Questions tagged [geometry]

Questions concerning the angles, tube lengths, and other measurements of the bike frame.

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38 votes
7 answers
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What is the difference between a horizontal top tube and a sloped one?

Some comparable bicycles have a crossbar (top tube) that's horizontal: Others have one that's sloped: What are the reasons for either frame design? Is it merely style preferences? Or is there more ...
Matt's user avatar
  • 742
32 votes
3 answers
8k views

Why Did Old Soviet City Bikes Have Longer Frames in General

Yesterday I got my hands on an old soviet city bike "Ukraine". It was produced in Kharkov velo factory, 1987. I could not help but notice that the bike frame has different geometry compared ...
Badan's user avatar
  • 421
30 votes
5 answers
17k views

Explaining the effects of frame geometries

I asked about buying a bike here, and someone asked on my behalf about test-riding a bike before buying. My question is, what should I know, or should have known, about the sizing or 'geometry' of a ...
ChrisW's user avatar
  • 12k
21 votes
5 answers
82k views

Touching the front wheel with my foot when turning

My girlfriend got a new city bike today and she touches the front wheel every time she has to make a hard turn. Is there anyway to avoid this besides replacing the whole bike? LATER EDIT: I think I ...
Paul Irofti's user avatar
18 votes
4 answers
40k views

What effect does head tube angle have on a bicycle?

My girlfriend and I are looking at a new bike for her. The one we're looking at has a 70 degree head tube angle while her current bike has a 70.5 degree head tube angle. Unfortunately, none of the ...
jimchristie's user avatar
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16 votes
6 answers
13k views

What happened to riding with no hands?

I remember, as a kid in the seventies we were able to ride blocks without ever touching the handlebars. Today, I only see road-bikers riding without hands - and this is rarely. I almost never see ...
Wes's user avatar
  • 331
14 votes
1 answer
9k views

How is stem length (reach) measured?

How is the length of a stem measured? Where does the measurement start and finish?
Martynnw's user avatar
  • 1,407
11 votes
2 answers
3k views

How does fork offset affect bike handling?

Some forks come in a variety of different fork offsets for the same model. How does replacing the fork designed for the bike with: A fork with smaller offset, everything else the same A fork with ...
abdnChap's user avatar
  • 3,339
11 votes
3 answers
20k views

Does inseam of pants convert to stand over height of a bike?

If I know my jeans size, for instance 32", 32", can I convert this into an estimate for standover height on a bike?
mfg's user avatar
  • 938
10 votes
3 answers
23k views

How does a chainstay length affect a mountain bike performance? (wrt: 26", 650B, 29r)

The trade offs for 26" through to 29" with respect to rolling resistance, contact patch, obstacle rollover, etc... have been well discussed. However, it occurs to me that as the rear wheel gets larger ...
JeffV's user avatar
  • 347
10 votes
3 answers
1k views

Were older bikes generally longer?

Tl;dr: Were bicycle frames in the mid-20th century generally longer than today? This post asked about the length of a Soviet bike from the 1980s. The frame is longer than that of a contemporary bike ...
Peter - Reinstate Monica's user avatar
10 votes
1 answer
693 views

S shaped down tube (MTB)

Are there any advantages of S shaped down tubes over the traditional ones on MTB? For example: what do you think of this design? Jamis Exile Comp 2013
Vladimir's user avatar
  • 203
8 votes
3 answers
24k views

What benefits does a tapered head tube afford?

I've just read a review of Tom Zirbel's Jamis Xenith SL on Bike Radar and flicking through the pictures there is one of the head tube with the following caption: Tom Zirbel's (Jamis Sutter Home) ...
Greg B's user avatar
  • 1,263
8 votes
2 answers
1k views

How to choose between a race bike like a Madone and a classics bike like a Domane

I ride regularly for exercise in New York City but do not race. I currently ride on a steel frame that handles the rough roads easily. I want to buy a carbon bike and am torn between a "classics" bike ...
Bradford Burnham's user avatar
8 votes
1 answer
1k views

Cycling jargon: "relaxed geometry", "slack geometry", and "aggressive geometry"

In one sentence… What is the meaning (and for which parts), the implications, and, if possible, the etymology of these three terms? In more words… When I hear this bike has more aggressive geometry ...
Sam7919's user avatar
  • 9,112
7 votes
4 answers
2k views

Apparent pedal force improvement from swept back handlebars; why not use them?

As a teenager a friend found some antique swept back motorcycle handlebars that had the same expansion nut type fitting as my bike and we had to try them out; the handles just touched the front of the ...
Ken Fabian's user avatar
7 votes
4 answers
3k views

What makes a bike good or bad for climbing?

For example, is this a good climbing bike? Can I have your general thoughts about the bike geometry? I know it is an aero frame but do you think it would be also good for climbing?
Ender's user avatar
  • 1,950
7 votes
2 answers
3k views

Are bikes with aggressive positions required to achieve high fitness levels when training on a bike?

