Sunday, May 12, 2019

Bike Fits Often Help, But They Aren't Cure-alls

Bike shopping while short is a challenge
If you're a shorter cyclist (<5'5"), you're probably familiar with the frustration of trying to find a bike that fits you comfortably because the reality is that pretty-much no bike shops carry bikes / frames / parts (stocked in the store) for small riders.  If you're lucky, you are able to take advantage of the ability to be fit for a bike before buying one and hopefully are also then provided with a list of frames that will work for your fit dimensions.  If you're less lucky, the fitter will pretty much just recommend the brands they carry, and if you're less lucky still - will just mention the brands they carry even if those are not the frames that would actually fit you best.

It can be pretty daunting to buy an expensive item like a bike, without a great deal of experience on how your body should feel on it, and pretty disappointing if after getting the bike and a few rides in on it, you just aren't comfortable.  Many shops have a display of saddles which probably gives you a good idea that if yours isn't comfortable, something can be done; ie buy a new one.  Swapping out saddles is conceptually simple but can turn into a seemingly endless cycle of frustration if after trying many, something still seems "wrong".  My saddle sagas have been previously enumerated herehere, and here.

Suggestions then often move to changing out the stem as a way to bring handle bars closer, in an effort to make a frame that might have been too big in the first place work better for the rider.  This can be less expensive than buying a saddle but it starts to feel annoying that various parts of the bike you already paid for need to be changed out at added expense to get it to work for you.  And I haven't even touched on crank length yet.

The low riding position on time trial bikes can lead to uncomfortable hip angles and a feeling of being stuck at the top of the pedal stroke or somehow un-fluid while pedaling.  Did you know this can be addressed by getting a new crank with shorter crank arms?  Yep, another modification at additional expense, which is an even greater disappointment if you had already been set up with a crank-based power meter as it's possibly not going to be directly transferable.  (Crank modifications are a bit of a pain as there are various parts that might be incompatible like the chain rings, or require an adapter to make work, such as the bottom bracket).

And it's not just a matter of matching rider height with frame size.  There's also differences in how people are proportioned from the hips up versus hips down.  This is why not all riders of height X are equally happy on frame size Y.




Long crank (172.5) 
on a tiny bike (48 cm).
Shorter cyclist on a small frame
I'm about 5"3" and I used to ride a size 48 Cervelo P2C on 650 wheels (a lucky find at a bike swap).  I had a couple of fit adjustments over my 5 years with it, but ultimately something always seemed off, like I needed to bring my elbows in closer.  I don't know if a shorter stem was available or would have helped, but I didn't ask because I didn't want to use 650 wheels any more.

My coach thought the new (2015) Cannondale Slice (also 48 cm) would work well for me.  I took his word for it without doing a pre-purchase bike fit or exploring other options.  But I liked what I read about it, that it was a comfortable bike (versus being super stiff) and easy to travel with (versus some super bikes that were considered more difficult to work on).  It also uses standard cockpit components that could be adjusted readily (versus some super bikes with custom / integrated / non-adjustable stems).


First few pedal strokes
on any Cannondale TT
or road bike have felt
like this to me.

Same cyclist on small frame with 700cc wheels

I was pretty disappointed to not like my first several rides on the Slice.  It felt very squirrely and like it was on stilts or something (all Cannondales I've ridden have felt "high up" like this).  It's just something to get used to, after which this bike felt quite stable over bumps and in descents.
2016 bike fit.  Power saddle, 80 mm stem, 
uncomfortable wrist angle (!!).









Pro's:

  • The Slice is far more comfortable over rough pavement than the stiffer Cervelo was. 
  • My elbows felt better located under my shoulders. 

Con:
  • The extensions are terribly uncomfortable b/c they are too straight and force my wrists to be bent down to hold them. 
  • The front of my shoulders would get tired.  I built up tolerance to it, but it didn't feel ideal. 

ReTul bike fit (A more elaborate fitting regimen, using motion capture of sensors placed on anatomical pivot points, versus my prior "eyeball and ruler" fits.) 

After 3 years I needed a new saddle and replaced my Specialized Power with the new Power Arc.  My LBS was offering a deal on ReTul bike fits and I thought this process would involve me getting on the ReTul bike and coming away with what my ideal bike setup should be, so that I could maybe find more comfort in the cockpit.  However the fitter said he found little value in doing that unless the person was shopping for a new bike, as it often turned out the customers' current bike would need several modifications to achieve that fit, which the customer didn't want to go for.
2018 bike fit.  Power Arc, 100 mm stem, bars 6
mm lower.  Wrist angle still uncomfortable.

Fit adjustments made:
  • The cleat shimming for my shorter leg was changed and wedge shims were added to raise the inside edge of both feet.
  • My 80 mm stem was changed to 100 mm.
  • Handlebars were lowered.
Opportunity lost:
  • This was mostly just a minor optimization session for my current setup.  Too bad, since I wondered what shorter cranks or different wrist angles would feel like (mods I may have considered, but definitely not without getting to test the crank setup first). 
This was better for a couple months but then I was back to inching around my saddle and changing my elbow position on the pads, trying to find the right combination to address what still felt "off".  I concluded my wrists needed to come up.  Rolling up a towel, laying it across my extensions, and resting my wrists on that immediately alleviated some of the forward pressure on my saddle and also eased tension in my shoulders and neck.  Not to mention how much more comfortable my wrists would be if my extensions came up to this new relaxed wrist angle.

By this point I'd found the TriRig Alpha 1 thread on SlowTwitch.  This TT handlebar / arm pad set allows for a large range of facile adjustability (arm pad height, width, & forearm angle) so it would be easy to tweak position over time as riders grew stronger, more flexible, or just needed more time to dial in their fits.  At this point I was ready to try modifying my fit on my own, and ordered a set.

To be continued...

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