Geometry lessons (Help!)- Mtbr.com

# Thread: Geometry lessons (Help!)

1. ## Geometry lessons (Help!)

I'm turning to you SS'ers for guidance, since you're all primarily a hardtail bunch.

I need some guidance on frame geometry. I'll be building a custom hardtail soon and I'm having trouble trying to best communicate what I want as far as angles and measurements.

See, my primary ride is a 6/5" geared squish bike. So how do I begin to communicate to a frame builder what I want? The riding styles are 180 degrees out. The questions come up such as How do you ride? What works for a full suspended squisher can't translate into a hardtail, right? The two types of riding are apples and oranges.

For example, climbing on my squish bike I do seated. Climbing on the SS I do standing.

About the only solid thing that I can come up with is BB height. But even that can't work as a hardtails ride height doesn't move as a fully's does.

The time that I've spent on the FrankenCruiser gives my some ideas of what works and what doesn't, but that frame is way too small for me, and people have commented that running the Talas at 130mm can't really be the hot setup.

So, you see I really don't have a solid frame of reference.

Have any of you come off of a squishy and then had a custom bike done? What would you have done differently?

I'm confused. Any ideas?

2. Talk to the builder about the kind of riding you do, they should be the ones with the experience to translate that into frame geometry for you.

3. I almost got a custom frame a year or so ago. I had no idea what I wanted, though. The builder was kind enough to recommend that I get some stock frame that was close to what comes out of some fitting computer program, ride that for a season, and let him know what I like and dislike about it.

I figured out the starting toptube and stem length (your basic size 'large'). Then I learned that I like my bars even with my saddle.
I know that I like a longer top tube.
I still have not gotten a custom frame, but it helped a ton to just ride something first. I would get a little longer toptube, and sloping so I don't run my wierd riser stem and bars. I also wish my saddle was a little further back sometimes.

You might just try out some buddys' bikes. I did this, too. Make sure you measure them, also. So when a bike feels too cramped or too laid out, you have some numbers to give the builder. That's usually enough for a good builder: a bike and how you felt about it and you can often get the full numbers from the manufacturers website. Ride bikes that are just obviously wrong, too. You might actually like one of them!

just a suggestion...

4. ## try a rigid fork

Originally Posted by Aquaholic
I'm turning to you SS'ers for guidance, since you're all primarily a hardtail bunch.

I need some guidance on frame geometry. I'll be building a custom hardtail soon and I'm having trouble trying to best communicate what I want as far as angles and measurements.

See, my primary ride is a 6/5" geared squish bike. So how do I begin to communicate to a frame builder what I want? The riding styles are 180 degrees out. The questions come up such as How do you ride? What works for a full suspended squisher can't translate into a hardtail, right? The two types of riding are apples and oranges.

For example, climbing on my squish bike I do seated. Climbing on the SS I do standing.

About the only solid thing that I can come up with is BB height. But even that can't work as a hardtails ride height doesn't move as a fully's does.

The time that I've spent on the FrankenCruiser gives my some ideas of what works and what doesn't, but that frame is way too small for me, and people have commented that running the Talas at 130mm can't really be the hot setup.

So, you see I really don't have a solid frame of reference.

Have any of you come off of a squishy and then had a custom bike done? What would you have done differently?

I'm confused. Any ideas?
I think you should maybe try a cheap rigid fork, Surly or Kona, from there you should notice a bit quicker steering bike, and maybe you'll even like it and be able to climb on it.
It looks about as choppered out with that fork as my 24" bmx cruiser looked like when I tried to put a 80mm zoke z2 atom 80 on it. It rode cool down hill and over jumps, but any slight up hill rise or even needing to sit on the seat and it totally sucked.
I had a custom geared cross bike made and I just slightly altered the geometry of my Surly cross check, 1/2 degree steeper head angle, cause it's now my road bike also, I probably should have dropped the BB a little, to add a little more high speed stability, but it does ride great, a little nervous off road at speed sometimes, and sometimes on the road at very fast down hill speeds, about 45mph and faster you have to concentrate some as well. But I'm getting used to it and really like it.

5. ## Maybe not too different!

S-

Except for BB height, which will be lower as you pointed out, maybe your ideal XC hardtail isn't going to be too different from your Turner.

My SS hardtail and my squishy bike have the same top tube length and head tube height. The handlebars are about the same place below my saddle. I run the same length stem on both, 120mm. If I wanted my squishy to be more upright for better descending capabilities, I might go to a 100mm, but I wouldn't change the frame size.

My advice: Use your Turner top tube length as a starting point and check out XC bikes with similar top tube length/stem combos. Considering just how much you love that bike, you can't go too far wrong.

JMH

Originally Posted by Aquaholic
I'm turning to you SS'ers for guidance, since you're all primarily a hardtail bunch.

I need some guidance on frame geometry. I'll be building a custom hardtail soon and I'm having trouble trying to best communicate what I want as far as angles and measurements.

See, my primary ride is a 6/5" geared squish bike. So how do I begin to communicate to a frame builder what I want? The riding styles are 180 degrees out. The questions come up such as How do you ride? What works for a full suspended squisher can't translate into a hardtail, right? The two types of riding are apples and oranges.

For example, climbing on my squish bike I do seated. Climbing on the SS I do standing.

About the only solid thing that I can come up with is BB height. But even that can't work as a hardtails ride height doesn't move as a fully's does.

The time that I've spent on the FrankenCruiser gives my some ideas of what works and what doesn't, but that frame is way too small for me, and people have commented that running the Talas at 130mm can't really be the hot setup.

So, you see I really don't have a solid frame of reference.

Have any of you come off of a squishy and then had a custom bike done? What would you have done differently?

I'm confused. Any ideas?

6. Thanks for the feedback, guys! Wassup JMH!!??? I think that it must be so much easier for those of you that have years of experience on hardtails. After a bit of trial and error, you pretty much know what works for you and what doesn't.

I really struggled with the decision of 29" wheels alone. I'm just overly skittish about investing a lot of bones in a custom build and getting it wrong.

Being 14 feet tall, I don't know a lot of people with bikes big enough for me to spend time on and fully evaluate.

7. ## Try This

I found a in expensive frame on ebay,and converted it to a single with a bunch of used parts. I road it around for about 3 months. It give me a good idea of what I liked and did not like. It was a new Haro that I got for \$50.00. I think I paid more for the chain tensioner than I did for the frame. After I got my new single I was able to sell everthing, and for the most part got all my \$\$\$ back.

8. Originally Posted by Aquaholic
T

Being 14 feet tall, I don't know a lot of people with bikes big enough for me to spend time on and fully evaluate.
ahh.. I see. also makes it tough to try out a production frrame that might be close.

9. ## trust the builder

Originally Posted by Mine'sAQuart
Talk to the builder about the kind of riding you do, they should be the ones with the experience to translate that into frame geometry for you.
ditto that.

give them your measurements and riding styles and they will know. I jumped in with Curtlo that way and couldn't be happier with my frame.

You're not *that* different from most other dudes.

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