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Frame size help

705 Views 6 Replies 3 Participants Last post by iviguy, Apr 21, 2005

Discussion Starter · Apr 14, 2005

Sup all, I'm new here.
I've been out of biking for 4 years now. I recently started riding again and wanted to make some upgrades like tubeless tires, and disc brakes. When I started adding up the costs I figured I better just get a new bike and since I kinda want a full suspension anyways it was an easy decision.

My problem is I'm not sure what size frame to go with.
For a full suspension do you need more room over the top tube?
I've always felt as tough my hardtail was a little big and I may be between sizes. Standing over the bike centered on the top tube I touch. I have a 17.5" frame now with a 29-30" inseam and I'm 5' 8". I do XC riding,I'm not sure if this matters. I plan on upgrading from my Trek 8500 to a Trek fuel.

1 more question does having a shorter wheel base effect your riding enough to where it's something you need to consider?

Any help will be greatly appreciated! Thanks in advance

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Orthie251

· #2 · Apr 17, 2005

Go by top tube length...

With your height, you should probably be looking at a Small / 15" frame. That should provide enough clearance vertically. However, remember that each manufacturer uses these measurments in a different way. The crucial measurement to go by is top tube lenght. I suggest you test ride several bikes and base your decision on how they handle, but use for comparison the top tube length.

If you'd like a bit more guidance, check the Santa Cruz website (www.santacruzbikes.com), select any model and go to sizing. They will show their recommended size and stem length (it's probably based on loose averages) for your height.

Nothing beats test riding bikes, though, plus the advise and fit of a good LBS.

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slowrider

· #3 · Apr 17, 2005

size

I'm 5'6" with a 28" or so inseam and my 5 Spot is a Medium 17 ( W 23" TT, 75mm stem) with the standover of a 15". Standover is More important in technical situations where it inspires confidence. I think most Mediums(17") will work best for you but it varies from one manufacturer to another. The shorter wheelbase can help in the tight trails while longer wheelbase's are more stable at speed. But wheelbase can be gained in frame length or fork rake and doing so by fork rake slows handling a little more than doing so by frame length. The slacker head angle works for me but opinions differ. Different suspensions make a difference as well. I like the Horst/FSR's better for the active suspension but the VPP and high single pivot design's are snappier at the cost of some quirky suspension traits. Try what you can and by what you like. Good luck.

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Orthie251

· #4 · Apr 17, 2005

slowrider said:
I'm 5'6" with a 28" or so inseam and my 5 Spot is a Medium 17 ( W 23" TT, 75mm stem) with the standover of a 15". Standover is More important in technical situations where it inspires confidence. I think most Mediums(17") will work best for you but it varies from one manufacturer to another. The shorter wheelbase can help in the tight trails while longer wheelbase's are more stable at speed. But wheelbase can be gained in frame length or fork rake and doing so by fork rake slows handling a little more than doing so by frame length. The slacker head angle works for me but opinions differ. Different suspensions make a difference as well. I like the Horst/FSR's better for the active suspension but the VPP and high single pivot design's are snappier at the cost of some quirky suspension traits. Try what you can and by what you like. Good luck.

With all due respect, I believe that a 75 mm stem is in general, too short, and means that the frame is a bit on the large size. In general, for optimal handling, the stem should be between 90 and 120 mm if the frame is sized correctly. Check out Zinn's new cycling book that devotes a lot of pages to the subject of optimal bike fit. With a correctly sized frame, standover height is usually not an issue. For your height, I believe a 15"/Small frame would be even better. In general, when one is between sizes, the smaller size is more agile and has better handling than the larger size. In terms of overall seat to handlebar distance, they can both be the same since the larger frame will require a shorter stem. I am 5' 11" and ride a medium Titus Racer-X with a 23.25" top tube and a 120 mm stem, but my Cannondale hardtail is a large frame with a 24.3" top tube and a 100 mm stem. In both I have the same reach.

A longer stem will slow down the steering vs. a shorter stem. A longer stem will position the rider more optimally for climbing while a shorter stem is more optimal for descending.

Bike fit is a series of compromises depending on riding style, fitness, and so on. We could go on forever... while riding our bikes and having fun!!!

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Discussion Starter · #5 · Apr 18, 2005

Thanks much for the replies!

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slowrider

· #6 · Apr 21, 2005

Sizing

Orthie251 said:
With all due respect, I believe that a 75 mm stem is in general, too short, and means that the frame is a bit on the large size. In general, for optimal handling, the stem should be between 90 and 120 mm if the frame is sized correctly. Check out Zinn's new cycling book that devotes a lot of pages to the subject of optimal bike fit. With a correctly sized frame, standover height is usually not an issue. For your height, I believe a 15"/Small frame would be even better. In general, when one is between sizes, the smaller size is more agile and has better handling than the larger size. In terms of overall seat to handlebar distance, they can both be the same since the larger frame will require a shorter stem. I am 5' 11" and ride a medium Titus Racer-X with a 23.25" top tube and a 120 mm stem, but my Cannondale hardtail is a large frame with a 24.3" top tube and a 100 mm stem. In both I have the same reach.

A longer stem will slow down the steering vs. a shorter stem. A longer stem will position the rider more optimally for climbing while a shorter stem is more optimal for descending.

Bike fit is a series of compromises depending on riding style, fitness, and so on. We could go on forever... while riding our bikes and having fun!!!

I aggree with you when dealing with someone new but I've tried a ton of frame designes over the last 12 years and once I tried Gary fishers Genisis (I think) Geometry I found I liked it much better than a traditional set up. It gives me the feel of rotating the bars around the steer tube rather than the traditional tiller like swing through an arc out on the end of a 120mm stem. A highly personal fit but it's the one I like.

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iviguy

· #7 · Apr 21, 2005

Woolfe said:
Sup all, I'm new here.
I've been out of biking for 4 years now. I recently started riding again and wanted to make some upgrades like tubeless tires, and disc brakes. When I started adding up the costs I figured I better just get a new bike and since I kinda want a full suspension anyways it was an easy decision.

My problem is I'm not sure what size frame to go with.
For a full suspension do you need more room over the top tube?
I've always felt as tough my hardtail was a little big and I may be between sizes. Standing over the bike centered on the top tube I touch. I have a 17.5" frame now with a 29-30" inseam and I'm 5' 8". I do XC riding,I'm not sure if this matters. I plan on upgrading from my Trek 8500 to a Trek fuel.

1 more question does having a shorter wheel base effect your riding enough to where it's something you need to consider?

Any help will be greatly appreciated! Thanks in advance

I have a friend that's about the same size as you in all respects you mentioned. He is riding on a Hardrock Medium frame and it seems to fit him well. As far as the dual suspension question, I don't think sizing for dual is different than a HT. Best thing to do is test ride it at your LBS and then make sure that they will help you with the sizing after you buy the bike from them. Most usually will.

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