Are bikes with aggressive positions required to achieve high fitness levels when training on a bike? My bike fitter claimed that a more aggressive posture is better for transferring power than a more ...
Brian's user avatar
  • 1,043
7 votes
2 answers
16k views

What effect does seat tube angle have?

I know that head tube angle affect steering, but does seat tube angle affect maneuvering somehow? As long as I compare a few models, they are between 72 and 74 degrees, and greater the frame smaller ...
Maz's user avatar
  • 73
7 votes
1 answer
766 views

Typical and minimum ground-pedal clearance

What is the typical and generally accepted minimum clearance between the ground and pedal? Does this vary between different bike styles (road, gravel, mountain)? I've read that designs with low ...
Edward's user avatar
  • 372
6 votes
6 answers
11k views

I sit real far back on my saddle

Asked this on diaspora, but was urged to come here, so, here's my question: I tend to slide BACK on my saddle really far, to the point where my sit bones are very near to the edge. If I try to scoot ...
lokeen's user avatar
  • 61
6 votes
1 answer
187 views

How does the frame geometry of a cyclocross bike affect its performance in off-road conditions?

The frame geometry of cyclocross bikes aims to offer a responsive and agile feel while providing stability and control over mixed surfaces. It allows riders to handle the demands of cyclocross racing, ...
Arunabh Bhattacharya's user avatar
6 votes
2 answers
5k views

How does the geometry of cross bikes affect on-road handling?

I'm planning on getting a cyclocross bike for commuting because my road bike is suboptimal for riding in rain and snow. A bike shop employee told me that cross bikes have worse geometry for riding on ...
amcnabb's user avatar
  • 7,095
6 votes
1 answer
157 views

Help me choose a new bicycle size having different geometry

My current bicycle is Triban RC 500 size L (56): https://www.decathlon.co.uk/p/road-bike-triban-rc-500-disc-brake/_/R-p-308097 My hight is 185cm by leg inseam is 90cm. I am looking to buy Bianchi ...
Steve's user avatar
  • 161
6 votes
2 answers
6k views

Is there much of a difference between flatland and park/street frames?

I am a newbie at biking, and I've been wanting to get into BMX for a few years, and I can now since I actually have some money. Primarily I've been wanting a 20" BMX bike with front and rear brakes ...
cutrightjm's user avatar
5 votes
4 answers
2k views

BB drop vs BB height from stability perspective

While I have heard that a lower bottom bracket tends to give more stability, I'm confused as from which point of reference yields such an effect, from the wheel axle (BB drop) or from the tire contact ...
Gregory Leo's user avatar
  • 1,295
5 votes
2 answers
3k views

Comparing 'upright-ness' across several endurance road bikes

I'm comparing the following endurance road bikes, all in 58cm or L: BMC Roadmachine Cannondale Synapse Trek Domane Look 765 Optimum Specialized Roubaix I'm 6'2" and recently recovered from a ...
Brad Solomon's user avatar
5 votes
2 answers
4k views

How to stop foot clipping front mudguard

My feet overlap the pedal and clip the front mudguard when I'm turning at a low speed because I have to turn the handlebars wider than normal. My foot doesn't clip the wheel when the mudguard is not ...
PhilJ's user avatar
  • 433
5 votes
2 answers
701 views

tall bike build

Hi everyone just a silly question. I have built a tall bike which is a wee project at the moment. I live in a hilly area in Scotland and having gone down a hill at 25 mpg (40 km/h) on the beast. I ...
robert45's user avatar
5 votes
2 answers
1k views

New MTB makes it feel like too much weight on arms? How do I make it better?

My 10 year old montain mountain bike has quite an upright seating position and front tyre, which is what I think makes it very comfortable to ride for long periods of times. Having recently bought a ...
KillerKode's user avatar
4 votes
3 answers
1k views

Bike fitting experiences

I just recently went through a Specialized BG Pro-Fit (was about $200), and have to say that I'm super happy with the results and experience. The fitter was telling me about some others out there ...
fady's user avatar
  • 507
4 votes
3 answers
399 views

Confused about the actual difference between flat-bar hybrid and endurance road geometries

I’ve been riding a Specialized Ruby (basically a Roubaix) for over a year, but just had major back surgery (lumbar fusion of 3 disks) and my surgeon suggested I change to a more upright hybrid frame. ...
AstroBen's user avatar
  • 169
4 votes
2 answers
8k views

Front wheel lifting on climbs on my Mountain Bike

I've got a full suspension XC/AM 29er mountain bike (Gary Fisher Hi-Fi Pro). I'm running a size small frame with an 80mm stem with about 7 degree rise. Bike seems like a good fit for me. I do run the ...
Benzo's user avatar
  • 18.2k
4 votes
3 answers
486 views

Can a bike fit compensate for 10-30mm deviations in reach and stack from a known, comfortable bike?

