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Discussion Starter · #1 ·
Hi

I had a professional fit done yesterday (Dartfish) and found out that I am missing 5cms of handlebar height on my Giant X4.

The fitter replaced my stem and was able to reduce the needed height by 1cm.

I order to get the remaining 4 cms, I thought of replacing the 100cm fork for a 140cm version.

I don't see why my riding style should change much, i'll probably adjust my front suspension a bit more stiffer to compensate for the travl.

Can anyone think of any reason I could not do this?
 

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Discussion Starter · #3 ·
mtnbiker72 said:
Because it will totally fuk up your geometry and might void your warranty.

Maybe a higher rise bar, much cheaper
I already have a riser bar. :(

The geometry is okay, the professional bike fitter adjusted me on his fitting bike with the missing 5 cms.

The warranty i'm not too concerned as the LBS said they would cover me.
 

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Huh? 5cm too low? That can't be right! Are you sure the fitter isn't pulling your chain? Are you 7ft tall?

Your bike is designed for a 100mm fork, I suggest that. I have used a 140mm because that's all I had at the time, on a XC bike, doesn't have that much effect negatively on climbing surprisingly, it is supposed to be potentially dangerous.

If you're desperate for more height it might be possible to send you fork back to the manufacturer and get a longer steerer tube attached and then run more spacers.
 

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Discussion Starter · #6 ·
lew242 said:
Huh? 5cm too low? That can't be right! Are you sure the fitter isn't pulling your chain? Are you 7ft tall?

Your bike is designed for a 100mm fork, I suggest that. I have used a 140mm because that's all I had at the time, on a XC bike, doesn't have that much effect negatively on climbing surprisingly, it is supposed to be potentially dangerous.

If you're desperate for more height it might be possible to send you fork back to the manufacturer and get a longer steerer tube attached and then run more spacers.
lol no, not that tall. My legs are disproportionately longer than my torso.

do you know how it's supposed to be dangerous? i'm thinking of less precise handling, but can't think of any other reason.

yes, i thought of the steerertube lengthening as well. Not sure it would help in the handling dept. as it would take me farther away from the headtube.

EDIT: I'm 6'1.
 

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Just one, but enough to maybe stop you considering doing this......Frame was designed around a 100mm fork and the stresses that would put on the headtube and headtube/seattube/toptube junction and more than likely is built a bit stronger than eeded to handle those forces. Now you want to add a fork that is 40% taller than you previous fork, which will add a lot more stress in that area than was designed for, so what could happen - catostrophic failure and the headtube snaps off and you get (if you're lucky) a very nasty face plant into the ground, if you're not that lucky very seriously injured, maybe even killed when impalled by the broken tubes or some such else around the trail.

My suggestion to you is to look for another frame that has a longer HT and use a rise stem and bars to get the height right. BTW what size is your current bike? I'm thinking way small for you if you need that much adjustment, even with long legs - I can easily fit a L frame and I have a 35.25" inseam and am 6'2.25" tall.

xfimpg said:
lol no, not that tall. My legs are disproportionately longer than my torso.

do you know how it's supposed to be dangerous? i'm thinking of less precise handling, but can't think of any other reason.

yes, i thought of the steerertube lengthening as well. Not sure it would help in the handling dept. as it would take me farther away from the headtube.

EDIT: I'm 6'1.
 

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Discussion Starter · #8 ·
LyNx said:
Just one, but enough to maybe stop you considering doing this......Frame was designed around a 100mm fork and the stresses that would put on the headtube and headtube/seattube/toptube junction and more than likely is built a bit stronger than eeded to handle those forces. Now you want to add a fork that is 40% taller than you previous fork, which will add a lot more stress in that area than was designed for, so what could happen - catostrophic failure and the headtube snaps off and you get (if you're lucky) a very nasty face plant into the ground, if you're not that lucky very seriously injured, maybe even killed when impalled by the broken tubes or some such else around the trail.

My suggestion to you is to look for another frame that has a longer HT and use a rise stem and bars to get the height right. BTW what size is your current bike? I'm thinking way small for you if you need that much adjustment, even with long legs - I can easily fit a L frame and I have a 35.25" inseam and am 6'2.25" tall.
That certainly isnt a picture i want to see of myself or anyone!

My current ride is a Giant Anthem X4 in a Large. I'm 6'1.

