Crankset length

[Dave]

Hey hey,
Question about crank length and possible change. I'm riding a 59 bleriot protovelo that I bought used with a 175mm shimano 105 cranks on it. The pedal strike I get is kind of avoidable,but still present frequently. I've tried the mks stream pedals that it came with, along with the gr-9 platform pedals. With toe clips, they strike the ground if moving the bike without my feet in them. Any hard turns are problematic if you need to pedal through.

How much difference do you think moving to 165mm sugino xd2 cranks would provide? I'm not sure of the Q factor on the shimano cranks, or how new cranks would work with my bottom bracket (not entirely sure what's in there)....so not sure if any of these questions can be answered.

[Leslie]

If it's a recent 105, it's a Hollowtech BB, which is integrated into the crank;   to switch to the Sugino, you'd need a JIS square-taper BB in its place.... 

What tire size are you running?  If you're on 32's, might want to try 38's, that might help a bit, too... it's subtle, but, sometimes that might just be enough....

But, I would think switching to a crank w/ a shorter arm wouldn't be a bad thing, in your case... can't answer about the Q-difference and influence of that on pedal strike,, but someone probably can ....

[Dave]

Went out to look and you're correct on the Hollowtech BB.  bummer.  I'm running the col de la vie 37mm tires, so not much room there.  I guess will keep my eyes open for a BB and cranks at good prices.  Anyone on list looking to clean out their garage, let me know.

[William]

The geometry is not all that hard to figure out.  A few mm of length change will change your clearance by a few mm.  A few degrees of extra lean before you scrape.  Pedal scrapes during a deep lean can be incredibly dangerous. 

In my opinion, it is much more important to have the right length for pedalling than it is to have the right length for max turning clearance.  I ride 172.5mm on all my bikes and when I ride my wife's Betty areound the block, the 165mm arms on there feel like a midget bike to me.  Alot of the fixie crowd run 165's to promote spinning, but on a geared bike, my instinct tells me that 165s would be a mistake.  Narrow width platform pedals, like the grip kings, could make more of a difference than crankarm length, if you want to experiment more affordably. 

There's a semi-famous Greg Lemond quote about pedal clearance.  He said "if you think you need to pedal through a corner, you weren't going fast enough into the turn".  That's from a purely racer perspective.   

[Jay in Tel Aviv]

A square taper BB is $20. Not a big deal.

[Garth]

165's will help .... or be bold and go with Sugino 152's !    I'm tall with big feet and switched to these after imaging what it would feel like to have the leverage of a long crank but the speed of a short one .  So .... I tried a mid foot pedal position with my Birks ... and it was Love at first ride !!  Purrfect !   I got both leverage AND speed !   I just giggle every time I ride because I'd never have believed it had I not tried it. .. and that's what I tell anyone who asks.  Theories are like pie in the sky ....  better when tasted for real :)

[Dave]

Looks like I've got some reading/learning to do in terms of bottom brackets.  "All riv's take a 100mm with the Sugino XD-2 crank" is what rivbike says on their $40 cartridge bb page.  Then looking at Phil Wood bb's on the net there are too many options....

[Michael]

FYI:

 

I ride a 55 Bleriot with Ultegra 172.5 cranks and MKS touring pedals with toe clips.

The clips drag the ground when walking the bike, but there is nary a pedal strike when cornering (non-racer style cornering).

 

 

[Michael]

Also FYI:

Lon Haldeman, who is very tall and long limbed, rode 170 cranks on his race bike according to interview in RR.

Maybe go to 170 cranks.

[Jay in Tel Aviv]

Says 110mm, like this one,
http://www.jensonusa.com/Bottom-Brackets/Shimano-UN53-Square-Taper-BB
$10

[Dave]

Thanks Jay.  Typo on my part.  110mm.  Then with Phil Wood, seems like 110 isn't an option.....108, 111, 113.  Not that I'm ready to drop that kind of cash, but just trying to understand my options.

