0

There are two questions here really though they both have to do with fit.

Today I tried a Baad Raad electric fat bike. This question isn't about batteries or fatties. I just wanted you to know this bike will be used on rough trails, snow and whatnot.

Baad Rad Electric Bike

The question is about fit. This is a one size fits all bike. The frame is said to be a large one. It seems to be about ninteen inches. I am six foot two. I tried the bike out and was pleasantly surprised as far as performance is concerned. When in pedal assist it does exactly what I want it to do and more.

Do some bikes have shorter cranks on them? I could still put up the seat more no problem. The cranks feel short to me. Is that because the seat should be raised? Is there more to it than that?

What about the handle bars? My mechanic says they can be raised as well. Will that affect how the bike fits as far as legs are concerned?

The price is more than right if I can tweak the fit a bit.

  • 4
    How would we know if a bikes we've never seen can be set up to fit a person we don't know? And I'm confused by your crank/seat height questions. Normally, you set the seat height so your leg's not quite straight with the pedal at the bottom. If you try to compensate (for what reasons, I'm not sure) for short cranks by lifting the seat, then you won't be able to reach the pedals properly. And, for any given saddle height, bar height mostly affects how bent-over you are. What effect are you looking for it to have on your legs? – David Richerby Mar 3 '18 at 1:00
  • Longer and longer seatposts is a recipe for frame cracks and bent seat posts. Don't expect a longer seatpost will make any bike fit you. I've broken 2 frames with that mindset. – Criggie Mar 3 '18 at 2:59
  • 1
    An electric bike would tend to be sized for someone who does not really want to cycle very energetically. So the seat would tend to be lower and the cranks shorter than the "ideal" bike for some cyclist of the same size. – Daniel R Hicks Mar 3 '18 at 14:47
  • 2
    @Criggie because of weird one size fits all geometry, thick steel tubes, extremely low blobby saddle, what looks like square taper bottom bracket, huge rear derailleur lower pulley and mechanical discs are all signs of one. And I wrote that it looks like BSO, it might be a quality bike disguised as one. – ojs Mar 5 '18 at 10:36
  • 2
    The Amazon lists says 7-speed Acera, which is strictly BSO territory. A friend of mine recently bought an E-bike at €1700 including VAT and he got aluminum frame with sane geometry, XT gears and hydraulic discs for the money. – ojs Mar 5 '18 at 18:46
4

Years ago, the US Airforce commissioned the design of a 'perfect cockpit' for a new fighter, spending millions measuring and testing pilots and coming up with the right cockpit for the perfectly average pilot. Only to find there was no perfectly average pilots to fly plane. After that, they made planes with cockpits adjustable to the actual pilots that was flying the plane.

Bikes take this further - the frame is not adjustable without making it heavy and unreliable, and unlike an aircraft, frames are relatively cheap compared to the the rest of the kit. Its cheaper and gives better bikes to make different frames.

All that aid, the bike might fit you - The US Airforce never found their perfectly average pilot, maybe the manufacturer of that E-bike has found there perfectly average rider in you.

  • 1
    You know, most of bicycles have adjustable seatposts and adjustable or replaceable handlebar stems for this exact reason. – ojs Mar 3 '18 at 9:39
  • 1
    @ojs So the USAF can use them as cockpits? Awesome! – David Richerby Mar 3 '18 at 12:46
  • 1
    @ojs - I could have gone into bike fit with seat post, crank length, bar width and height, stem length and how by changing these you can get a bike to any person, but also when you change these you change the geometry and handling characteristics, and at extreme, adversely affect he bikes handling, but did not feel I was needed to make the point. – mattnz Mar 3 '18 at 20:55
  • Actually @ojs I am glad you mentioned that.. It doesn't answer the question directly but helps me focus in on what is important. – Kevin Rowe Mar 3 '18 at 23:30
3

Do some bikes have shorter cranks on them?

Yes, but not really. The standard crank lengths are 170, 172.5 and 175mm. Those are so close together (2.5mm is a tenth of an inch) that I'm pretty sure it would be about the last thing you noticed, if you jumped onto a new bike and it had different cranks to what you were used to.

From what I can see, SRAM make cranks between 165 and 177.5mm; Shimano and Campagnolo make at least 165–175mm but, basically, any bike you buy will have one of the three standard lengths.

  • Thank you,the advice on crank lengths and their impact on bike fit was exactly what I wanted to know. – Kevin Rowe Mar 3 '18 at 18:16
2

A big part of what makes the cranks seem "short" is that the bottom bracket height is very high. On one hand, you might argue it helps improve clearance but really it's a function of the design with relatively large wheels.

Because the bottom bracket is so high up, your legs can't stretch as far down as they might and so you have to raise the seat height, which then brings in a whole cluster of other problems.

Sheldon Brown actually wrote about this problem here: https://www.sheldonbrown.com/upgrade.html

Bottom-Bracket Height

Traditional bikes for road use normally had bottom brackets about 10 5/8" from the road. Everybody knew that they shouldn't pedal while leaning sharply into a high-speed corner.

When mountain bikes became the default style of bike for most buyers, people got used to 11 1/2", 12 1/2" or even higher bottom brackets. This is a good thing for serious off-road riding, giving better clearance for logs, rocks, ruts and other obstacles.

Once the marketplace had become accustomed to high bottom brackets, manufacturers became afraid to sell bikes with low ones any more. The nightmare was that some clueless rider with a good lawyer would pedal through a high-speed corner, catch a pedal, spin out and crash. In court, the shyster could point to all the other bikes on the market with high bottom brackets, and accuse the manufacturer of making an abnormal, unsafe bike.

A high bottom bracket has no real virtue for most on-road use, and actually represents a fairly serious drawback for the typical rider. A higher bottom bracket should require a higher saddle. The higher saddle precludes putting a toe down when stopping for a red light, stop sign, etc. This is a cumulatively major inconvenience for cyclists who ride in built-up areas. It generally makes starting and stopping noticeably more awkward. (See: Starting and Stopping.)

Many cyclists, unaware of this change in geometry, adjust their saddle height as they always did, with respect to their reach to the ground. This results in their saddles' being too low for efficient pedaling, which is harmful to the knees and encourages excessive standing pedaling.

1

Your main concern will be the saddle. From the image, it is a) very low by default, and b) the tube in the frame that holds the seat post ends very low. For a good fit, your saddle must be high enough so that your leg is almost fully stretched when going through the lowest point of the pedals. Your body dictates the distance between pedals and saddle.

With the frame you've shown, that means that you must use a ridiculously long seat post. And that is a problem: The longer the seat post, the longer the lever that exerts bending force at the point where the frame starts, and thus the greater the danger of breaking the seat post. This is a strong security concern in my eyes as I have indeed already managed to break a seat post.

I would not try to fit this bike for a 6-foot person.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.