xionchen4628

I am 5'8" and my inseam is 30". My LBS suggested that I use a 20" 2015 Trek 7.2 FX based on visual assessment and having me stand over the bike and seeing if I have difficulty riding the bike. This is my first new bike purchase in over a decade. My previous bikes were used ones that my dad got for cheap and one of them were an oversized mountain bike that I used to slant on a large angle in order to get on and ride. So I have gotten very used to an oversized bike.

I see threads about bike fitting that suggests that a person should have at least 1" clearance between your crotch and the top tube. While standing over my tube top, I barely avoid grazing the lower end of the sloping top tube. Certainly the clearance is very tight and too close for comfort. I don't seem to have problems with riding my bike (had to lower the saddle just slightly below the handlebar, with about 2" of seatpost visible between the saddle rail and the top of the seat tube) and I don't have any knee/back pains after riding 13 miles other than some hand numbness and perineum soreness.

So my question is, is the current bike right for me or should I be using the 17.5" frame which is the next size down? Looking at the size of the FX bikes, the standover length for 17.5" bike is 29.06" while the 20" bike is 30.9". I imagine with the 17.5" frame, the saddle would be adjusted higher and possibly need to add spacers to the handlebar to raise it so I don't hunch over too much.

What are everyone's thought?

DorkDisk

A 20" inch compact frame sounds too large for a 5-8 person. Im taller than you and would never consider a 20" frame

I would suggest getting the smallest frame you can get away with for nimbleness and standover. Its easier to make a slightly smaller frame fit, while a too large frame has no fix. Most beginners use frames way too large for them IMO

Its not "hunched over," its called a "flat back" position.

gpburdell

Let me guess, they had the 20 in stock and would have to order the 17.5?

With your size the 17.5" would be the most logical choice. I'm just slightly taller with similar inseam and have a 17.5" DS that's a great fit.

MRT2

I don't know. A picture is worth 1,000 words. Can you post a picture of yourself riding the bike? It may be your bike shop is correct, or maybe not. I am just over 5'8" and used to ride a Bianchi 18" hybrid, and over time, I concluded the frame was just a little too small for me.

FWIW, standover is overrated as a measurement of fit, IMO. If I bought a bike that allowed me an inch clearance from the top bar while standing flat footed, I would be riding a bike at least a size too small.

xionchen4628

I think they had the 17.5 in stock but the LBS guy thought it might be a bit small for me. Had me try the 20" 7.3 FX which I had no problem riding and then we went with that for the 7.2 FX.

xionchen4628

[QUOTE=MRT2;17847680]I don't know. A picture is worth 1,000 words. Can you post a picture of yourself riding the bike? It may be your bike shop is correct, or maybe not. I am just over 5'8" and used to ride a Bianchi 18" hybrid, and over time, I concluded the frame was just a little too small for me.

I will post a picture later this afternoon. Just want to make sure that my bike is the best fit for me even though the 20" seems to ride fine for me.

nakenergy

I am 5' 8 with 30 inch seam and just got a Trek FX 7.3; the LBS recommended 17.5 for me.

RedRockRider

I would say you are right between the 17.5 and 20, so it comes down to personal preference and how YOU like to fit on a bike. The smaller frame will result in a more aggressive posture.

Also (only since you mentioned other bikes your father bought you), are you still a growing teenager? That may have factored into the bike shop recommending the frame on the larger side.

xionchen4628

Thanks. That is what I figure too. I figure with the 17.5" frame, I would need to raise my saddle higher to get a nice fit, which would probably have me lean over more into a aggressive posture. A coworker of mine said something similar to me. I can probably go with either, depending on how I want to ride.

Nah, I am way past the teenager phase. It has been over a decade since I last owned a bike. This is the first NEW bike that I have ever brought for myself. That is why I am more anxious about making sure that I have the right fit before the 30 day exchange period runs out.

Wanderer

How did you feel when riding both bikes********** Are you so used to a bigger bike, that it felt more natural to you? I like to ride stretched out, so I have one too big, and one just right. The big one is more comfortable, the smaller one is easier to ride.

xionchen4628

The 20" frame isn't over-sized by much, just slightly bigger. It felt comfortable and easy to ride. I am going to try the 17.5" frame and see how that rides when compared to the 20" frame.

Vifam7

Certainly worth going back to the LBS, fiddle with the seat adjustments, and checking out the smaller size bike.

