Questions tagged [geometry]

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

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What do "capsize", "wobble", and "weave" mean when referring to bike stability?

Some research into (uncontrolled) bicycle stability (e.g. Jason K. Moore, Human Control of a Bicycle, 2012) models the dynamic behavior of some bikes and determines "critical speeds" for &...
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  • 241
2 votes
0 answers
87 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 ...
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2 votes
0 answers
105 views

Effect of 90 degree head angle (vertical steering axis) - zero flop

Are there any two-wheel bicycles with 90 degree head angle? The trail would be determined by fork offset alone, i.e. it would be a caster wheel. Related: What effect does head tube angle have on a ...
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147 views

Is a shared bolt between the rear shock mounting and rear swing arm ok?

I'm buying this for my brother mainly for deep-snow riding. The rider weighs about 120 kg (265 lbs). 26" x 4" (102mm) tires in the pictures, but I will install 26" x 4.8" (122mm) ...
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-1 votes
3 answers
204 views

Is this frame/bike suitable for a heavy rider?

Here is one frame I am looking at, just for normal gravel road riding but I´m quite heavy rider currently around 331 lbs (150 kg). Need help looking for issues with this frame.
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6 votes
4 answers
2k 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?
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3 votes
1 answer
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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 ...
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0 votes
1 answer
132 views

buying bigger frame to get less aggressive geometry

If I like a model of bike (looking at giant TCR 2) but the sitting position of the bike is a little too aggressive for my liking i.e. too bent forward instead of upright, is buying a slightly bigger ...
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2 votes
2 answers
3k views

Why are endurance bikes so bulky or wide nowadays?

I have been visiting lately some shops checking for a new endurance bike and at the same trying some more "racy" models. For example by Canyon or by Rose. I really like the race models, but ...
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5 votes
2 answers
351 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 ...
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2 votes
1 answer
134 views

Bike fit - comparison of similar geometries

I'm usually riding my hybrid Giant Roam but recently I've been given a 2nd hand Decathlon 27.5 MTB for free and I've started hitting some mountain bike roads (not trails, more like forest paths, fire ...
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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 ...
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5 votes
2 answers
868 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 ...
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2 votes
1 answer
274 views

Are Adjustable Stems With Reasonable Merit?

[Question overhauled after I realised it appeared snobbish, narrow and not in good faith, as pointed out by @gschenk . This sentiment originated due to a recent failure with a critical bolt mechanism ...
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9 votes
2 answers
1k 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 ...
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0 votes
1 answer
541 views

Are bikes with sloping top tubes lighter than bikes with horizontal top tubes?

For many years bicycles nearly universally had horizontal top tubes, but that has changed: now most bicycles have "compact" geometry, with top tubes that slope downwards from front to back. ...
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3 votes
1 answer
405 views

In bike geometry, what is 'RC Length'?

For example, seen on the Reid Cycles website
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4 votes
2 answers
333 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 ...
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1 vote
2 answers
988 views

Geometry question: shorter stack with same reach?

I'm planning on building a new bike soon but I'm quite conflicted about choosing a frame. For now I'm riding a GT Grade AL 2015 that I use everyday to commute but since I'm planning on doing some ...
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1 vote
1 answer
212 views

Upgrading a dual sport bike - a geometry question

I want to ask a somewhat general question in the context of actual events: I picked up an Evo Swift Ridge 7 for about 200 from a discount retailer, thinking it might be a good platform for upgrade-as-...
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3 votes
2 answers
409 views

How much flexibility is normal for steel frames?

I have an 1980ies steel road bike which I used to ride clipless pedals on. I have recently switched to platform pedals for commuting and found out that when I'm coasting and move my feet left and ...
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2 votes
1 answer
298 views

What do I need to make this new fork aesthetically pleasing?

I needed to replace my broken Bontrager Satellite Plus carbon/aluminum fork on my '05 Trek 1000. I chose this Q2 carbon/ aluminum fork as a replacement because the few Satellite Plus forks I was able ...
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3 votes
2 answers
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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 ...
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1 vote
1 answer
139 views

Replacing broken road fork with same model but shorter steerer tube. What can I expect for handling issues?

My road bike is an '05 Trek 1000 54 cm frame size. The Bontrager carbon fork (Satellite Plus) was destroyed in a non riding accident. I have found on eBay a replacement fork--same model , identical ...
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0 votes
0 answers
242 views

How many degrees does the stem of a Canyon integrated cockpit rise?

I am plotting a Canyon Ultimate bike on BikeCad, but I can't find how many degrees the stem rises. The stem is part of the Canyon H36 integrated cockpit. In general, manifacturers of integrated-stem ...
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1 vote
2 answers
3k views

What is the typical angle between the derailleur post (seat tube) and top of chain?