[Leslie]

I've got a 107 on my Bomba w/ the XD2 crankset, works fine; but the 110 would be great, too.         (My Ram has a Shimano Octalink BB/crankset, so it's not directly comparable...) 

A 170 might be good to try;  but I'm still thinking 'simpler' fixes first...   can a Bleriot fit Hetres?   That'd be a little bit more height than the Col de la Vie...  maybe not enough to matter, but, maybe so...

[Dave]

bleriot can fit hetres I believe, and hope to get a pair once these col de la vie's need replacing.  May give Grip Kings a go, although I really doubt they'll be narrower than the platform pedals or the MKS streams.

[Garth]

With a Tange or Shimano Cartridge, the 107 and 110 have the same drive side length, so the 110 simply gives you 3mm more on the left.

However, with Shimano's they have a lip built into the left side cup also so if you use a driveside spacer it won't sung up all the way with the cartridge.  FWIW .

[Steve Palincsar]

On Mon, 2013-01-21 at 13:20 -0800, Dave wrote:
> bleriot can fit hetres I believe,

Joan's definitely does. Bleriot is essentially the same as Saluki, and
mine fit Hetres.

[Joe Bernard]

The best bet for mounting XD2s on a Bleriot is to contact Rivendell for BB length. Mark's email is ma...@rivbike.com. He'll know what a Bleriot runs.

 

On the topic of pedal strike, I can't remember the last time I did that. I either coast through with inside pedal up, or carve the turn with a very shallow lean. In my opinion, most turns do not need to be pedaled through, and that habit is kinda dangerous.

 

Joe Bernard

Vallejo, CA.

[Benz, Sunnyvale, CA]

Those differences are mostly inconsequential. Take for example the 108. Compared to the 110, it's narrower by 1mm per side. OK, so sometimes that can mean the difference between the crank arms clearing the chainstay, but most of the time it's really not that important to get the BB length spot on. Especially for a square taper BB/crank system, using or not using grease on the taper and torquing to spec (whose spec) can also change the installation by millimeters.

[Dave]

Thanks for all the replies!  I talked with Brian over at RBW who suggested 170mm crank arms on the bleriot for a rider my height.  

Anyone have an extra used or new sugino xd2 170mm?

Dave

[John Le Marquand]

I have a 61cm Bleriot with Hetre tyres and fenders and the tyres
definitely improved the ride.
John

[Cyclofiend Jim]

Just a few comments on pedal strike. 

As others have mentioned, it is scarey as all get out when it happens.  I would encourage you though that it's not inherently catastrophic.  The momentum you and the bike possess when moving forward is pretty significant, and it's mostly the _reaction_ to the strike that gets you in trouble.

(and those of you who have been on the list for a while have heard me mention this idea before on bike-to-bike-tire-overlap-contact and dropping-into-expansion-crack-surprises.)

If you contact the ground near the bottom of the pedal stroke, your foot and the pedal will be through the bottom of the stroke probably faster than you can react. 

If you have a strike when your foot is forward of bottom dead center, you will probably find you stop pedaling (assuming a coastable drivetrain) rather than push through and lever the rear wheel off the ground.

It is probably a good exercise have someone lean your stationary bike with the pedal at 6 o'clock, while you look from behind to see how far you can actually lean before you hit.  I have one bike - a 650B conversion - which had a reasonably low bb to start and is extremely easy to drag a pedal.  But, with most setups, you actually have to go over pretty far. 

Of course, riding fixed is a whole different animal, as you can't stop pedaling and you do have enough momentum to lever yourself off the ground with a pedal strike.  One of the nice benefits of learning to ride on a direct drive setup is that you find you can modify bike lean versus body position. I don't corner quite the same way on a fixed setup, but in general I'm able to corner just as quickly and sharply.

hope that makes sense.

- Jim / cyclofiend.com

[Dave]

Definitely all makes sense.  I think in this case, the crank arm is really just too long for my leg length and the bike.  I've never been scared with the pedal strikes because they've been at slow speeds, but it's pretty silly.  

Going to move over to the Sugino XD2 triple in 170mm and will report back on changes.