FWIW, I'm 5'75" in height with 30" in seam and my 7.3FX is size 17.5. I had an issue with hand/arm numbness but a few days ago I moved the seat to the rear and slightly down, and it seemed to have solved the problem.

Little Darwin

I am 6' tall, and for my height have a relatively short inseam... I ride a 20"2011 7.3 FX, and don't have much clearance when standing over the top tube. Part of it is that I am fat, so I am not as close to the seat as others when I stand.

However,, I wouldn't consider a smaller frame (for me) because the reach would be too close, and the position too aggressive for me. Honestly, if you did 13 miles after 10 years without being on a bike, and felt good other than your minor complaints, I think you have the right size... But, I could be wrong.

RedRockRider

FWIW when I bought my first "real" bike it was an FX7.4 - the shop owner eyeballed me for a 20".

I am 5'11" with a 32.5-33 cycling inseam.

It was an great first nice bike and opened my eyes to cycling. Once I bought clip in pedals and started riding 20-30 miles at a time I needed to raise the seat very high and flip the stem down to stretch out, so it ended up being a very aggressive position.

I now have an FX 7.9 in a 22.5 and it fits me much better. With the seat at the proper height the handlebars are almost even with the seat (maybe a 1" drop) - which is what I prefer on this type of bike.


In several years of cycling on road bikes also, I have come full circle from riding frames that were slightly
small, with a long seat post, to preferring slightly larger frames with more of a horizontal seat to bar position.

yashinon

I have a friend who is 'in-between", she tried both the 17.5 and 20" WSD frames. LBS suggested the 17.5, so she went with that size. I think it is personal preference. Standover is a guideline and meant for safety. If the bike is comfortable you can hold onto it. However, if you get the 17.5 frame, you can raise the seat and get into a lower position.

ColonelSanders

How is the less comfortable bike easier to ride?

steve_cay

I would say you are in between and possibly leaning towards the 17.5. Definitely try the 17.5 as well (make sure everything is adjusted right including seat fore/aft), and see which one feels right. Your shorts crotch probably ok to graze top tube, but your body parts should not be pressing on it for a hybrid.

MRT2

Not as strange as it sounds. I think I understand completely.

Wanderer

Easier to go faster, and handles better, just not as plush of a ride....

limbot

Don't use standover as the be all and end all of sizing. I'm 170cm ( 5'7") with a short in leg of 70 cm ( 28").

That being said though my torso and arms are much longer so for me Top Tube is more important in a fit.

On a roadie one shop fitted me based purely on standover and put me on a 48" bike. My current bike that fits properly is a 55" with a standover of 76 centimetres (30" )

My DS 8.4 is a 15.5" ( the smallest they make) and the standover listed is 73.8cm (29").

Based purely on standover I'd be riding a kids bike

So much depends on the geometry of the bike and your body shape and flexibility. You need to ride them to see what fits, you can't just base it on measurements.

xionchen4628

Thank you everyone for chiming in on the subject. I had a chance to try the 17.5" in the shop. In terms of standover height, in felt pretty similar compared to the 20" that I tried right next to it. I didn't see any big change in clearance. I need to adjust the height of the saddle on the 17.5" higher than the 20". I took a short ride in the parking lot and the 17.5" handles roughly like the 20".

The LBS guys basically echoed some of the comments made in this thread, I can use either 17.5" or the 20" frame, depending on how I want to ride and how comfortable I feel. Being that I took a couple of rides already on my 20", ranging from 6-13 mles and feel very comfortable on it, I plan to stick with the 20". If my LBS suggested 17.5 first and I rode with that, I would have been happy too.

rockrash

I am 5' 9 with 30 inch seam and just got a Trek FX 7.3 i was sized at 17.5. What will happen if you jump off your seat will cross bar hit ,

fietsbob

Down sloping top tube bikes size differently than a horizontal top Tube Bike Frame, thats why including a Virtual top tube* dimension helps.

* a horizontal line from head tube/steering axis<-> seat tube center line, where a top tube would Be.

Given 'size' is usually what people call the length of the seat Tube. BB to TT centerline , or tube-top, or highest point on seat tube.

Wanderer

If you want to be able to sit more upright, get the smaller bike. If you want to lean a little more, get the big one!

Crona

I am 5'10 and ride a 22.5" 7.3FX. I like the larger frame and dont have an issue clearing the top tube. It just seems more comfortable but less nimble. My bike store fitted on a shorter stem when I bought It which made all the difference for me. It went from a slightly large feeling bike to perfect.