I'm building a (non-standard) bike and that means mounting a front derailleur in relationship to the incoming chain line (rather than selecting a seat-post angle visavis chainstay angle, etc.) So I'm ...
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0 votes
1 answer
2k views

Bike size advice Bianchi vs Cannondale

I have been after a Bianchi Via Nirone 7 for more than one month and an half without much success. The main reason is that they don't produce many 47cm frames, while 47cm would be my optimal size. In ...
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1 vote
1 answer
2k views

Effect of raising handlebars on a fat bike

I am currently demoing a 2019 Cannondale Fat Caad 2. Never owned a fat bike before. This bike is relatively light and they are on clearance right now at a local bike shop that I ride with and do ...
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3 votes
2 answers
626 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 ...
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0 votes
1 answer
72 views

Why the vertical difference between the right-most point of TT and the left-most (union with ST) is not part of a geometry chart?

One of the things I often look to determine whether a bike fits a specific purpose is that distance mentioned in the title, that is, if you draw a line from the stem to the seat tube, and then you ...
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1 vote
2 answers
2k views

Large vs small stack & reach

I'm looking at getting a new bike, but struggling with the most suitable one given the different geometries. Given a particular torso angle, is there an optimal stack & reach? A large S&R ...
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3 votes
1 answer
2k views

Should I prioritise reach over stack (in choosing a new bike)?

I'm in progress of choosing a new bike (or more specifically trading my MTB for a CX), and have asked for a CX with stack and reach numbers fitting my current road bike, an BMC GF01 'endurance' bike (...
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7 votes
2 answers
2k 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 ...
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1 vote
3 answers
2k views

Evaluating hybrid bike geometries

I am planning to buy a hybrid bike and have been evaluating a few geometries. Merida Speeder 100 Juliet 2018 Cannondale Quick 5 Disc Women's 2018 Marin Terra Linda 2 2019 Trek Zektor 2 2018 ...
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1 vote
1 answer
335 views

Stack measurement help

I'm trying to determine where I fit on the Cannondale Slate geometry because it doesn't seem they use top-tube actual or seat tube, but rather they're using the Stack? I see a great sale on a 56cm ...
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  • 113
3 votes
1 answer
5k views

Run 26" wheels on a 29er

I recently bought an 13.5 Trek Cali for my daughter (9 years old). I got an incredible deal on it and bought it sight unseen from an out of town seller. After getting it, I realized it had 29" ...
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  • 228
5 votes
2 answers
543 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 ...
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1 vote
3 answers
3k views

Relation formula between fork length change to headtube angle and bottom bracket height

As we know, changing the fork length will change bike geometry a bit. For example, increasing fork travel by 10 cm will make the headangle slacker and raise the bottom bracket. I consider to increase ...
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  • 1,703
2 votes
1 answer
4k views

Mino quick link geometry adjustment, what can I do with it?

My 2017 Trek Fuel EX 5 has a Mino quick link in the rear triangle, but I don't understand what position I should put it in. Could somebody explain what purpose each position is best suited for, e.g., ...
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  • 1,056
0 votes
1 answer
2k views

Desirable maximum steering angle

Zero means going straight, 90+ degrees is probably impossible. So what is the maximum steering angle needed to ride safely?
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2 votes
1 answer
953 views

Can I use my Endurance bike for my first race?

I recently got into road cycling, my first and only bike purchase has been a Scott endurance bike. Now that I am getting more and more comfortable on a road bike, a couple of guys I group ride with, ...
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15 votes
6 answers
12k 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 ...
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  • 321
2 votes
2 answers
3k views

How differently will two bikes handle that have 1 degree difference in their head tube angle? [duplicate]

I am looking to buy a new mountain bike and comparing two models with different head tube angles. How big of difference does 1 degree of slackness make? Would an intermediate rider be able to feel ...
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2 votes
3 answers
909 views

Bottom Bracket Height

I am just wondering if BB height from the ground is the same for all bikes or for all mountain bikes, all road bikes, etc? Or does every brand have its own design for that dimension?
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  • 539
2 votes
1 answer
426 views

Fork trail vs chainstay length in steering

Is fork trail or chainstay length is a bigger determinant in the overall steering of the bike? Consider an arbitrary frame that I think is steers too slowly. I'm going to rebuild it because I want a ...
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  • 5,244
3 votes
3 answers
13k 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 ...
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3 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 ...
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-3 votes
4 answers
1k views

Where should pedals be located?

I've noticed that while riding, whether uphill, downhill, or on a flat, if I move my body to the front of the saddle to where the pedals are behind me, pedaling is much easier. I'm not sure if it's my ...
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3 votes
1 answer
197 views

Understanding the bike geometry through riding [closed]

Though this question has been asked a lot of times, and there are very good answers out there, all the answers talk about the effect of individual parameters in isolation. That is, they take trail, ...
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  • 83
4 votes
2 answers
7k 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 ...
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