Help with sizing! - GT Grade

shuna

Hi all,

Newbie to this forum, nice to meet all of you!

I am currently looking for a road/gravel bike around the 1500 USD range and have pretty much settled on the GT Grade series.

I have also looked at Specialized, Merida, Cannondale, Marin, Felt, and others as well, but it just seems like GT fits my price range and has an overall good reputation.

Therefore, I am planning to purchase a GT Grade Carbon 105 (2017) or GT Grade Carbon Tiagra (2017).

However, I am still trying to decide on size. I have heard that GT runs a little bit large, so I am worried about the size I plan to purchase and need some advice.

I am 176cm tall with an inseam of 81.8cm, torso around 64.0cm, both arms around 67.0cm.
I went to a LBS to see if they had any GTs and it seems that there aren't that many shipped to Tokyo to begin with, so it will be very difficult to test ride a GT Grade.

I was able to sit on a size 56 Trek Crossrip 1 with a 90mm stem and it seemed comfortable. The LBS employee also said that my form didn't seem disfigured or anything, so a size 56 GT Grade should work for me in regards to top tube length and bar height.

However, after reading some GT Grade sizing threads on various forums, it seems that many people around the same height/inseam as me go with either 53 or 55, which has me worried that the 56 would be too large.

I understand that the GT Grade comes with a longer stem than most bikes (120mm for size 56).
I would prefer a more relaxed position rather than an aggressive one, which has me wondering if a size 56 with shorter stem would work better than a size 55 or lower since the stack/bar height will be higher.

So, it would be great if I could get advice on the below.

1. Would a stock size 56 GT Grade work for me or would the reach be too far? What if I swap out the 120mm stem for a 90mm stem? Or should I get a size 55??

2. Not really about sizing, but I can get a Carbon 105 for around 1650 USD or a Carbon Tiagra for around 1150 USD. Main difference between them from my understanding is that the 105 (obviously) has full Shimano 105 components, whereas the Tiagra has TRP HY/RD disc brakes, FSA Vero Chainset, and everything else Shimano Tiagra.
Is the Carbon 105 worth the additional 500 USD investment or would it be smarter to buy the Tiagra, play around with it, then eventually upgrade to 105 or above myself?
(Personal preference, but in terms of looks,I think I prefer the 105, the Tiagra is a bit bland in my opinion)


Apologies for the long post, any advice is greatly appreciated!

Thank you in advance.

doolie

Hi,

I ride a GT Grade 53 size and am slightly shorter than you at 173cm with an inseam of around 80cm. I found the 55 to be too long in the headtube. Very specific to me so don't take this as a sizing recommendation!

I'd normally look at a bike size of 54 for me if that in any way helps you.

D

shuna

Thanks for the advice!

I see, it does seem like 56 would be too large for me from various other posts I've seen, it's just that the numbers/geometry seems to say that 56 would be fine, which is the part that is confusing me.

The size 56 Crossrip 1 has a reach of 402 vs the size 56 GT Grade reach being 381...considering the fact that I didn't feel stretched on the Crossrip 1, I assume I won't feel stretched on the GT?

Also, I see a lot of good reviews for wiggle, but has anyone used TweeksCycles before?
Wiggle only has a size 56 GT Grade Carbon 105 (and size 55, 56 GT Grade Tiagra) but Tweeks seems to have a size 55 GT Grade Carbon 105, would like to know their reputation on this forum.

Thanks!

N0bodyOfTheGoat

I'm 178cm with 83cm cycling (not trouser) inseam, I've got short legs and a longer torso than average for my height.

My 58cm Cube has a reach of 388mm and stack of 610mm. Top of saddle to bottom bracket is ~73cm, it's no more than 2cm higher than the bar tops, not aerodynamic but good for my weak back by keeping me more upright.

The geometry for the GT Grade looks a bit odd to me, going on https://geometrygeeks.bike/bike/gt-grade-2017-1/ , I suspect you could go with 53/55/56 and maybe even 58cm depending upon how upright you want to be.

shuna

Thank you for the comment!

I see, so your Cube is around an size 60 for reach but closer to a size 56 for stack for GT geometry...this does make the GT (or Cube?) odd geometry.

I have read a lot of posts/replies to people that seem to have the same issue as me where they state to choose a 56 with shorter stem if they want a more relaxed position, and a 55 with stock stem if they want a more aggressive position.

I am also a little worried about the stand-over height; my inseam is 81.8cm and the stand-over height of the size 56 80.0. Do you think this is cutting it too close?

Captain Fagor

Be cautious of any sizing advice on the internet (including mine) but on the subject of reach, I'd go either the 53cm or the 55cm, not the 56cm. Better to get the right size frame than one that's too long and fit a stem that's too short.

FWIW, I bought a GT Grade Utegra 2016 and at 179/180cm with 83cm inseam opted for the 55cm frame (373mm reach, 578mm stack), which I run nearly slammed with a 120mm stem. I also ditched the flared bars which I didn't like, and replaced them with Deda Zero. One issue to factor into your considerations is that the hydraulic hoods have a longer reach than conventional rim brake hoods. They are ball-park 10mm longer. This alone means I am very glad I didn't get the 56cm frame as it would have been too long for me.

I hope you get something you are happy with.

shuna

Thank you for your input.

I was not aware of the longer-than-usual hydraulic hoods.
I guess they also contribute to the fact that many people have given their opinion that GT's run larger than conventional bikes.

Quick question, is a 90mm stem considered "too short"? I always thought that a 120mm was considered too long (or more geared towards racing) and that 90mm~100mm was more for a relaxed position (obviously depending on the geometry of the bike though).

