Millions of Shimano cranks worldwide need to be inspected and possibly replaced. Graduate engineer Dirk Zedler has been the most important expert on the subject of bicycle safety for years. TOUR asked him for his opinion on the crank problem.
TOUR: Have you checked affected cranks yourself?
ZedlerYes, we simply asked the employees to bring their bikes in and then carried out the Shimano test routine. It is important to look at the identification of both crank arms because they may be different production batches. And then we carried out the rest of the test routine on the potentially affected bikes: that means dismantling the cranks, unscrewing the chainrings and cleaning them completely - Shimano has very detailed inspection instructions for this. It looks cryptic on paper, but in practice it wasn't difficult. Our cranks were all in order.
67 euros for specialised dealers
TOUR: The dealers get 67 euros for the inspection and Shimano estimates 45 minutes of working time. Is that realistic?
ZedlerIt depends on how the bike looks. If the crank is clean, then it can be done relatively quickly. I don't think this is an issue for a dealer who has a lot of racing bikes. The difficulties start with mail order bikes that don't have a proper dealer structure behind them. Canyon probably sold several hundred thousand road bikes between 2012 and 2019 and the likelihood of Canyon having Dura Ace or Ultegra on them is relatively high. I can already see the difficulty of how this should be handled.
TOUR: Can you really recognise damage?
ZedlerYou can see very clearly that an intact crank looks very different from what you see in the Shimano pictures. We're talking about small cracks, small gaps in the bonding zone, etc. and the comparison was not an issue for my team. An experienced bike dealer can do this in bright light and with a magnifying glass. The pictures from Shimano in the user manual also show a real crack pattern on the outside, i.e. if the two halves are loose or start to come loose, then movement starts and this movement then leads to cracks that you can recognise on the outside over time. Shimano says: Look inside where you don't normally look.
TOUR: But what if the cracks are so small that you can't recognise them yet?
Zedler: This is precisely the difficulty of the matter: you actually have to check the crank again at regular intervals from now on. Every fatigue fracture, every failure is typically also a function of use over time. If we have checked it today, then it basically means nothing - I have to do it every now and then. That's a bit of a weakness in this recall. Crack growth can occur at some point. You do the check and the bike has 1000 kilometres, but then it changes hands and a frequent rider rides 10,000 kilometres the next year - then the crank can look completely different. This means you have to check the crank regularly - a one-off check is definitely not enough. In my opinion, it has not yet been clearly communicated that these cranks need to be checked at least once a year if I am a regular cyclist. But if I'm an amateur cyclist, I actually have to inspect the cranks every three months to be able to ride safely and with a clear conscience.
Shimano cranks recall: these are warning signals
TOUR: What can you do yourself to recognise damage?
ZedlerI've been saying this for many years: Don't just clean your bike with a water hose, but also go over it with a clean cloth and wipe everything dry by hand. Because when you clean by hand, you notice when cracks start to appear. Shimano carries out a purely visual check - in the end, anyone can do this for their own safety. In my opinion, it's unrealistic to go to the dealer every three or four months and say I'm going to have a bike disassembled and the cranks checked. In practice, road cyclists rarely go for inspections.
TOUR: What are absolute warning signals? Noises?
ZedlerYes! Shimano also explicitly points out that noise can occur when the cracks appear. And if cracks are visible during the inspection, the bike simply has to be paralysed.
TOUR: How do you categorise the recall of the Shimano cranks overall?
ZedlerThe number of units sounds enormous. But I generally consider Shimano to be a very reputable manufacturer. I have been involved in many material litigation cases in recent years - both in court and in the private sector. There have been many manufacturers who should have recalled much more urgently than Shimano. I think Shimano is already on the right track, of course also thanks to the American market.
TOUR: A class action lawsuit is already being prepared in the USA ...
ZedlerYes, in America there is a completely different legal system and lawyers are often paid according to their success and seek out such cases against large producers. But according to the information we now have six injured people in America. That sounds like a lot, but I also know bicycle component or bicycle manufacturers who produce much smaller quantities and have not recalled them, even though they also had relevant difficulties. We had seat posts with a central bolt for years and there were thousands of broken bolts with many serious crashes. Virtually nobody recalled these screw-in seatposts and they were never banned. I don't want to minimise the problem, but I know many companies that would also have many reasons to recall them.
Background info Shimano cranks recall:
There have been reports of problems with eleven-speed Shimano road bike cranks for years. In the affected Hollowtech cranks, the glued parts of the crank arm can become detached and break. In response, Shimano is launching an "inspection and replacement programme". The cranks affected are Ultegra FC-6800, Dura-Ace FC-9000, Ultegra FC-R8000, Dura-Ace FC-R9100, Dura-Ace FC-R9100P with certain serial numbers from 2012 to 2019. You can check the production number yourself - the other work will be carried out by your specialist dealer. If the crank shows cracks, it must be sent to Shimano. The replacement cranks are from the twelve-speed series with an eleven-speed chainring. This means a different colour and a different chainring attachment. If you had cross chainrings or chainrings on your time trial bike, you can no longer use them on the new cranks.
The two-digit manufacturing code must match the following abbreviations. This can also be found on the inside of the crank arm in the last line of the model designation next to the information for the crank length. The affected models were manufactured before July 2019
- KF, KG, KH, KI, KJ, KK, KL
- LA, LB, LC, LD, LE, LF, LG, LH, LI, LJ, LK, LL
- MA, MB, MC, MD, ME, MF, MG, MH, MI, MJ, MK, ML
- NA, NB, NC, ND, NE, NF, NG, NH, NI, NJ, NK, NL
- OA, OB, OC, OD, OE, OF, OG, OH, OI, OJ, OK, OL
- PA, PB, PC, PD, PE, PF, PG, PH, PI, PJ, PK, PL
- QA, QB, QC, QD, QE, QF, QG, QH, QI, QJ, QK, QL
- RA, RB, RC, RD, RE, RF
More Info to the Shimano cranks recall
Kristian Bauer
Editor
