days tend to reject flimsy steel step through designs in favour of a bike with more performance.

 

[Paul_Smith SRCC]

...I've been looking at the Trek Emonda SL5 2021 and been struggling with getting the right size, as it turns out I have really short legs compared to my upper body!

My dimensions:

• Height: 175 cm (5 ft 9 inches)
• Inseam (without shoes): 78 cm (30.7 inches).

My current bike dimensions: Triban RC500

• Stack: 56.9 cm
• Reach: 37.9 cm
• Saddle Rail Height: 63.0 cm
• Saddle Height: 68.0 cm

The sizing guides Trek list are very much a start point only, at 5ft 9" with your inseam at this stage I'd concur with what seems to be your conclusion which is to dismiss the 56cm Trek Émonda SL 5 Disc as a consideration. If physically you are not propionate it is not unusual that you may need to compromise; in your case do you focus on shorter inseam or longer torso when choosing the most appropriate size to accommodate your bike fit. This is where the store maybe able to help, yes the video riding around the car park in normal clothing and trainers is of value; but do they offer a fitting service to check everything more accurately in full cycle kit; shoes included? The fitter may also have a fitting jig like that shown below (supplied by Trek) which they can set up to both the 52 and 54cm which should help work out which of the two is the most suitable. Potentially both sizes may well be viable then availability will be a consideration, the store currently seem to have that 52cm but it's worth noting new orders for that model are currently 2023 in either size in both colours; hopefully those dates will improve but at the moment it is an odd time for bike stores.

There is of course more that influences the bike fit than height and inseam that they would take into consideration; such as flexibility, arm length, shoe size, ankling, range of motion and stability to name just a few. In your case you currently ride with a saddle height of 680mm, it is indeed a good idea to base a new bike on the current one, but only if it's correct of course. Hypothetically if at this moment we assume it is then for me 680mm would have the 52cm frame size higher up the list than the 54cm.

I understand your concern regarding the 52cm, it does seem like a small number for someone 5ft 9", but is it arguably not as small as the number alludes to; the effective top tube is 534mm. I have composed a BikeCAD drawing of the 52cm with your 680mm saddle height, using their 10mm set back seatpin, the latter could be upgraded to 20mm setback and with a 74.2 seat tube that may well be a viable option that a bike fit would help conclude. I have referenced the 20mm setback after reading that you are "not sure if what I'm feeling is cramped" compared to the medium Triban, interestingly the Trek has a longer reach by 4mm (379 Triban, 383mm Emonda) and 36mm lower (569Triban, 533mm Emonda) but I note the seat tube angle on the Triban is shallower at 73.5 degrees which is in part why the effective top tube is longer; I'd also wager that although it's not listed the Triban will have more than 10mm worth of seatpin set back.

I have also composed a Triban RC500 as close as I can for you, I only get so much data from each so some things I have to guess, especially with the Triban as they list less than Trek. Both quote frame 'stack' and 'reach' as well as well as frame angles and main tube lengths, so my guestimates should be close enough to be of value as in effect to an extent more often than not I am simply filling in the gaps. In this comparison I have used the same saddle height and setback to dial out the effect bike fit wise of the different seat tube angle and that I simply don't know seatpin set back of the Triban.

I have also morphed one into the other which may help visually illustrate the evolution each offers interms of bike fit; as you can see the Emonda has as to be expected a lower front end set up. Yes by design the Emonda is more aggressive but the drop to the bars is still conservative enough for the majority of riders on this style of bike.

If you enjoy some free technology you can compare both on the BikeCAD free version and make your own adjustments; if that appeals before you do anything create your free account so that you can save the drawing you have amended as 'your own' when finished. You can start with either their quick start drawing, or any from their design archive; including the two above that I have added for you.

