GT Grade Carbon 105 – Help with Fit

I’m 5’10” and went for the

I’m 5’10” and went for the 55cm. I have long body, short leg and after reading they came up big was worried I’d gone for the wrong size. However it’s absolutely spot on, plenty of seat post showing, and a slammed 120mm stem. Perfect. 

b8nducci wrote:

Hoffmonkey wrote:

6ft and I ride a 55. I still feel quite stretched out. I’ve heard from various sources that the GT Grade runs big so most people tend to go a bit lower than they otherwise would.

Also, the smaller the frame, the less of the triple triangle effect there is on the frame – aesthetically, I think the smaller bikes look prettier around the seat stays and seat post area!!

 

Good luck, I’m more than happy with my 55 – done 1700 miles on it on tow paths and on road and it’s been great. 

 

HI, I was looking into the Grade and am worried about it being to big at 56cm. I am 6 ft with a 32.5 in inseam and 25 inch arms. Do you think I should look into a 55cm? thanks for ur help

I have longer legs than you. My 56 cm Grade has a 160mm head tube, the new one 162mm. I reckon the 55cm size would suit you but either would probably be OK.

This is the sizing guide on Wiggle:

                        51cm              53cm                 55cm               56cm           58cm                   60cm
Height cm 158 – 168cm 168 – 175cm 175 – 183cm 183 – 191cm 191 – 196cm 195 – 200cm
ft                   5′ 2″ – 5′ 6″        5′ 6″ – 5′ 9″      5′ 9″ – 6′ 0″    6′ 0″ – 6′ 3″   6′ 3″ – 6′ 5″     6′ 5″ – 6′ 7″
Inside Leg cm 72 – 78cm  77cm- 82.5cm 81.5 – 87cm 86 – 89.5cm 89.5 – 93cm  92 – 96cm
inches                 28″ – 31″   30″ – 32″               32″ – 34″        34″ – 35″       35″ – 37″        36″ – 38″

                                                               51cm 53cm        55cm        56cm       58cm        60cm
Seat Tube – Center to Top mm 495mm 535mm 550mm 560mm 605mm 635mm
Top Tube (Virtual) mm                515mm 535mm 550mm 565mm 580mm 600mm
Stack mm                                          624mm 772mm 786mm 800mm 829mm 843mm
Reach mm                                         428mm 433mm 447mm 456mm 458mm 474mm
Standover Height mm                  742mm 772mm 786mm 800mm 829mm 843mm
Head Tube Angle Degrees           69° 70° 70.5° 71.5° 72° 72°
Seat Tube Angle Degrees             74.5° 73.5° 73° 73° 72.5° 72°
Chainstay Length mm                   430mm 430mm 430mm 430mm 430mm 430mm
Head Tube mm                                 121mm 142mm 162mm 182mm 207mm 231mm
Bottom Bracket Height mm        280mm 280mm 280mm 280mm 280mm 280mm
Fork Rake mm                                   45mm 45mm 45mm 45mm 45mm 45mm
Wheelbase mm 1017mm 1019mm 1025mm 1031mm 1035mm 1049mm
Bottom Bracket Drop mm 70mm 70mm 70mm 70mm 70mm 70mm
Front Centre mm 597mm 599mm 605mm 610mm 615mm 628mm

Hoffmonkey wrote:

6ft and I ride a 55. I still feel quite stretched out. I’ve heard from various sources that the GT Grade runs big so most people tend to go a bit lower than they otherwise would.

Also, the smaller the frame, the less of the triple triangle effect there is on the frame – aesthetically, I think the smaller bikes look prettier around the seat stays and seat post area!!

 

Good luck, I’m more than happy with my 55 – done 1700 miles on it on tow paths and on road and it’s been great. 

HI, I was looking into the Grade and am worried about it being to big at 56cm. I am 6 ft with a 32.5 in inseam and 25 inch arms. Do you think I should look into a 55cm? thanks for ur help

I’m the same height as you

I’m the same height as you but with shorter legs and my 53 (‘small’ in the UK) 2016 Grade 105 Carbon feels like a perfect fit. These bikes are big, this size is a medium at least by any other manufacturer so don’t be put off by ‘going small’ because really you aren’t.