I find the Trek FX Sport 4 to be comfortable but much less fun to ride than the Specialized Sirrus 4! Unfortunately, on the Sirrus I feel like I'm arching my back and want to reach further forward. ...
Peachy's user avatar
  • 125
4 votes
1 answer
4k views

Geometry between 50mm stem and a 65mm stem and riding experience

Will I notice much difference beside just having a slightly longer cockpit between my seat and fork if I upgrade from a 50mm to a 65 mm stem? is this 15mm a significant enough adjustment to make my ...
sov's user avatar
  • 333
4 votes
2 answers
480 views

Why can compact frame in road bikes be made in less sizes than the traditional frame?

When I read about Giant, they talked about how in the past road bikes have to be in like 10 incremental sizes, but Giant had an idea from a mountain bike (which usually only have S M L sizes) to make ...
Rizki Hadiaturrasyid's user avatar
4 votes
1 answer
134 views

Which geometry specifications determine the seating position of an MTB?

MTB manufacturers release geometry data for their bikes. If I want to know if a bike has a more upright or stretched position, which geometry data do I have to compare?
JohnnyFromBF's user avatar
4 votes
1 answer
5k views

What would be the "definitive" formula to calculate chainstay length from sprocket size, chainring size and number of chain links?

Before I started to write this answer, I thoroughly read this question, its answers and comments: How do I calculate the diameter of a chainring from the number of teeth? So, my question tries to ...
heltonbiker's user avatar
4 votes
1 answer
371 views

How to find a frame given a geometry

In 2007, I bought my first bike: a Bianchi Boardwalk 2006. It was a great bike, but I didn't treat it well and it now needs about $300 worth of work. I've been thinking that maybe I'd like to take ...
SteveH's user avatar
  • 41
4 votes
1 answer
190 views

Fork offset vs angle -- what is the difference in steering

When you read such post as this one https://bikeinsights.com/cyclopedia/trail you will learn how offset and head tube angle affects steering. But I wonder about those parameters in "reverse" ...
greenoldman's user avatar
  • 2,064
4 votes
1 answer
193 views

Effect of trail on riding fakie

How does trail affect the steering of a bicycle when riding backwards? Is a bike with a longer trail easier to ride backwards than a bike with a shorter trail (ex: track bike)? I understand when ...
Fixedgearrider's user avatar
4 votes
1 answer
2k views

Are there geometrical differences between framesets optimised for flats vs drops, other than top tube length?

Question background: I am on the cusp of buying a 'do it all' bike for commuting and light touring. The bike i'm looking at (Genesis Croix de Fer 2015 model) comes with drop handlebars. I would like ...
Rich's user avatar
  • 41
3 votes
4 answers
1k views

Why don't race bikes have solid front triangles?

I know that cutting material out makes a bike lighter, but at some point there must be a crossover between weight and aerodynamics. Since tri-bikes and track bikes have more oval/flat shaped tubes, ...
Aaron's user avatar
  • 5,067
3 votes
2 answers
841 views

Can large bike size will be solved by replacing the crank arm with a longer length?

I recently bought a carbon fiber bike and the size is a bit big, it's sava phantom3.0 56cm ,but I love the bike and don't want to wait too long for small size bike, would a longer crank arm be a good ...
Alexander Gary's user avatar
3 votes
2 answers
736 views

Why do current mountain bikes have such steep top tube? Comparing my Kona Blast 2001 vs 2019

I am very curious about the geometries of mountain bikes nowadays (or probably since a while back). They all seem to have very tilted top tube .. compare my Kona Blast 2001 vs 2019 Kona Blast 2001 ...
Edmund Fong's user avatar
3 votes
2 answers
2k views

Install suspension forks on non-suspension bike

I have a 1990s Saracen PowerTrax. Is there a way I can install a suspension fork, or will that muck up the bike somehow? I'm actually interested in ways to raise the bars with respect to the seat, so ...
Neil Barnwell's user avatar
3 votes
3 answers
15k views

25 degree rise stem vs 6 degree rise stem with taller head tube - how is handling affected?

All, I’m shopping for a new road bike with endurance geometry (more upright position and shorter top tube), 9mm drop saddle-to-bars. I’ve had a Guru fit done by a professional fitter. The main ...
North Krimsly's user avatar
3 votes
2 answers
954 views

Are flat handlebars stable at high speed?

I live in a mountainous area, and so there are lots of opportunities for descending at high speed. I currently have a bike with drop bars, and when in the drops, I feel very stable doing this. I am ...
Reid's user avatar
  • 1,538
3 votes
1 answer
530 views

On WSD bicycle shouldn't the seat tube be longer and at a shallower angle?

I bought a WSD ("Women specify design") bicycle for my wife which was delivered in a box. After putting it together I took it for a ride to test it and I realised two things. The seat tube ...
MindDBike's user avatar
  • 366
3 votes
1 answer
516 views

Striking pedals on a full suspension bike

I just change my old hardtail (Marlin 5-TREK) for a full-suspension bike (Siskiu D7). The bike runs smoothly, but I notice how frequently strike my pedals with the ground and other obstacles. I ...
Jonathan Pacheco's user avatar