Here are my exact measurements:
Inseam: 86.4 cm / 33 in
Saddle Height - BB to top center of saddle: 799 mm / 314.6 in
Saddle Setback - BB horizontal to tip of saddle: -75 mm / -29.5 in
Saddle Angle - Angle of saddle to horizon: 1 deg
Effective Seat Tube Angle - BB to center of saddle:75 deg
Bar Rise - Top of bar vertical to top center of grip: 28 mm / 11 In
Handlebar Reach - Tip of saddle to stem center: 547 mm / 215.4 in
Saddle to Bar Drop - Center of saddle to bar top: -32 mm / -12.6 in
Grip Reach - Tip of saddle to center of grip: 495 mm / 194.9 in
Grip Drop - Top center of saddle to top center of grip - denotes grip lower: -4 mm / -1.6 in
Handlebar Width End to End: 646 mm / 254.3 in
Handlebar Stack: 723 mm / 284.6 in
Handlebar Reach - BB to center of bar: 472 mm / 185.8 in
 

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Was being a bit dramatic there with my response, sort of. It is a very realistic possibility if the bike was only given a very narrow margin of tolerance compared to what was needed. Saying that I had an '05 Trance, which was originally designed around 100mm travel/fork and people safely used up to a 140mm fork on it, just didn't want you to go in there thinking only thing that could happen would be bad handling. Best bet is to contact Giant and ask them directly if they would warranty the frame with that fork, if they say yes, then I'd feel very confident on doing so since they wouldn't open themselves up to that sort of liability if it wasn't safe.

Check those measurements, I think the decimal point has been overed one - taking it the M measurements are the accurate ones and the inches were converted ;) Using this fact I can't see why you'd be having such an issue with the bar height - truly a lot of your measurements don't make sense to me.

For me my key measurements are .....
1) back of saddle to front of bars (saddles come in all different lengths, so measuring from the front tells me nothing if the saddles aren't all the same length)
2) centre of BB to top of saddle
3) back of saddle to centre of BB (horizontally)
4) from ground to top of grip (bike being held level/paralell to the ground)
5) from ground to top of saddle to then determin bar drop from saddle.
6) stem length and rise
7) bar width and sweep/upsweep

Best thing you could do is post a pic of yourself on the bike in the current setup. It seems strange that you're having this trouble to get it to fit right, especially with a 33" inseam, that's nothing leggy for a 6'1" person. Is this a new bike? If so you might want to consider looking at the AnthemX 29er version instead, with the bigger wheel the bars might come up closer to what you want.

BTW this "fit" is it what you feel comfortable on or just what an "expert" told you you should be comfortable on?


xfimpg said:
That certainly isnt a picture i want to see of myself or anyone!

My current ride is a Giant Anthem X4 in a Large. I'm 6'1.

Here are my exact measurements:
Inseam: 86.4 cm / 33 in
Saddle Height - BB to top center of saddle: 799 mm / 314.6 in
Saddle Setback - BB horizontal to tip of saddle: -75 mm / -29.5 in
Saddle Angle - Angle of saddle to horizon: 1 deg
Effective Seat Tube Angle - BB to center of saddle:75 deg
Bar Rise - Top of bar vertical to top center of grip: 28 mm / 11 In
Handlebar Reach - Tip of saddle to stem center: 547 mm / 215.4 in
Saddle to Bar Drop - Center of saddle to bar top: -32 mm / -12.6 in
Grip Reach - Tip of saddle to center of grip: 495 mm / 194.9 in
Grip Drop - Top center of saddle to top center of grip - denotes grip lower: -4 mm / -1.6 in
Handlebar Width End to End: 646 mm / 254.3 in
Handlebar Stack: 723 mm / 284.6 in
Handlebar Reach - BB to center of bar: 472 mm / 185.8 in
 

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You must have replied while I was typing. From that response, here's my thoughts - find a new "pro" fitter. Unless you have serious back issues, you should not need to be that much higher over the saddle. For general XC your saddle should be anywhere from level to a couple inches below your saddle, all depends on what feels good to you and works for you when actually riding. I'm no spring chicken and have some back issues and my bars on all my bikes are below my saddle by at least .5".

xfimpg said:
I'm about 1 cm below the seat, so by the fitter's calculations i would need to be 2 cm above.
 

