Published by Tristan on 09 Jul 2010 at 03:34 pm
Manly cranks
After racing the Kapiti winter series last weekend I met Adrian who let me have a quick spin on his custom Zinn with 210mm cranks. With an 825mm seat height it’s not often I get on a bike which is too big for me!
The car ride home from the race was spent with discussing pros and cons with tech-heads Cameron and Stu with the general consensus that the idea makes sense in theory. But we don’t ride our bikes in theory. I’ve always ridden 175mm cranks but often wondered what longer cranks would be like and while having a natter to DB he mentioned a pair of Record 180mm cranks collecting were dust on his workbench and offered to lend them to me.
These cranks are from the early 2000′s. Campagnolo had produced their first carbon crank a few years earlier and although they’re one of the nicest looking cranks ever made they had some issues with the pedal area falling out. The next generation of carbon cranks (what I was using) were much more reliable but only offered up to 175mm and as a result Belgian hardmen like Boonen refused to use the newer carbon cranks and instead opted for aluminium cranks similar to what arrived in DB’s courier bag.
The 5mm longer cranks mean that I can lower my seat 5mm and move it forward 5mm which should get my weight towards the center of the bike more. The weight gain of aluminium cranks from carbon was 105 grams.
I’m looking forward to riding these cranks over the weekend and seeing if they have any effect on my riding. I need all the help I can get :-)
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Alan on 09 Jul 2010 at 3:48 pm #
Is that an MV agusta in the background…lucky bastard ;)
Tristan on 09 Jul 2010 at 3:51 pm #
Sure is…it’s not mine though. I just sit on it and make motorcycle sounds in my head.
Ben on 09 Jul 2010 at 9:21 pm #
Will be really interested to see what you think as I’ve had mixed experience.
Excuse the geekage..
SteveO rides 180′s on his TT and 177.5′s on his road bikes and these really suit his diesel style while I’ve only gone big on the TT bike having found a few years back that the longer cranks while better for climbing and sprinting didn’t suit me in longer rides and races. Real data showed my avg cadence was 5 to 10 rpm lower with the effect particularly noticeable after 3hrs +.
Over a 40k TT longer cranks are pure more power. The powertap says so because you (well I!) don’t suddenly pickup and equally drop FTP wattage mid season.
Max Testa once told Chris McCormack (who was using longish cranks at the time) that its like trying to spin a tennis ball on a string, the shorter the string the easier it is to keep doing it well for a long period of time. McCormack dropped to shorter cranks and immediately improved. I recall a famous texan also doing the same on Testa’s advice.
A couple of things come immediately to mind:
1) While it increases your torque slightly I figure its also adding 31 odd mm in distance traveled every revolution – potentially 500m of extra work over a 3hr ride per leg assuming you don’t two stroke it!
2) You’ve dropped your saddle height but your thighs are now coming 10mm higher at TDC, this could take some adaption initially and this may be biomechanically inefficient for you.
3) Cadence may drop simply because you maintain the same effective pedal velocity.
Any other thoughts from folks using or tried them that agree/disagree with my experience?
Tristan on 09 Jul 2010 at 9:40 pm #
Ben; nothing like a good biketech topic to get you furiously mashing at your keyboard :-D
I think a lot of the long-crank advantage suits heavier riders where they can turn higher weight and increased muscle mass into power. As a generalization larger riders have a lower cadence so the cadence drop might not be so much of an issue. With my spindly legs I’m not sure if they’ll give the same benefits.
I’m not anticipating the 10mm at TDC to be too much of an issue once I’m used to the movement. I’m reasonably flexible and there isn’t much of a beer gut to interfere.
The biomechanics are my main concern. My knees and hip flexors tend to be very sensitive to small changes in bike position so I’m anticipating a bit of discomfort while getting used to the cranks. I also think the balance between ‘getting used to’ and ‘not right for me’ will be hard to judge.
Reading other peoples tales has shown that the change tends to be either love or hate with very little middle ground.
I didn’t have a chance to get out on the bike today so the race tomorrow will be my first use of the cranks – not ideal. Hopefully I can use the warmup to get the saddle position dialed in and remove any discomfort.
Tristan on 09 Jul 2010 at 10:04 pm #
It’s also interesting that we’re talking about a mere 5mm change to cranklength. Zinn’s suggestions for my inseam are 197 > 202mm…a full 25mm more than what I’m currently using!
Tristan on 10 Jul 2010 at 2:43 pm #
I woke up with a bit of a head-cold this morning so I didn’t head up to Te Horo, but I did jump on the bike for an hour to try the new cranks. First impression: WOW! I liken it to the feeling of finding the right saddle – it just felt ‘right.’ Most noticeable was the feeling of being able to get ontop of a gear in the first few metres of a climb or undulation. Climbing out of the saddle felt great and far more natural and comfortable, in the saddle felt a little strange but still felt powerful. I climbed Korokoro in 10:20 (bus stop > bus stop) which isn’t a bad time considering I wasn’t pushing it.
I noticed the extra 10mm at TDC but it didn’t feel uncomfortable. No other biomechanical issues came out in the hour I was out but a longer ride will be the true test.
On a side note the handlebars are now 5mm higher and closer. A few weeks back I’d tried raising the bars 5mm and I didn’t like it, but funnily enough the height felt fine today. With winter shrinkage I’d recently switched from a 130mm to 120mm stem (a 125mm would have been ideal) and I’ll now switch back to the 130mm as I felt cramped on the drops and tops of the bar.
So my first impressions are positive :-)
Troy on 13 Jul 2010 at 2:08 am #
I guess my body doesn’t seem to care about small crank length changes as I tried experimenting with crank lengths last summer. I normally ride 175mm and tried 172.5, 175, 177.5 and 180′s and the only time a really felt much of difference is when I switched from 172.5 to 180.
Adrian on 18 Nov 2010 at 11:32 pm #
Missed this thread…
Feel free next time to take my Zinn for a longer ride Tristan.
I completely agree with your comment about being able to get on top of a gear quickly. It’s the thing that’s been the most beneficial to me. The accelerations that used to spit me out the back are way way more manageable.
I went from 175′s on my old bike to the 210′s on the Zinn – and it did feel weird to begin with. But that feeling quickly disappears. Now going back to my mountainbike with it’s little 175′s feels like I’m riding a kids bike!
I know people feel strongly about crank lengths – but most of the people who deride the proportional length cranks – simply aren’t my height or weight. I do know that they have made a phenomenal difference for me…
My cadence did drop for a while – but I’ve been training myself to spin more – and it’s pretty good now.
And absolutely fine over a long ride.
Cheers
Adrian.
Tristan on 19 Nov 2010 at 8:00 am #
Thanks Adrian
I’ve been riding the 180s non-stop since fitting them and I do like them! I’d like to try a longer crank at some point but I think it would need a custom frame like your Zinn with a higher BB as I definitely notice the reduction in cornering clearance – my Litespeed is pretty oldskool in this respect with a 74mm BB drop compared to many ‘crit’ frames with 68mm drop.
I don’t have a cadence sensor but I don’t think my cadence has dropped.
Thanks for your comments
Tristan