For me, even a small had a bit too much reach and I replaced the stock GT stem (which I think is +-7 100mm, though GT don’t specify) with a Zipp Service Course +-6 90mm and it felt bang on. At the same time I replaced the bars with Zipp Service Course 80 in 44cm as I wasn’t too keen on the flare of the GT ones and wanted a bit more width on the flat part of the bar.

Also, if you go for the larger size, you won’t have very much seatpost exposed. For stock issue it’s a very good seatpost and you won’t be taking advantage of this if there’s not much sticking out above your frame flexing and absorbing buzz as it should.

Generally the level of finishing kit on the Grade is outstanding by comparison to others you might be looking at. This really swayed me especially as, like you, I got a good deal. The Stan’s Grail are a perfect mix of toughness and versatility and I would strongly recommend going tubeless as these wheels make it so easy, they were actually designed for the Grade. I’d say I haven’t had a puncture since going tubeless but that’s not true. It would be more accurate to say I haven’t had to fix a puncture since going tubeless. When you find in the morning your tyre is flat, you pump it up and go for a ride and it’s fixed! Genius. I used thin rim tape just in the channel, covering the spokes, and fitted Scwalbe S-One (now G-One Speed) with no problems.

Back to the fitting, I’d take the advice of the professionals in your bike shop.  They’ve seen you on it and they know when a bike is the right size for someone. It sounds like they’ve got it right to me and as others have said, you can fit a bike out to be bigger but you can’t make one smaller.

Your height is only part of

Your height is only part of the puzzle, fit depends massively on things like core strength, arm length, flexibility and even as simple as your ‘effective torso’ length.  Personally I think inseam is almost irrelevant.

A small frame can be fitted bigger but a larger one not fitted smaller (beyond short or a increased angle stem – like a 17 degree).  Limitations in sizing up a smaller frame are obviously bar drop as you experienced, but also toe overlap with front wheel, seat post (can buy a longer one within reason), and handling slows as stem length increases (also note that stem length and fork geometry work together, so some bikes more sensitive than others to length change and some suit a longer or shorter stem by design).

Moving saddle forward will put more weight on hands and neck, it is not a good way to make a bike that’s too long fit.

If the 55 is too big and cannot be made entirely comfortable without a stem shorter than 90mm or so then leave it.  If the 53 is too low and can’t be made entirely comfortable with spacers and a flipped stem the leave it.

If neither works perhaps a taller more endurance frame would suit, and this is not the bike for you.

I think fit is very important

I think fit is absolutely crucial but it is tied to function. If you want an easier commuter and better off-road bike I’d think about the 55 and maybe shortening the stem. If what you want is mainly a road bike, however, I’d go with the 53 and perhaps a longer stem with a bit of rise.  You might eventually even end up lowering the bike a few spacers as you get used to the position. 

Inseam is the least meaningful measurement. If anything I’d advocate the longer seat post for a little extra flex. Too little tube sticking out makes for a harsher ride, IMHO.

P.S. I’m 6’1″. I ride a 56cm road bike and a 19.5″ MTB.

Sorry, probably going to put

Sorry, probably going to put a spanner in the works but for what it is worth – I am about the same height as you, 20 years older and I have ridden thousands of miles on my 55cm 2015 carbon grade on and off-road with no problems.  

For the amount of aggro
For the amount of aggro getting the bar height right and you looking like you’re riding a childs frame plus even with the stem flipped (or god forbid an ugly 20degree upangled) there might notbe enough steerer length to achieve an ideal/comfy position. Get the bigger size and just buy a stem 20mm shorter.
Some stating this will hqve an adverse affect on handling…okay whatever, I guess when you see 130/140/150/160 stens on bikes for frames that are way too small that doesn’t have an effect either and these are often pros.