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Discussion Starter · #17 ·
LyNx said:
Was being a bit dramatic there with my response, sort of. It is a very realistic possibility if the bike was only given a very narrow margin of tolerance compared to what was needed. Saying that I had an '05 Trance, which was originally designed around 100mm travel/fork and people safely used up to a 140mm fork on it, just didn't want you to go in there thinking only thing that could happen would be bad handling. Best bet is to contact Giant and ask them directly if they would warranty the frame with that fork, if they say yes, then I'd feel very confident on doing so since they wouldn't open themselves up to that sort of liability if it wasn't safe.

Check those measurements, I think the decimal point has been overed one - taking it the M measurements are the accurate ones and the inches were converted ;) Using this fact I can't see why you'd be having such an issue with the bar height - truly a lot of your measurements don't make sense to me.

For me my key measurements are .....
1) back of saddle to front of bars (saddles come in all different lengths, so measuring from the front tells me nothing if the saddles aren't all the same length)
2) centre of BB to top of saddle
3) back of saddle to centre of BB (horizontally)
4) from ground to top of grip (bike being held level/paralell to the ground)
5) from ground to top of saddle to then determin bar drop from saddle.
6) stem length and rise
7) bar width and sweep/upsweep

Best thing you could do is post a pic of yourself on the bike in the current setup. It seems strange that you're having this trouble to get it to fit right, especially with a 33" inseam, that's nothing leggy for a 6'1" person. Is this a new bike? If so you might want to consider looking at the AnthemX 29er version instead, with the bigger wheel the bars might come up closer to what you want.

BTW this "fit" is it what you feel comfortable on or just what an "expert" told you you should be comfortable on?
Thanks, i might just call Giant and ask.
Typo on my behalf, my inseam is 35".
I also have limited flexibility when bending forwards, to the point that it compromises my reach significantly.
I don't have any pics, but i'll see if I can get something up here.

Thanks everyone for all your feedback, lots to assimilate here!
 

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Putting a 140mm fork on the bike will make the steering "flop". I tried increasing the travel on my hardtail bike by 35mm once (65mm to 100mm) and it was a disaster. Even the 15mm difference I ended up with (65mm to 80mm) is a big difference in handling. It tends to make the wheel turn to one side or the other and get kind of stuck there because of leverage which is known as flop. Add poor handling to the huge increase in stress at the head tube which will likely try to remove the headtube of your bike and you have some good reasons not to change your fork like that. Follow the fit advice from others like different stems or higher rise bars or just deal with it. Sometimes bike fits can interfere with the way a bike is meant to handle, if your legs are in proper pedaling position then you have much more leeway with upper body positioning. There shouldn't be any set position that your body needs to be in for mountain biking, riding bikes on trails is much less static than a road bike and therefore your seated body position isn't as important as if you were riding a road bike. Long hours in the saddle in the same body position is more of a road bike fit issue.
 

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Discussion Starter · #19 ·
zebrahum said:
Putting a 140mm fork on the bike will make the steering "flop". I tried increasing the travel on my hardtail bike by 35mm once (65mm to 100mm) and it was a disaster. Even the 15mm difference I ended up with (65mm to 80mm) is a big difference in handling. It tends to make the wheel turn to one side or the other and get kind of stuck there because of leverage which is known as flop. Add poor handling to the huge increase in stress at the head tube which will likely try to remove the headtube of your bike and you have some good reasons not to change your fork like that. Follow the fit advice from others like different stems or higher rise bars or just deal with it. Sometimes bike fits can interfere with the way a bike is meant to handle, if your legs are in proper pedaling position then you have much more leeway with upper body positioning. There shouldn't be any set position that your body needs to be in for mountain biking, riding bikes on trails is much less static than a road bike and therefore your seated body position isn't as important as if you were riding a road bike. Long hours in the saddle in the same body position is more of a road bike fit issue.
Thanks for sharing your experiences, that really clarifies things here.
I've spoken to my LBS and they have my current bike geometry and my measurements and are going to try to find me a match, possibly in a 29er.
If they don't find one, then i'll look at the custom fit route.
Adding a higher angled stem and/or riser bar greater than what I already have just doesnt make me comfortable.

Many, many thanks again folks for all your inputs, it has greatly helped!
I'll let you know how it works out!
 

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Another thing that affect fit that many people don't think about is handle bar width. widening or shortening the bars will pull you closer and lower as your arms move farther out. May not give you enough for what you need but a little here, little there, might get you where you need to be.

3cm isn't that much, that's alittle more than an inch. I would think with changing the bars, higher rise, maybe shorten them alittle, higher rise stem with a shorter base so you can put more spacers under it on the stem and you might be able to get an inch over your current setup.
 
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