Normally the free version works best if you do not display the chain and rear derailleur, plus even though technically you can I would not try and upload any brand logos as it is inclined to crash; as such I have added drawings of the Emonda and Triban for you without displaying those elements. I have a few tips on my own BikeCAD blog that may help, there is also quite a lot of useful Videos they publish on youtube

 

[Tapper3279]

The sizing guides Trek list are very much a start point only, at 5ft 9" with your inseam at this stage I'd concur with what seems to be your conclusion which is to dismiss the 56cm Trek Émonda SL 5 Disc as a consideration. If physically you are not propionate it is not unusual that you may need to compromise; in your case do you focus on shorter inseam or longer torso when choosing the most appropriate size to accommodate your bike fit. This is where the store maybe able to help, yes the video riding around the car park in normal clothing and trainers is of value; but do they offer a fitting service to check everything more accurately in full cycle kit; shoes included? The fitter may also have a fitting jig like that shown below (supplied by Trek) which they can set up to both the 52 and 54cm which should help work out which of the two is the most suitable. Potentially both sizes may well be viable then availability will be a consideration, the store currently seem to have that 52cm but it's worth noting new orders for that model are currently 2023 in either size in both colours; hopefully those dates will improve but at the moment it is an odd time for bike stores.
View attachment 598833
There is of course more that influences the bike fit than height and inseam that they would take into consideration; such as flexibility, arm length, shoe size, ankling, range of motion and stability to name just a few. In your case you currently ride with a saddle height of 680mm, it is indeed a good idea to base a new bike on the current one, but only if it's correct of course. Hypothetically if at this moment we assume it is then for me 680mm would have the 52cm frame size higher up the list than the 54cm.

I understand your concern regarding the 52cm, it does seem like a small number for someone 5ft 9", but is it arguably not as small as the number alludes to; the effective top tube is 534mm. I have composed a BikeCAD drawing of the 52cm with your 680mm saddle height, using their 10mm set back seatpin, the latter could be upgraded to 20mm setback and with a 74.2 seat tube that may well be a viable option that a bike fit would help conclude. I have referenced the 20mm setback after reading that you are "not sure if what I'm feeling is cramped" compared to the medium Triban, interestingly the Trek has a longer reach by 4mm (379 Triban, 383mm Emonda) and 36mm lower (569Triban, 533mm Emonda) but I note the seat tube angle on the Triban is shallower at 73.5 degrees which is in part why the effective top tube is longer; I'd also wager that although it's not listed the Triban will have more than 10mm worth of seatpin set back.
View attachment 598776
I have also composed a Triban RC500 as close as I can for you, I only get so much data from each so some things I have to guess, especially with the Triban as they list less than Trek. Both quote frame 'stack' and 'reach' as well as well as frame angles and main tube lengths, so my guestimates should be close enough to be of value as in effect to an extent more often than not I am simply filling in the gaps. In this comparison I have used the same saddle height and setback to dial out the effect bike fit wise of the different seat tube angle and that I simply don't know seatpin set back of the Triban.
View attachment 598798
I have also morphed one into the other which may help visually illustrate the evolution each offers interms of bike fit; as you can see the Emonda has as to be expected a lower front end set up. Yes by design the Emonda is more aggressive but the drop to the bars is still conservative enough for the majority of riders on this style of bike.
View attachment 598800

If you enjoy some free technology you can compare both on the BikeCAD free version and make your own adjustments; if that appeals before you do anything create your free account so that you can save the drawing you have amended as 'your own' when finished. You can start with either their quick start drawing, or any from their design archive; including the two above that I have added for you.

Normally the free version works best if you do not display the chain and rear derailleur, plus even though technically you can I would not try and upload any brand logos as it is inclined to crash; as such I have added drawings of the Emonda and Triban for you without displaying those elements. I have a few tips on my own BikeCAD blog that may help, there is also quite a lot of useful Videos they publish on youtube

Thanks for everyones help with this. Realise it was a bit late! I ended up going for the Emonda SL5 in size 54cm and it did end up fitting. Not sure why the first 54cm size didn't seem to fit me!