I may be able to try out a size 53 Grade this week, will see if I can sit on it to check out the size.
Really wish I could test a size 55 and 56 too, but it doesn't seem like anything above size 55 GT reaches Tokyo =/

w00dster

90mm stem on an off-road style bike is fine. I run 80mm on my gravel bike, thats compared to 110mm on my race bike. For off-road i prefer to be slightly more upright and find for control purposes, especially on slower semi technical terrain I'm more in control of the bike with the shorter stem. Pretty much the same as MTB bars and stem.
This is completely different than just road riding though.
Be careful comparing the Trek Crossrip, these do come up small. I ride Trek bikes and the Crossrip in the same size feels more cramped than the other bikes. The Crossrip really is just Treks dropbar commuter that can also handle rougher stuff.

Bike sizing is very personal. Because of my riding style and lack of skill off-road i prefer a smaller bike. Just gives me more confidence that I'm in control. I bikepack off-road in fairly remote areas on my own so confidence in my set up is important.
If i was intending on mainly road riding and fairly gentle gravel i'd be less worried about stem length and more focused on the stack and reach.
Worth a read....
http://www.bikeradar.com/gear/article/y ... ant-50174/

shuna

I plan to take this probably around 70% on-road, 30% off-road and would prefer a little more upright position, so I assume a 90mm stem won't be a problem.

I see, so I was comparing a relatively smaller bike (Trek Crossrip) to a relatively bigger bike (GT Grade).
Do you know of any bikes that have similar sizing to GT?

Wouldn't stem length be a valid parameter here as it impacts how extended my body will be over the bike?
I did read that article on how top tube length is irrelevant and how I should focus on stack and reach.
If I look at the numbers though, the size 56 Crossrip (40.2 reach, 59.6 stack) I sat on has a similar reach and stack to the size 56 Grade (38.1 reach, 60.1 stack).

Albeit the Crossrip had a 90mm stem, if I also switch out the 120mm stem from the GT, it should have a shorter reach than the Crossrip.

If I just look at the numbers, the size 56 seems to fit, I'm just confused at why some people with similar same height/inseam/torso length than me (or larger) say they felt the size 56 or even size 55 GT was way too large...
I guess it as to do with personal form and positioning over the bike?

pssyche

I have size XL(58) aluminum 2015 model, but i suppose geometry is the same for newer models. I'm 1.87m with 88cm inseam, have slammed stem but changed stock 125mm for 110mm, ride a lot in the drops and almost exclusively on road.

shuna

Thank you for your input.

Still can't say for certain until I go to the LBS to test ride, but I'm beginning to think that size 55 will feel better, albeit I can probably make a size 56 work with a shorter stem (stand over height and stack might be an issue though...).

Wiggle only has a size 56 GT Carbon 105 while Tweeks seems to have a size 55.
However, Tweeks' shipping to Japan is around 230 USD compared to around 70 USD from Wiggle...

Also have heard/read many good reviews about Wiggle but many mixed reviews for Tweeks, anyone have a story to share?

ADSmith

Hi,

I'm the same height as you and bought a 55cm grade a few weeks ago. This size is borderline too big for me - I've not got much seat post showing and have had to fit a shorter stem. The saddle is also as far forward as it will go (this is how the shop set it up). There's no way I could ride a 56cm - I don't think I'd be able to stand over it apart from anything else. As it is now the bike is a good fit for me, but if I was buying it again I would want to try out a 53cm as well.

I got mine from Rutland Cycling and they still seem to have some 105 and Ultegra models left in the 55cm size https://www.rutlandcycling.com/bikes/ro ... ack_378757

Andy

shuna

Thank you for the info!

Definitely valuable information; pretty much convinces me that a 56 would be very far with the stock stem and still far with a 90mm.

I will likely go to my LBS to sit on a size 53 Grade Carbon Tiagra (since they don't have any other Grades).
Geometry should be the same as the 105 so I think that will give me a feel of the size.

However, considering the fact that if I buy the size 55 105, I would need to purchase from either Rutland or Tweeks, each don't seem to have as good a reputation as Wiggle and the shipping cost to Tokyo totals the bike to around 2000 USD, I may have to look for something else...maybe the size 55 Tiagra on Wiggle then upgrade to 105 by myself (although the fork is QR instead of thru-axle).

There seems to be a Specialized shop nearby as well so will try to check out a Diverge too!

shuna

Just an update after going to the LBS.

I did get a chance to get on a size 53 GT Carbon Tiagra.
Didn't have much of a problem, reach seemed a little bit short compared to other bikes I ridden.

Asked the LBS employee whether a size 55 would fit and he said that it likely wouldn't be a problem.
However, I would be in a more upright position, so if I have any intention on racing, he would suggest the 53.
He also mentioned that I could get a size 55 and shorten the stem/lower the seat to make it feel like a 53, but it is usually easier to make a smaller size feel like a larger size.

The only size 53 Grade Carbon 105 I could find was on CompetiveCycles, where the price of the bike is highest out of Wiggle and Tweeks, and the shipping to Japan is around 300 USD, effectively putting it out of range.

I did go by the Specialized shop but they didn't have the E5 Comp and no estimate of when they will have stock.
Diverge never really clicked for me anyways...

So I suppose now it's basically between size 55 Carbon Tiagra on Wiggle and size 55 Carbon 105 on Tweeks.
Difference in price is around 700 USD including shipping cost difference, will need to think over the weekend hard :?